Evaluation of 2009 

Pandemic Influenza A 

(H1N1) Virus Exposure 

Among Internal Medicine 

Housestaff and Fellows

Marie A. de Perio, MD

Scott E. Brueck, MS, CIH

Charles A. Mueller, MS

Health Hazard Evaluation Report

HETA 2009-0206-3117

University of Utah School of Medicine

Salt Lake City, Utah

October 2010

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

Workplace

Safety and Health

 National Institute for Occupational 

Safety and Health

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific 

facility evaluated and may not be universally applicable. Any recommendations made are not to be 

considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE 

reports are available at http://www.cdc.gov/niosh/hhe/
The employer shall post a copy of this report 

for a period of 30 calendar days at or near 

the workplace(s) of affected employees. The 

employer shall take steps to insure that the 

posted determinations are not altered, defaced, 

or covered by other material during such 

period. [37 FR 23640, November 7, 1972, as 

amended at 45 FR 2653, January 14, 1980].
Health Hazard Evaluation Report 2009-0206-3117 Page i

Report Abbreviations.......................................................................ii

Highlights of the NIOSH Health Hazard Evaluation............ iii

Summary .............................................................................v

Introduction..........................................................................1

Assessment.........................................................................4

Results.................................................................................8

Discussion .........................................................................20

Conclusions.......................................................................23

Recommendations.............................................................24

References ........................................................................27

Contents

Ac Acknowledgments and Availability of Report.....................31 knowledgments
Page ii Health Hazard Evaluation Report 2009-0206-3117

CDC Centers for Disease Control and Prevention

CFR Code of Federal Regulations

CI Confidence interval

DFA Direct immunofluorescence assay

GEWDVAMC George E. Wahlen Department of Veterans Affairs Medical Center

HCH Huntsman Cancer Hospital

HCP Healthcare personnel

HHE Health hazard evaluation

ICU Intensive care unit

ILI Influenza-like illness

IMC Intermountain Medical Center

NAICS North American Industry Classification System

NIOSH National Institute for Occupational Safety and Health

OR Odds ratio

OSHA Occupational Safety and Health Administration

PAPR Powered air-purifying respirator

PCMC Primary Children’s Medical Center

pH1N1 2009 pandemic influenza A (H1N1)

PPE Personal protective equipment

RT-PCR Reverse transcriptase polymerase chain reaction

UH University Hospital

UUSM University of Utah School of Medicine`

Abbreviations
Health Hazard Evaluation Report 2009-0206-3117 Page iii

What NIOSH Did

● We visited UUSM and the four associated medical centers 

in September 2009. We met with housestaff, fellows, and 

staff members at each center to learn more about their 

experiences during the first phase of the pH1N1 pandemic.

● We estimated the prevalence of pH1N1 infection and 

influenza-like illness (ILI) and identified modes of 

transmission among internal medicine housestaff, cardiology 

fellows, and pulmonary and critical care fellows.

● We assessed their knowledge, attitudes, and practices towards 

influenza infection control measures.

What NIOSH Found

● We found that most of the 88 responding physicians 

reported exposure to patients and/or coworkers with pH1N1 

or ILI at work and/or outside of work.

● Thirteen cases of ILI, with five laboratory-confirmed 

diagnoses of influenza A, occurred in responding physicians 

in May–June, 2009. Transmission likely occurred at work and 

outside of work.

● We found gaps in infection control knowledge and 

in adherence to personal protective equipment (PPE) 

recommendations. We also found incomplete exclusion of ill 

housestaff and fellows from work.

● The medical centers reported running out of supplies of 

N95 respirators and having difficulty obtaining additional 

supplies.

● Some housestaff and fellows had not been fit tested for N95 

respirators.

What the Program and Medical Center 

Managers Can Do

● Develop procedures for tracking ill housestaff and fellows 

and excluding them from work.

● Develop a written plan for staffing of housestaff and fellows 

in the event of a pandemic or other emergency.

The National Institute 

for Occupational Safety 

and Health (NIOSH) 

received a request for a 

health hazard evaluation 

(HHE) at the University of 

Utah School of Medicine 

(UUSM) in Salt Lake 

City, Utah. The internal 

medicine residency 

director submitted the 

HHE request because 

of concerns about the 

exposure of internal 

medicine housestaff to the 

2009 pandemic influenza 

A(H1N1) (pH1N1) virus.

Highlights of the

NIOSH Health

Hazard Evaluation
Page iv Health Hazard Evaluation Report 2009-0206-3117

Highlights of the

NIOSH Health

Hazard Evalution

(continued)

● Educate housestaff and fellows on the evaluation, diagnosis, 

treatment, and complications of patients with symptoms 

of influenza. Recommended isolation precautions, proper 

hand hygiene, and use of recommended PPE should also be 

covered.

● Continue to require housestaff and fellows to get the annual 

seasonal influenza vaccine as part of a comprehensive 

influenza infection control strategy.

● Place signs indicating appropriate isolation precautions 

outside patients’ rooms as soon as patients are placed in the 

rooms.

● Limit healthcare personnel entering the room of a patient 

in isolation precautions for influenza to those performing 

patient care activities.

● Develop, implement, and maintain a respiratory protection 

program for all housestaff and fellows to protect against 

airborne infectious agents.

● Work with a designated person in charge to ensure an 

adequate inventory of N95 respirators for emergencies.

What Housestaff and Fellows Can Do

● Self assess for symptoms of ILI. Report any symptoms to 

appropriate supervisors as soon as possible.

● Do not report for work when ill.

● Get the seasonal influenza vaccine every year.

● Use recommended PPE when caring for critically ill and 

noncritically ill pH1N1 and ILI patients.
Health Hazard Evaluation Report 2009-0206-3117 Page v

In August 2009, NIOSH received an HHE request from the 

director of the internal medicine residency program at UUSM 

concerning the exposure of internal medicine housestaff to the 

pH1N1 virus. A number of internal medicine housestaff were 

reportedly diagnosed with pH1N1 in June 2009, and more 

housestaff were reported to have ILI, leading to significant 

absenteeism in this program. The exact extent of the disease, risk 

factors leading to infection, and modes of transmission among 

the internal medicine housestaff were unknown at the time of the 

request.

In August–September 2009, we performed a cross-sectional study 

to examine pH1N1 exposure; determine the prevalence of pH1N1 

infection and ILI; identify modes of transmission; and identify 

risk factors for infection among the internal medicine housestaff, 

cardiology fellows, and pulmonary and critical care fellows who 

were in the program at any time from May 1–June 30, 2009. We 

also assessed knowledge, attitudes, and practices towards influenza 

infection control measures. We made a site visit to UUSM and the 

four associated medical centers in September 2009, to meet with 

housestaff, fellows, and staff members at each of the four medical 

centers to learn about their experience during the early 2009 

pH1N1 pandemic.

We found that most of the 88 responding physicians reported 

exposure to individuals with pH1N1 or ILI either at work or 

outside of work. Most respondents reported having contact with 

a patient with confirmed or probable pH1N1 or ILI but also 

reported contact with ill coworkers at work and outside of work. 

Thirteen cases of ILI, with five laboratory-confirmed diagnoses of 

influenza A, occurred in responding physicians in May–June 2009. 

Transmission likely occurred at work and outside of work.

We concluded that all four medical centers were appropriately 

using the occupational health hierarchy of controls approach to 

prevent influenza transmission within their centers and to prevent 

exposure of healthcare personnel. Comprehensive programs were 

in place, and innovative methods of infection control had been 

implemented with respect to engineering and administrative 

controls. However, our survey results show some gaps in infection 

control knowledge, incomplete exclusion of ill housestaff and 

fellows from work, and gaps in adherence to PPE use.

We recommend that the residency and fellowship programs have 

procedures for tracking ill and absent housestaff and fellows. The 

NIOSH investigators 

evaluated internal 

medicine housestaff 

and fellow exposure 

to pH1N1 virus at four 

medical centers in Utah. 

We identified 13 cases 

of influenza-like illness, 

likely acquired at work or 

outside of work, among 

this group. Lapses in 

administrative controls 

and PPE use for influenza 

exposure were also 

identified.

Summary
Page vi Health Hazard Evaluation Report 2009-0206-3117

Summary (continued) programs should also develop a written plan for staffing in the 

event of a pandemic or other emergency. Housestaff and fellows 

should be encouraged to self assess for symptoms. Housestaff 

and fellows with febrile respiratory illness should be excluded 

from work according to the most recent CDC guidance, found 

at http://www.cdc.gov/flu/professionals/infectioncontrol/

healthcaresettings.htm. They should also be encouraged to avoid 

social events outside of work.

Education and training of housestaff and fellows should be 

provided at least annually regarding the evaluation, diagnosis, 

treatment, and complications of patients with symptoms of 

influenza; the recommended isolation precautions at each of 

the four medical centers; proper hand hygiene; and the proper 

donning, use, and removal of recommended PPE. Housestaff, 

fellows, and all medical center employees should continue to be 

required to receive the annual seasonal influenza vaccine as part 

of the comprehensive influenza infection control strategy. The 

vaccine should be made available to all housestaff and fellows at 

their assigned medical centers. Signage indicating appropriate 

isolation precautions should be placed outside of patients’ rooms 

concurrent with placement of patients in rooms. HCP entering the 

room of a patient in isolation precautions for influenza should be 

limited to those performing patient care activities.

A respiratory protection program should be developed, 

implemented, and maintained for all housestaff and fellows 

to protect against airborne infectious agents. All housestaff 

and fellows should receive training, receive medical clearance, 

and undergo fit testing as specified in the OSHA Respiratory 

Protection Standard (29 CFR 1910.134). PPE, including gloves, 

gowns, surgical masks, N95 filtering facepiece respirators, and eye 

protection, should be made readily available near patient rooms 

according to hospital guidelines. PPE use should be emphasized 

when caring for critically ill and noncritically ill pH1N1 and ILI 

patients. The medical centers should ensure appropriate stockpiles 

of N95 respirators and other PPE in preparation for potential 

outbreaks of airborne infectious agents.

Keywords: NAICS 622110 (General Medical and Surgical 

Hospitals), pandemic, H1N1, influenza, hospital, physicians, 

influenza-like illness, personal protective equipment
Health Hazard Evaluation Report 2009-0206-3117 Page 1

Introduction

On August 3, 2009, NIOSH received an HHE request from 

the internal medicine residency program director at UUSM 

concerning the exposure of internal medicine housestaff to 

pH1N1 virus. Several internal medicine housestaff were reportedly 

diagnosed with pH1N1 in June 2009, and more housestaff were 

reported to have ILI, leading to significant absenteeism. The exact 

extent of the disease, risk factors leading to infection, and modes 

of transmission among these residents were unknown.

University of Utah School of Medicine 

The Internal Medicine Residency program at UUSM consisted of 

120 residents or housestaff in three programs: a 3-year categorical 

internal medicine program, a 4-year medicine-pediatrics program, 

and a 1-year preliminary program for residents planning to enter 

noninternal medicine disciplines. Housestaff rotate biweekly 

or monthly through a variety of inpatient, critical care, and 

ambulatory training experiences at four acute care hospitals: UH/

HCH, GEWDVAMC, IMC, and PCMC.

The UUSM Division of Cardiology offers subspecialty fellowships 

in cardiovascular disease (3 years), clinical cardiac electrophysiology 

(2 years), interventional cardiology (1 year), and heart failure/

transplant (1 year). The UUSM Division of Pulmonary and 

Critical Care Medicine provides a 3-year fellowship in pulmonary 

and critical care medicine. Cardiology and pulmonary and critical 

care fellows rotate at UH, GEWDVAMC, and IMC during their 

clinical training.

University Hospitals & Clinics is a healthcare system that consists 

of UH/HCH, University Orthopaedic Center, the University 

Neuropsychiatric Institute, 10 community clinics, and several 

specialty centers. UH/HCH, located in Salt Lake City, Utah, 

serves as an academic tertiary care center for the area and has 

500 inpatient beds. GEWDVAMC, also located in Salt Lake 

City, Utah, is a midsized tertiary care facility with 121 inpatient 

beds. IMC, a tertiary care center located in Murray, Utah, has 

450 inpatient beds. PCMC, an academic tertiary care center for 

children located in Salt Lake City, Utah, has 271 inpatient beds. 

All four medical centers serve as referral centers for patients from 

Utah, Idaho, Wyoming, Nevada, and Montana.
Page 2 Health Hazard Evaluation Report 2009-0206-3117

Introduction 

(continued) 2009 Pandemic Influenza A (H1N1) Virus 

The pH1N1 virus, also referred to as “swine flu,” was first detected 

in humans in the United States in April 2009. On June 11, 

2009, the World Health Organization signaled that a pandemic 

of pH1N1 was underway. During the spring of 2009, more than 

40,000 confirmed or probable cases and more than 300 deaths in 

the United States were reported to CDC [CDC 2009a].

Spread of the pH1N1 virus is similar to that of seasonal influenza 

[CDC 2009b]. Influenza viruses are spread mainly through droplet 

transmission though evidence for airborne transmission and 

transmission via direct contact also exists [CDC 2009b].

The symptoms of pH1N1 infection include fever, cough, sore 

throat, runny or stuffy nose, body aches, headache, chills, and 

fatigue. Some patients have vomiting and diarrhea, while others 

have respiratory symptoms without a fever. Illness with the pH1N1 

virus has ranged from mild to severe. While most ill people have 

recovered without medical treatment, hospitalizations and deaths 

from pH1N1 infection have occurred. Many patients with illness 

resulting in hospitalization or death had one or more medical 

conditions previously recognized as placing people at “high risk” 

of serious seasonal influenza-related complications, including 

pregnancy, diabetes, heart disease, asthma, and kidney disease 

[CDC 2009b].

In the state of Utah, 210 hospitalized cases of confirmed pH1N1 

infection and 10 deaths were reported as of June 24, 2009 [UDOH 

2009c]. Utah was one of 11 states considered to have widespread 

influenza activity at the time. ILI illness rates were also reported to 

have been elevated above the expected level in June 2009 [UDOH 

2009c].

In the United States, more than 13 million people are employed in 

healthcare settings, representing 9% of the entire U.S. workforce 

[The New York Center for Health Workforce Studies 2006]. 

Seasonal influenza has been shown to spread rapidly among 

patients and HCP in healthcare settings with attack rates among 

HCP from 11%–59% [Van-Voris et al. 1982; Evans et al. 1997; 

Cunney et al. 2000; Malavaud et al. 2001; Salgado et al. 2002; 

Horcajada et al. 2003]. HCP are among the occupational groups 

considered at highest risk for exposure to pandemic influenza virus 

[OSHA 2009].
Health Hazard Evaluation Report 2009-0206-3117 Page 3

Introduction (continued) Early in the pandemic in April–May 2009, CDC reported details 

on 26 case reports of novel influenza A (H1N1) infection in HCP 

that were defined as confirmed or probable [CDC 2009j]. Of the 

26 cases, 13 (50%) HCP had acquired infection in a healthcare 

setting, including one instance defined as probable HCP to HCP 

transmission and 12 instances defined as probable (5) or possible 

(7) patient to HCP transmission. Eleven HCP were defined to have 

probable (10) or possible (1) transmission in the community, and 

two had no reported exposures in either healthcare or community 

settings. Among 11 HCP with probable or possible patient to 

HCP acquisition and available information on PPE use, only three 

reported always using either a surgical mask or an N95 filtering 

facepiece respirator. These findings suggested that transmission 

of pH1N1 virus to HCP was occurring in both healthcare and 

community settings [CDC 2009j].

Strategies for prevention and control of seasonal influenza in acute 

care facilities have traditionally included (1) annual influenza 

vaccination of all eligible patients and HCP, (2) implementation 

of standard and droplet precautions for infected individuals, (3) 

active surveillance and influenza testing for new illness cases, (4) 

restriction of ill visitors and personnel, (5) rapid administration 

of influenza antiviral medications for treatment and prevention 

during outbreaks, and (6) education about respiratory hygiene/

cough etiquette. CDC made interim recommendations for the use 

of Standard and Contact Precautions [Siegel et al. 2007] plus eye 

protection and a fit-tested disposable N95 respirator by HCP when 

caring for patients with confirmed, probable, or suspected pH1N1 

infection [CDC 2009i] early in the pandemic because of concerns 

about potential transmission of pH1N1 infections to HCP and 

uncertainty about virulence.

Initially, all four associated medical centers followed CDC interim 

guidance for PPE use by HCP when caring for pH1N1 patients 

[CDC 2009i]. However, because of logistical issues detailed later 

in this report, three medical centers deviated from this guidance 

beginning in June 2009. Minimum PPE recommendations 

for infection control when caring for patients with confirmed, 

probable, or suspected pH1N1 or ILI patients by medical center, 

as of September 2009, are shown in Table 1. All centers required 

the use of gloves, gown, either a fit-tested N95 filtering-facepiece 

respirator or PAPR, and eye protection during presence at any 

aerosol-generating procedures.
Page 4 Health Hazard Evaluation Report 2009-0206-3117

Introduction 

(continued)

Our evaluation had two components: (1) a cross-sectional survey 

to examine pH1N1 exposure among internal medicine housestaff 

and fellows and (2) a site visit to UUSM and the four associated 

medical centers to meet with housestaff, fellows, and staff and 

learn about each medical center’s experience during the early 

pH1N1 pandemic.

Cross-Sectional Study 

We performed a cross-sectional study to examine pH1N1 exposure 

among internal medicine housestaff, cardiology fellows, and 

pulmonary and critical care fellows who were in the program at any 

time from May 1–June 30, 2009. Our objectives were to determine 

the prevalence of pH1N1 infection and ILI, identify modes of 

transmission, and identify risk factors for infection. We also 

sought to assess knowledge, attitudes, and practices towards use of 

hospital-recommended PPE and other influenza infection control 

measures.

We e-mailed an electronic questionnaire to the current and recently 

graduated housestaff and fellows and extracted information 

from multiple sources including: (1) residency program records 

regarding rotation schedules, (2) medical records of ill housestaff 

and fellows, and (3) medical records of confirmed and probable 

pH1N1 patients hospitalized at the four associated medical centers. 

We also reviewed the medical centers’ infection control and PPE 

policies and procedures.

Assessment

Table 1. Minimum personal protective equipment recommendations for infection control when caring for 

influenza patients (excluding aerosol-generating procedures) by medical center as of September 2009

PPE Component UH/HCH GEWDVAMC IMC PCMC

Gloves Yes Yes Yes Yes

Gown No Yes No Yes

Surgical mask Yes No Yes Yes

Fit-tested N95 respirator No Yes No No

Powered air purifying respirator No Yes No No

Eye protection Yes Yes No Yes
Health Hazard Evaluation Report 2009-0206-3117 Page 5

Assessment (continued) Electronic Questionnaire

In August and September 2009, we e-mailed an electronic 

questionnaire to 210 current and recently graduated internal 

medicine housestaff, cardiology fellows, pulmonary fellows, and 

critical care fellows. Because the period of interest was 

May 1–June 30, 2009, any internal medicine resident or cardiology 

or pulmonary and critical care fellow in the program at any time 

during this period was invited to participate. The questionnaire 

included questions regarding personal characteristics, work history, 

history of exposure to pH1N1, and ILI symptoms.

A confirmed case of pH1N1 infection was defined as a person with 

ILI and laboratory-confirmed pH1N1 virus infection by real-time 

RT-PCR and/or viral culture. A probable case of pH1N1 infection 

was defined as a person with ILI who was positive for influenza 

A, but negative for human H1 and H3 by influenza RT-PCR. In 

the questionnaire, ILI regarding individuals to whom respondents 

were exposed was defined as fever (temperature of 100°F or greater) 

and a cough and/or a sore throat in the absence of a known cause 

other than influenza. We classified responding physicians as having 

ILI if they reported being sick with fever and either sore throat or 

cough. This latter definition is consistent with the case definition 

used in other CDC pH1N1 investigations [CDC 2009i, 2010b].

Knowledge and attitudes regarding use of PPE and adherence to 

other influenza infection control measures were also examined. 

We used some questions adapted from a previously published 

paper regarding PPE use for control of influenza among critical 

care clinicians [Daugherty et al. 2009] that applied the Theory of 

Planned Behavior, a widely accepted approach in predicting social 

and health behavior, and also developed new questions applying 

this approach [Ajzen 1991]. A central factor in the Theory of 

Planned Behavior is the individual’s intention to perform a given 

behavior. Intention is predicted directly by three intermediate 

variables: attitude (feelings towards the behavior), subjective norm 

(a person’s perception of the social pressure to perform or not 

perform the behavior), and perceived behavior control (a person’s 

perception of the ease or difficulty in performing a target behavior) 

[Ajzen 1991]. Some PPE knowledge and attitudes questions were 

examined by degree of agreement with statements about influenza 

infection control, using a five-point Likert scale (i.e., disagree, tend 

to disagree, neither agree nor disagree, tend to agree, and agree). 

Respondents were also given a list from which to choose PPE that 
Page 6 Health Hazard Evaluation Report 2009-0206-3117

Assessment (continued) were included in infection control precautions when caring for the 

patients being evaluated for pH1N1 at each medical center.

Practices regarding use of PPE and adherence to other influenza 

infection control measures, including previous seasonal influenza 

vaccination, hand hygiene, respirator training, and respirator fit 

testing, were also examined. Respondents were asked to report the 

proportion of time (never, some of the time, most of the time, and 

always) they used PPE when in close contact with patients with 

confirmed or probable pH1N1 or ILI at each medical center.

Record Review

We reviewed residency and fellowship program records to extract 

information on year of training, rotation location and type, and 

absenteeism. We also obtained and reviewed results of laboratory 

tests from the medical records of housestaff and fellows reporting 

ILI. With the assistance of the infection preventionists from the 

associated medical centers, we reviewed the medical records of 

confirmed and probable pH1N1 patients hospitalized during the 

period May 1–June 30, 2009. We determined housestaff and fellow 

exposure to infected patients based on authorship of admission, 

progress and discharge notes, and signatures of physician orders.

Data Analysis 

We summarized survey results using medians and proportions as 

appropriate. Likert scale responses were categorized as “expressed 

agreement” if they marked “agree” or “tend to agree,” and as 

“expressed disagreement” if they marked “disagree” or “tend to 

disagree.” Characteristics and survey responses of respondents who 

reported ILI were compared to those of respondents not reporting 

ILI. Characteristics and survey responses of respondents who 

reported ILI and had a diagnosis of influenza A were compared to 

those of respondents not reporting ILI.

We categorized respondents as knowing or not knowing the 

infection control precautions related to PPE when caring for a 

patient being evaluated for pH1N1 infection at each medical 

center. Those respondents who indicated a higher level of 

respiratory protection than the minimum recommendation 

in Table 1 were also classified as knowing the respiratory 

recommendations. We decided that we could not discern whether 
Health Hazard Evaluation Report 2009-0206-3117 Page 7

Assessment (continued) the selection of full-facepiece PAPR demonstrated the knowledge 

of an eye protection recommendation. We only categorized 

respondents who had rotated at that center at any time during 

May 1–June 30, 2009, or who reported close contact (defined as 

<6 feet) with a patient with confirmed or probable pH1N1 or ILI.

For respondents who reported close contact with a confirmed 

or probable pH1N1 or ILI patient and provided responses to 

questions on use of PPE components for infection control, 

we categorized respondents into high and low PPE adherence 

groups to determine rates of adherence to the minimum PPE 

recommendations shown in Table 1.

We included respondents reporting presence at aerosol-generating 

procedures and those reporting not being present at the procedures 

with respect to adherence to the minimum PPE recommendations 

in Table 1. Although the potential for aerosol generation during 

certain procedures is still unknown, in the questionnaire we 

considered intubation, suctioning, administration of nebulizing 

medications, bronchoscopy, acquisition of a nasopharyngeal 

sample, and ventilation with bilevel positive airway pressure or 

continuous positive airway pressure to be aerosol-generating 

procedures.

Respondents indicating “never” or “some of the time” for use 

of any of the required PPE components were classified into the 

low PPE adherence group. Respondents indicating “most of the 

time” or “always” for use of all the required PPE components were 

classified into the high PPE adherence group. Those respondents 

who indicated wearing a higher level of protection than was 

recommended (e.g., an N95 respirator when only a surgical mask 

was required or a gown when it was not required) were classified 

into the high PPE adherence group as long as the required PPE 

components were also used. We reasoned that respondents using a 

level of protection beyond minimum PPE recommendations would 

be adequately protected. Respondents who indicated wearing 

a PAPR were also classified as wearing eye protection because 

the medical centers provided full-facepiece PAPRs. We then 

determined factors associated with high and low PPE adherence.

Bivariate analyses were conducted using the student’s t-test,

Pearson’s chi-square test, and Fisher’s exact test using SAS 9.2 (SAS 

Institute, Cary, North Carolina). All tests were two-tailed, and 

statistical significance was set at p<0.05. We calculated odds ratios 

and 95% confidence intervals.
Page 8 Health Hazard Evaluation Report 2009-0206-3117

Assessment (continued) Site Visit 

Meetings with Housestaff and Fellows 

We visited UUSM and the four associated medical centers on 

September 14–17, 2009. During our site visit, we attended noon 

conferences for the housestaff, cardiology fellows, and pulmonary 

and critical care fellows assigned to three of the affiliated hospitals: 

UH/HCH, GEWDVAMC, and IMC. During these conferences, 

we discussed the HHE request and the objectives and methods of 

our investigation. We answered questions from the housestaff and 

fellows and discussed their experiences and concerns regarding 

pH1N1.

Meetings with Medical Center Staff 

During our visit, we also held meetings with staff at each associated 

medical center. These meetings were attended by representatives 

from graduate medical education, infection control and hospital 

epidemiology, employee health, nursing administration, hospital 

administration, safety and environmental health, and emergency 

management. We used these meetings as a forum to learn 

about each medical center’s experience during the early pH1N1 

pandemic and discuss their implementation of infection control 

guidance.

Cross-Sectional Study 

Of 210 current and recently graduated housestaff and fellows, 88 

(42%) completed the electronic questionnaire. The median age of 

respondents was 30 years (range: 25–53 years). Other demographic 

characteristics of survey respondents are shown in Table 2. The 

respondents consisted of 75 internal medicine housestaff, 7 

cardiology fellows, and 6 pulmonary and critical care fellows. Work 

characteristics, including rotation locations and types during the 

period May 1–June 30, 2009, are shown in Table 3.

Results
Health Hazard Evaluation Report 2009-0206-3117 Page 9

Results (continued)

Table 2. Demographic characteristics of survey respondents

Demographic Characteristic No. Respondents (%)

n = 84–88*

Median age, years 30

Male sex 57 (65)

Race

 Asian 7 (8)

 Black or African American 2 (2)

 White 77 (88)

 Other 2 (2)

Hispanic or Latino ethnicity 3 (4)

Household included: 

 One or more adults ≥ 18 years old (excluding respondent) 71 (81)

 One or more child/ren ≤ 5 years old 23 (26)

 One or more child/ren between 5–18 years old 9 (10)

* Sample sizes varied due to missing values.

Table 3. Work history characteristics of survey respondents 

Work Characteristic No. Respondents (%)

n = 85–88*

Training program

 Internal medicine residency

 Categorical medicine residency 49 (56)

 Preliminary medicine residency 19 (22)

 Medicine-pediatrics residency 7 (8)

 Cardiology fellowship 7 (8)

 Pulmonary and critical care fellowship 6 (7)

Rotation location during study period†

 UH/HCH 51 (59)

 GEWDVAMC 51 (59)

 IMC 29 (34)

 PCMC 5 (6)

Rotation type during study period*

 ICU 31 (36)

 Inpatient wards 39 (46)

 Ambulatory care 36 (42)

 Night float 8 (9)

 Emergency medicine 8 (9)

 Consult service 21 (25)

* Sample sizes varied due to missing values.

† Housestaff and fellows had more than one rotation location and type during the study period.
Page 10 Health Hazard Evaluation Report 2009-0206-3117

Results (continued) According to infection control records at each medical center, 35 

patients at UU/HCH, 4 patients at GEWDVAMC, 39 patients at 

IMC, and 95 patients at PMC with confirmed pH1N1 infection 

were seen May 1–June 30, 2009. UU/HCH and GEWDVAMC 

did not have total numbers of patients with probable pH1N1 

infection, but IMC reported 19 probable cases, and PMC reported 

4 probable cases for this period. Between May 1–June 30, 2009, 

56 (65%) of 86 respondents reported having close contact with a 

patient with confirmed or probable pH1N1 or ILI while working. 

Forty-five (52%) of 87 respondents reported having close contact 

with a coworker with confirmed or probable pH1N1 or ILI at 

work, while 28 (32%) of 88 respondents reported having close 

contact with a coworker with confirmed or probable pH1N1 or 

ILI outside of work. Twelve (14%) of 88 respondents reported 

having close contact with someone in their household or in the 

community outside of the hospital with confirmed or probable 

pH1N1 or ILI. Thirteen (15%) of 88 respondents reported no 

close contact with any of the above possible sources of exposure.

Between May 1–June 30, 2009, 13 (15%) of the 88 respondents 

reported symptoms of ILI. Seven (54%) of the 13 reported seeking 

medical care from a healthcare provider for their illness. Upon 

medical record review, five (71%) of the seven had a laboratoryconfirmed diagnosis of influenza A by either viral culture or DFA. 

These five laboratory specimens did not undergo further sub-typing 

by RT-PCR, appropriately following the guidance of the Utah 

Department of Health and the Utah Public Health Laboratories 

[UDOH 2009d]. None of the seven who sought medical care were 

hospitalized.

The earliest date of symptom onset for ILI was May 10, 2009, 

reported by one respondent. Another respondent reported 

ILI symptoms starting May 30, 2009, and was diagnosed with 

influenza A by DFA on June 2, 2009. The next date of onset of 

ILI was not until June 13, 2009. The epidemic curve illustrating 

the number of cases of ILI and influenza A infection among 

respondents for June 2009 is shown in Figure 1. A cluster of 8 

cases of ILI occurred in the 48–96-hour period after the resident 

dinner. Six of these 8 individuals reported attending the resident 

dinner. While it is unknown how many total housestaff and fellows 

attended the resident dinner, 32 (37%) of 86 survey respondents 

reported attending the dinner.
Health Hazard Evaluation Report 2009-0206-3117 Page 11

Results (continued)

Figure 1. Graph illustrating the number of cases of ILI and influenza A infection among 

respondents by date of symptoms onset in June 2009.

Respondents with ILI were asked if they had close contact with 

anyone with confirmed or probable pH1N1 or ILI in the 7 days 

before symptom onset. Of the 13 respondents with ILI, two 

reported no known exposure. Two reported only having known 

close contact with one or more confirmed or probable pH1N1 or 

ILI patients, and two reported only having known close contact 

with coworkers with confirmed or probable pH1N1 or ILI at work, 

making healthcare-associated acquisition of infection likely for 

these four respondents. One respondent with ILI reported only 

having contact with coworkers with confirmed or probable pH1N1 

or ILI outside of work. One respondent with ILI reported only 

having known close contact with someone in the household or 

community with ILI. Five respondents with ILI reported multiple 

sources of exposure to individuals with confirmed or probable 

pH1N1 or ILI.

Of the 13 respondents reporting ILI, 10 reported working while ill 

with a range of 1–4 days. The most common reasons for working 

while ill are shown in Table 4 and included having a professional 

obligation to patients (n=4) and coworkers (n=4).
Page 12 Health Hazard Evaluation Report 2009-0206-3117

Results (continued)

We found no statistically significant differences in demographic 

characteristics (age, sex, race, Hispanic or Latino ethnicity) and 

rotation location during May 1–June 30, 2009, among respondents 

reporting a history of ILI compared to those not reporting ILI. 

In addition, we found no statistically significant differences 

in exposures to pH1N1 or ILI patients (either reported by the 

respondent or documented in the chart) or classification of high 

or low adherence to the minimum PPE recommendations among 

respondents reporting a history of ILI compared to those not 

reporting ILI. Respondents reporting a history of ILI were more 

likely to be a resident in their second post-graduate year than all 

other years of residency (OR = 6.79, 95% CI = 1.24, 34.56, n = 75) 

and to have been on a night float rotation in the 2-month period 

(OR = 8.62, 95% CI = 1.28, 54.42, n = 85).

We also found no statistically significant differences in 

demographic characteristics, exposures to pH1N1 (either reported 

by the respondent or documented in the chart), and classification 

of high or low adherence to the minimum PPE recommendations 

among respondents with a history of influenza A compared to 

those not reporting ILI. Respondents with a history of influenza 

A diagnosis reported a higher mean number of coworkers with 

confirmed or probable pH1N1 infection or ILI with whom they 

came in contact outside of work than those not reporting ILI (2.2 

coworkers vs. 0.56 coworkers, P < 0.01).

Twenty-five of 59 (42%) respondents at UH/HCH, 7 of 55 (13%) 

at GEWDVAMC, 28 of 32 (88%) at IMC, and 3 of 5 (60%) at 

PCMC knew the correct infection control precautions regarding 

Table 4. Most common reasons cited by respondents for working while ill

Reason Cited* No. Respondents

n = 10

I have a professional obligation to patients 4

I have a professional obligation to my coworkers 4

I did not think I would put patients at risk 3

I did not think I would put any coworkers at risk 2

I did not think I was contagious 2

I did not want to admit feeling sick 2

*Participants could cite more than one reason.
Health Hazard Evaluation Report 2009-0206-3117 Page 13

Results (continued) the minimum PPE recommendations. Eye protection was a 

component that respondents often did not know was included in a 

center’s infection control precautions. For example, at UH/HCH 

34 of 59 (57.6%) respondents either reported eye protection was 

not included in infection control precautions or that they did not 

know if it was included. Only 9 of 59 (15%) did not know gloves 

were included in infection control precautions.

Survey results regarding infection control knowledge and 

attitudes are shown in Table 5. Most respondents (71%–100%) 

who rotated at a particular associated medical center or who 

reported close contact with a patient with confirmed or probable 

pH1N1 or ILI at that center, reported knowing when patients 

were on influenza precautions at that particular medical center. 

Nearly all respondents expressed agreement that proper hand 

hygiene protected them (90%) and patients (91%) from acquiring 

influenza. Sixty-five percent of respondents expressed agreement 

that recommended influenza PPE was available near the rooms 

of patients in isolation. Eighty percent of respondents expressed 

agreement that PPE use protected patients from acquiring 

influenza, while 90% of respondents expressed agreement that 

PPE use protected them. However, 31% of respondents expressed 

agreement that PPE use interfered with patient care, and 67% 

felt confident that they knew how to use PPE. Fifty-three (60%) 

respondents indicated that surgical masks and N95 respirators 

are not equally protective in preventing the acquisition of 

influenza while 21 (24%) of respondents indicated they are equally 

protective, and 14 (16%) were neutral. Most of the 88 respondents 

considered intubation (98%), suctioning (97%), administration of 

nebulizing medications (77%), bronchoscopy (98%), acquisition 

of a nasopharyngeal sample (80%), and ventilation with bilevel 

positive airway pressure or continuous positive airway pressure 

(77%) to be aerosol-generating procedures.

Regarding infection control practices, 79 (90%) of respondents 

reported receiving the seasonal influenza vaccination the previous 

year between October 2008 and August 2009. Thirty-eight 

(43%) respondents reported having had N95 respirator training 

since the start of their program, 29 (33%) reported having had 

PAPR training since the start of their program, and 19 (22%) 

had undergone respirator fit testing between the start of their 

program and June 2009. Sixty-eight (77%) respondents reported 

always washing their hands before a patient encounter, while 71 

(81%) respondents reported always washing their hands after a 
Page 14 Health Hazard Evaluation Report 2009-0206-3117

Results (continued) patient encounter. None of the respondents reported never washing 

their hands before or after a patient encounter. Thirty-one (35%) 

of respondents reported taking antiviral medicine as influenza 

prophylaxis in the period May 1–June 30, 2009.

Table 5. Infection control knowledge and attitudes

Knowledge or Attitude Statement No. Respondents Who 

Expressed Agreement (%)

I know when patients are on influenza precautions at UH/HCH* 52/56 (93)

I know when patients are on influenza precautions at GEWDVAMC* 43/51 (84)

I know when patients are on influenza precautions at IMC* 20/28 (71)

I know when patients are on influenza precautions at PCMC* 5/5 (100)

Proper hand washing by me keeps me from getting the flu 81/88 (92)

Proper hand washing by me keeps patients from getting the flu 80/88 (91)

My PPE use keeps me from getting the flu 79/88 (90)

My PPE use keeps patients from getting the flu 70/87 (80)

Surgical masks and N95 respirators are equally protective in helping to protect 

me from getting the flu 21/88 (24)

Using recommended influenza PPE interferes with patient care 27/87 (31)

All recommended influenza PPE is available near the rooms of patients in 

isolation 57/88 (65)

The charge nurse or attending would remind me if I did not use PPE when 

caring for flu patients 49/88 (56)

I feel confident that I know how to use PPE 59/88 (67)

*Analysis limited to respondents who rotated at a particular medical center at any time during May1–June 30, 

 2009, according to residency program records, or respondents who reported close contact with a patient with 

 confirmed or probable pH1N1 or ILI at that center.

Fifty-three (60%) of the 88 respondents reported close contact with 

a confirmed or probable pH1N1 or ILI patient and provided PPE 

adherence information. Of those, we classified 19 (36%) as having 

high PPE adherence and 34 (64%) as having low PPE adherence.

Fifty-two respondents self reported whether or not they used all of 

the recommended PPE when in close contact with a confirmed or 

probable pH1N1 or ILI patient. Four respondents did not answer 

this specific question in the survey. Forty respondents answered 

that they did not always wear the recommended PPE and provided 

reasons. The most common reasons for not using recommended 

PPE were not knowing the patient had pH1N1 or ILI (n=22) and 

that PPE was unavailable near patients’ rooms (n=12). The most 

common reasons are shown in Table 6.
Health Hazard Evaluation Report 2009-0206-3117 Page 15

Results (continued)

We found no statistically significant differences in demographic 

characteristics (age, sex, race, Hispanic or Latino ethnicity) or 

rotation location among respondents classified as having high 

adherence to the minimum PPE recommendations compared to 

those classified as having low adherence. We did not have enough 

information to analyze agreement with knowing when patients 

were on influenza precautions at three of the four individual 

medical centers and their association with classification into 

high or low adherence to the minimum PPE recommendations. 

Agreement and disagreement (when dichotomized and neutral 

responses were excluded) with the other infection control 

knowledge and attitudes statements shown in Table 5 were not 

associated with classification into high or low adherence to the 

minimum PPE recommendations. In addition, knowledge of the 

correct infection control precautions regarding recommended PPE 

at each medical center was not associated with classification into 

high or low adherence to the minimum PPE recommendations.

Respondents classified as having high adherence to the minimum 

PPE recommendations were more likely to have performed or 

been present at an aerosol-generating procedure on a confirmed 

or probable pH1N1 patient (OR = 5.20, 95% CI = 1.54, 17.55). 

Table 6. The most common reasons cited by respondents for not using recommended PPE

Reason Cited* No. Respondents (%) 

n = 40

I did not know the patient had pH1N1 or ILI 22 (55)

The recommended PPE was not available near my patients’ rooms 12 (30)

I did not think I needed it for the activity I was performing 8 (20)

The facility ran out of the recommended PPE 7 (18)

I just entered the room for a brief time 5 (13)

I did not touch the patient 5 (13)

The facility did not provide the recommended PPE 4 (10)

I did not come within 6 feet of the patient 4 (10)

I was too busy to wear PPE 4 (10)

I did not know I was supposed to wear any PPE 3 (8)

I did not know which PPE I was supposed to wear 3 (8)

It is inconvenient to use recommended PPE when taking care of flu patients 4 (10)

* Respondents could cite more than one reason and cited one to seven reasons each.

† Respondents consisted of those who reported close contact with confirmed or probable pH1N1 or ILI patient 

 and self reported that they did not always wear recommended PPE.
Page 16 Health Hazard Evaluation Report 2009-0206-3117

Results (continued) They were also more likely to have been on an ICU rotation in the 

2-month period (OR = 3.43, 95% CI = 1.02, 11.56), but less likely to 

have been on a general inpatient wards rotation (OR = 0.22, 95% 

CI = 0.06, 0.80).

Twenty-four respondents reported being present at or performing 

any aerosol-generating procedures. Thirteen of the 24 (54%) were 

classified as high adherence, and 11 were classified as low adherence 

(46%) to the minimum PPE recommendations in Table 1. In 

this stratified analysis, the definitions of high and low adherence 

remained consistent with the original definitions. Since we did not 

differentiate aerosol-generating procedures from other close contact 

when asking about use of all recommended PPE components in the 

questionnaire, we were unable to ascertain adherence to the all of 

the minimum PPE components recommended for aerosol-generating 

procedures. However, of the 24 who reported being present at or 

performing aerosol-generating procedures, 3 (13%) reported never 

wearing appropriate respiratory protection (N95 or PAPR), one (4%) 

reported wearing it some of the time, 7 reported wearing it most of 

the time (29%), and 12 reported wearing it all the time (50%). One 

did not answer this question (4%).

For those not present at aerosol-generating procedures but reporting 

close contact with a patient with confirmed or probable pH1N1 

infection or ILI, 6 of 28 (21%) were classified as high adherence and 

22 (79%) were classified as low adherence. Being on an ICU rotation 

or general inpatient wards rotation were not significantly associated 

with PPE adherence when we removed those who reported having 

performed or been present at an aerosol-generating procedure on a 

confirmed or probable pH1N1 patient.

Site Visit 

Meetings with Housestaff and Fellows 

During our meetings with housestaff and fellows, we learned that, 

overall, caring for influenza patients during the spring and summer 

raised few issues for discussion among the housestaff and fellows. 

However, those that were raised included confusion about the 

appropriate evaluation and diagnosis of hospitalized patients with 

influenza symptoms. We heard about instances where patients’ rapid 

influenza antigen tests had returned with negative results, and the 

patients were taken out of appropriate isolation precautions, but 

later, the DFA or viral culture returned with a positive result. In these 
Health Hazard Evaluation Report 2009-0206-3117 Page 17

Results (continued) instances, the patients may have exposed others to the virus. Some 

of these instances occurred with patients transferred from another 

hospital. Housestaff also expressed concern with the length of time it 

took to receive influenza diagnostic test results with some reports of 

up to 2 weeks.

Some housestaff expressed confusion about the appropriate PPE 

that should be worn when entering the room of a patient with an 

undetermined febrile respiratory illness or confirmed, probable, 

or suspected pH1N1 influenza infection. They noted that PPE 

recommendations were not consistent across the four hospitals, 

especially regarding the use of gowns, eye protection, and respiratory 

protection. They voiced a variety of opinions about the availability of 

the recommended PPE near the patient’s room and the presence of 

appropriate signage depicting isolation. Some felt that eye protection 

was not necessary when treating influenza patients. They had a 

variety of opinions on whether to use surgical masks or respirators 

in certain instances. Some asserted that surgical masks were more 

comfortable to wear especially for longer periods. Some felt that N95s 

were hot, uncomfortable, muffled their voices, and caused more 

difficulty because of greater breathing resistance, but others felt that 

N95 respirators or PAPRs were also tolerable. A few of the housestaff 

noted that it is difficult to auscultate (listening for sounds made by 

internal organs) a patient while wearing a PAPR. Some also expressed 

concern they had not been fit tested to wear an N95 respirator during 

the residency or fellowship, and many reported they had not been 

trained on the proper use of PAPRs.

Some housestaff voiced concerns that the initially recommended 

furlough period of 7 days for ill HCP was too long, noting that this 

might actually deter them from reporting that they were ill. While 

the “pull system” (where residents are “pulled” from other rotations 

in the hospital to replace ill housestaff) in place at the residency is 

an effective method of dealing with absences, the housestaff voiced 

concern and reluctance in having one of their colleagues cover for 

them. Some housestaff did report being exposed to other housestaff 

who were ill and at work.

Meetings with Medical Center Staff

During our meetings, we learned that all four medical centers were 

using the occupational health hierarchy of controls approach to 

prevent influenza transmission within their settings and to prevent 

exposure of HCP. Comprehensive programs were in place, and 
Page 18 Health Hazard Evaluation Report 2009-0206-3117

Results (continued)

Prior to the pH1N1 pandemic, the seasonal influenza vaccination 

rates of employees at the four medical centers ranged from 69%—

90%. Some of the hospitals had implemented creative methods 

to increase vaccination rates, including badge scanning systems, 

influenza vaccine clinics, drive-through vaccination programs, and 

bringing vaccine carts to each unit. We learned that most of the 

medical centers had secret observers who monitored compliance 

with hand hygiene. One of the medical centers placed this hand 

hygiene data in graph form in locations visible to patients and staff 

as the screensavers for all hospital computers (Figure 4).

During our meetings with staff, we also learned about the logistical 

issues associated with the CDC interim infection control guidance 

[CDC 2009i]. First, the limited supply of N95 respirators was a 

significant problem for at least three hospitals. Staff reported short 

supplies of N95 respirators since the pandemic began. A major 

manufacturer had not fulfilled its contracts, and N95 respirators 

had been on back order since June 2009. In addition, the price 

of the N95 respirators had increased substantially since the 

beginning of the pandemic. Two of the hospitals reported that in 

Figure 3. Photograph of table containing alcohol-based hand sanitizer, 

surgical masks, and instructions for their use at the main entrance of one 

medical center.

Figure 2. Photograph of patient room 

door containing recommended PPE 

and appropriate signage at one 

medical center.

innovative methods of infection control had been implemented 

with respect to engineering and administrative controls (examples 

in Figures 2 and 3).
Health Hazard Evaluation Report 2009-0206-3117 Page 19

Results (continued)

Figure 4. Photograph of screensaver containing hand hygiene 

compliance data displayed on a hospital computer at one medical 

center.

May and June 2009, boxes of N95 respirators and surgical masks 

had disappeared. Some of the hospitals were also making PAPRs 

available for use by employees. However, it was reported that the 

price of PAPRs had more than tripled since the pandemic began 

and that this had presented an additional barrier to obtaining the 

appropriate PPE.

We also learned that none of the medical centers’ respiratory 

protection programs included all employees with patient contact. 

Before this pH1N1 pandemic, HCP wore N95 respirators 

mainly when in contact with patients with known or suspected 

active tuberculosis. Because Salt Lake City is an area with a low 

incidence of tuberculosis, most of the medical centers included 

in their respiratory protection programs only those employees 

with patient contact in designated units for tuberculosis patients. 

Since the pandemic began, the medical centers found it difficult 

to conduct respirator fit testing of all employees with potential 

contact to known or suspected pH1N1 patients because of time 

and financial constraints, scheduling difficulties, and limited 

number of personnel trained to conduct fit testing. Additionally, 

some employees had been previously fit tested for one model of 

N95 respirator, but when supplies ran out, needed to be fit tested 

for a different model. The cost of fit-testing kits had increased 

significantly. According to two of the medical centers, the high 
Page 20 Health Hazard Evaluation Report 2009-0206-3117

Results (continued) cost of the kits and the time necessary to conduct the testing was 

considered prohibitive.

During our meetings with the staff, they also discussed the difficulty 

in complying with the 7-day furlough period for ill employees 

recommended at that time. Some employees were frustrated at not 

being allowed to come back to work earlier. Two of the medical 

centers provided separate vacation and sick leave, but the other 

two provided general paid time off, which included both vacation 

and sick leave. In some instances, employees had already used all of 

their paid time off before they became ill. One medical center had 

explored alternative work arrangements such as teleworking but noted 

that it was not possible to offer this to everyone and thus was not 

implemented.

Most respondents reported exposure to individuals with confirmed or 

probable pH1N1 or ILI either at work or outside of work early in the 

pandemic. Most respondents (65%) reported having contact with a 

patient with confirmed or probable pH1N1 or ILI. Respondents also 

reported contact with ill coworkers both at work (52%) and outside 

of work (32%).

The prevalence of ILI among responding internal medicine housestaff 

and cardiology and pulmonary and critical care fellows in May–June 

2009, was 15%. Eight of the 13 cases were clustered between the 

dates of June 21–23, 2009. Healthcare-associated acquisition of 

infection was likely in two cases via patient to physician contact and 

likely in two cases via physician-to-physician contact at work. One 

case was likely due to exposure to ill coworkers outside of work. The 

other respondents with ILI either reported none or multiple sources 

of exposure to pH1N1 or ILI, making it difficult to determine their 

source of exposure. Our findings are consistent with the report of 

26 cases among HCP where transmission of pH1N1 virus occurred 

in both healthcare and community settings [CDC 2009j]. Given 

the date proximity of the resident dinner to the cluster of cases, it is 

plausible that attendance at the resident dinner facilitated the spread 

of illness.

Most responding physicians (77%) with ILI reported working 

while ill. In addition, over half (52%) of the responding physicians 

reported having contact with a coworker with confirmed or probable 

pH1N1 or ILI at work. These results highlight the need for prompt 

identification and exclusion of ill housestaff and fellows from work.

Discussion
Health Hazard Evaluation Report 2009-0206-3117 Page 21

Discussion (continued) During our meetings with housestaff and fellows, we learned about 

their frustration with the poor sensitivity of the rapid influenza 

antigen tests, which possibly contributed to their exposure to pH1N1 

virus. The overall sensitivity of the rapid influenza antigen tests in 

diagnosing pH1N1 infection is low, ranging from 40%–69% [CDC 

2009c]. One investigation of its performance during two school 

outbreaks found that it had a negative predictive value of 32% [CDC 

2009k]. Thus, a negative result does not rule out infection with 

pH1N1 virus.

Our findings also reveal gaps in knowledge about correct infection 

control precautions regarding PPE at each hospital. We found a 

wide range of responding physicians (13%–88%) who knew which 

PPE were included in infection control precautions for caring for 

patients with ILI (see Table 1) across medical centers. In particular, 

many responding physicians did not recognize that eye protection 

was included the medical center’s infection control precautions at 

three of the medical centers. In contrast, most responding physicians 

recognized that glove use was a component of infection control 

precautions at all medical centers. The vast majority of respondents 

agreed that hand hygiene and PPE use are effective prevention 

methods in influenza transmission. Much lower percentages of 

respondents (22%–43%) reported having had respirator training or 

fit testing since the start of their program.

The rate of seasonal influenza vaccination in the previous year was 

high in this group of responding physicians at 90%. This is consistent 

with the seasonal influenza vaccination rates of all employees at 

the four medical centers during the previous year reported during 

our meetings, which ranged from 62%–90% and demonstrates the 

commitment to this administrative control by the medical centers. 

The seasonal vaccination rate of 90% among respondents is far 

greater than overall influenza vaccination rates for HCP nationwide, 

which have never exceeded 49% in any season since 1989, according 

to estimates from the National Health Interview Survey [Walker et al. 

2006; Caban-Martinez et al. 2010].

Most ILI or pH1N1 patient-exposed responding physicians (64%) 

were classified as having low adherence to the minimum PPE 

recommendations in accordance with hospital policies. Lack of 

awareness of a patient having pH1N1 or ILI and reporting that PPE 

was unavailable near patients’ rooms were the most common reasons 

cited for not using recommended PPE. Although most respondents 

agreed that they knew when patients were on influenza precautions 
Page 22 Health Hazard Evaluation Report 2009-0206-3117

Discussion (continued) at the four medical centers, the percentages ranged from 71%–100%, 

showing that improvements can still be made at some centers. Only 

22% of respondents reported having been fit tested for a respirator 

during their training prior to the pH1N1 pandemic. Our discussions 

with medical center staff also revealed problems with the supply of 

N95 respirators.

We classified 36% of responding physicians as having high adherence 

to the minimum PPE recommendations; this is lower than that 

found by Daugherty et al., who found that 62% of critical care 

HCPs reported PPE adherence >80% [Daugherty et al. 2009]. Their 

classification of PPE adherence differed from ours. In that study, 

respondents were asked to report a percentage of time as adhering 

to PPE use and were classified as having high adherence if >80%. In 

addition, their study population only included critical care HCPs, 

who may have higher PPE adherence rates.

Physicians classified as having high adherence to the minimum

PPE recommendations were more likely to have performed or 

been present at an aerosol-generating procedure on a confirmed 

or probable pH1N1 patient and have been on an ICU rotation. 

Physicians classified as having low adherence to the minimum 

PPE recommendations were more likely to have been on a general 

inpatient wards rotation. This suggests a lack of emphasis or training 

on PPE use when caring for noncritically ill pH1N1 or ILI patients.

Our evaluation was subject to some limitations. Our response rate 

was 42% despite multiple e-mail reminders to the housestaff and 

fellows. Thus, our results may not be representative of all physicians 

in these programs. However, housestaff in all years of training in 

the internal medicine residency and fellows from each program 

were represented in our sample. Although 13 (15%) of respondents 

reported symptoms of ILI, two additional internal medicine residents 

were identified by the residency program as being absent with ILI 

symptoms during May 1–June 30, 2009. These residents did not 

complete a survey and were not included in our evaluation. Our 

sample size of respondents reporting ILI and of respondents with a 

laboratory confirmed diagnosis of influenza A also may have been 

too small to detect statistically significant differences. We note that 

this evaluation was exploratory, many analyses were performed to 

examine possible relationships, and some significant findings may 

have occurred by chance. Thus, our results might be best used for 

hypothesis generation.
Health Hazard Evaluation Report 2009-0206-3117 Page 23

Discussion (continued) Also, though the period of highest absenteeism was in June 

2009, we did not receive the HHE request until August 2009. 

Thus, respondents’ ability to recall may have affected some of 

our results. Our classification of adherence to the minimum PPE 

recommendations was based on self-reported behaviors by survey 

respondents. Henry et al. demonstrated that self-reported rates 

for PPE use, especially gloves, masks, and gowns were significantly 

higher for all emergency department personnel when compared to 

observed rates [Henry et al. 1994]. Therefore, our findings that 36% 

of respondents fit into the high adherence to the minimum PPE 

recommendations group may be an overestimation.

Five (71%) of the 13 respondents who reported ILI symptoms sought 

medical care from a healthcare provider, underwent laboratory 

testing, and had a laboratory-confirmed diagnosis of influenza A 

by either viral culture or DFA. Following the guidance of the Utah 

Department of Health and the Utah Public Health Laboratories 

[UDOH 2009d], these five laboratory specimens did not undergo 

further subtyping by RT-PCR. This leads to uncertainty as to whether 

these five respondents were truly infected with the pH1N1 virus. 

However, CDC surveillance data from May 24–June 27, 2009, shows 

that approximately 82%–99% of all influenza viruses reported to 

CDC nationwide during this period were pH1N1 viruses. [CDC 

2009d,e,f,g,h]. Utah Department of Health data show that 90%–95% 

of all influenza viruses tested by the Utah Public Health Laboratory 

were pH1N1 viruses [UDOH 2009a,b,c]. Given these local and 

national numbers, it is likely that these respondents with a diagnosis 

of influenza A were infected with the pH1N1 virus.

Most internal medicine housestaff and cardiology and pulmonary 

and critical care fellows reported exposure to pH1N1 or ILI at work, 

from both patients and coworkers. The occupational health hierarchy 

of controls approach to prevent influenza transmission was being 

used to prevent exposure to HCP. Innovative methods of infection 

control have been implemented with respect to engineering and 

administrative controls. However, significant gaps in infection control 

knowledge, exclusion of ill housestaff and fellows from work, and 

adherence to PPE use exist.

Conclusions
Page 24 Health Hazard Evaluation Report 2009-0206-3117

On the basis of our findings, we recommend the actions listed below 

to create a more healthful workplace. Our recommendations are 

based on the hierarchy of controls approach and are intended for the 

residency and fellowship programs and/or the associated medical 

centers. This approach groups actions by their likely effectiveness 

in reducing or removing hazards. In most cases, the preferred 

approach is to eliminate hazardous materials or processes and install 

engineering controls to reduce exposure or shield employees. If they 

are not effective or feasible, administrative measures and/or personal 

protective equipment may be needed. This list is not meant to be 

comprehensive, and more information on infection control measures 

can be found on the CDC website at http://www.cdc.gov/flu/

professionals/infectioncontrol/healthcaresettings.htm.

Elimination 

Eliminating the potential source of exposure is a highly effective 

means for reducing hazards and ranks highest in the hierarchy of 

controls.

1. Institute procedures for tracking housestaff and fellows who 

are ill and absent.

a. Encourage housestaff and fellows to self assess for 

symptoms and report symptoms to their attending 

physicians, their program, and the chief residents (if 

applicable).

b. Exclude housestaff and fellows with febrile respiratory 

illness from work according to the most recent CDC 

guidance, which can be found on the CDC website at 

http://www.cdc.gov/flu/professionals/infectioncontrol/

healthcaresettings.htm.

c. Develop a written plan for staffing of housestaff and 

fellows in the event of a pandemic or other emergency.

d. Encourage housestaff and fellows with febrile respiratory 

illness to avoid social events outside of work.

2. Continue procedures for managing visitors to the facility 

because visitors could be a source of influenza. Post signage 

at entry points in appropriate languages that educate visitors 

on the symptoms of influenza and instruct them not to enter 

if ill. Consider establishing a mechanism to screen visitors for 

influenza symptoms upon entry to the medical center or entry 

into the patient unit. Limit visitors of patients in isolation for 

influenza to those necessary for the patient’s emotional wellbeing and care.

Recommendations
Health Hazard Evaluation Report 2009-0206-3117 Page 25

Recommendations

(continued) Engineering Controls 

Engineering controls reduce exposures to employees by removing the 

hazard from the process or placing a barrier between the hazard and 

the employee. Engineering controls are very effective at protecting 

employees without placing primary responsibility of implementation 

on the employee.

1. Conduct aerosol-generating procedures in an airborne 

infection isolation room, whenever possible, to prevent the 

spread of aerosols to other parts of the facility.

2. Continue to install and use hands-free soap and water 

dispensers and receptacles for garbage and linens to minimize 

environmental contact.

Administrative Controls 

Administrative controls are management-dictated work practices 

and policies to reduce or prevent exposures to workplace hazards. 

The effectiveness of administrative changes in work practices 

for controlling workplace hazards is dependent on management 

commitment and employee acceptance. Regular monitoring and 

reinforcement is necessary to ensure that control policies and 

procedures are not circumvented in the name of convenience or 

production.

1. Provide education and training to the housestaff and fellows 

at least annually about the evaluation, diagnosis, treatment, 

and complications of patients with symptoms of influenza; 

the recommended isolation precautions at each medical 

center; proper hand hygiene; and the proper donning, use, 

and removal of recommended PPE. Methods to conduct this 

training include conferences, other teaching sessions, and 

computer-based modules.

2. Provide specific instructions to housestaff emphasizing the 

importance of not reporting to work when ill, and have a 

discussion of scheduling plans for when illness occurs and for 

when a pandemic or other emergency occurs.

3. Continue to require housestaff and fellows to receive the 

annual seasonal influenza vaccine as part of the comprehensive 

influenza infection control strategy. Instituting an employer 

requirement of influenza vaccine has been associated with 

higher rates of seasonal influenza vaccination compared 
Page 26 Health Hazard Evaluation Report 2009-0206-3117

Recommendations

(continued) with rates among HCP whose employers neither required 

nor recommended seasonal influenza vaccination [CDC 

2010a]. The 2010–2011 trivalent vaccines will contain A/

California/7/2009 (H1N1)-like, A/Perth/16/2009 (H3N2)-

like, and B/Brisbane/60/2008-like antigens [CDC 2010c]. 

Make the vaccine available to all housestaff and fellows at 

their assigned medical centers and consider administering 

the vaccine to housestaff and fellows before or after 

morning report, grand rounds, lectures, or conferences. The 

residency and fellowship programs should keep track of these 

vaccination rates.

4. Include housestaff and fellows rotating at each medical center 

on e-mail disseminated by each medical center to its employees 

regarding influenza and general infection control information.

5. Place signs indicating appropriate isolation precautions outside 

patients’ rooms as soon as patients are placed in the rooms.

6. Limit HCP entering the room of a patient in isolation 

precautions for influenza to those performing patient care 

activities. Attending physicians should consider eliminating 

bedside teaching rounds for those patients in isolation and 

instead present and discuss the case outside the patient’s 

room.

7. The overall sensitivity of the rapid influenza antigen tests in 

diagnosing pH1N1 infection is low, ranging from 40%–69% 

[CDC 2009c,k]. A negative result does not rule out infection 

with pH1N1 virus. Evaluate patients with illnesses compatible 

with pH1N1 infection but a negative rapid test based on level 

of clinical suspicion. This also applies to patients transferred 

from outside hospitals. More information on diagnostic tests 

for pH1N1 influenza can be found at http://www.cdc.gov/

h1n1flu/guidance/rapid_testing.htm and http://www.cdc.

gov/h1n1flu/specimencollection.htm.

Personal Protective Equipment 

PPE is the least effective means for controlling employee exposures. 

Proper use of PPE requires a comprehensive program, and calls for a 

high level of employee involvement and commitment to be effective. 

The use of PPE requires the choice of the appropriate equipment to 

reduce the hazard and the development of supporting programs such 

as training, change-out schedules, and medical assessment if needed. 
Health Hazard Evaluation Report 2009-0206-3117 Page 27

Recommendations

(continued) PPE should not be relied upon as the sole method for limiting 

employee exposures. Rather, PPE should be used until engineering 

and administrative controls can be demonstrated to be effective in 

limiting exposures to acceptable levels.

1. Train housestaff and fellows on medical center PPE 

requirements, and emphasize PPE use to those who care for 

both critically ill and noncritically ill pH1N1 and ILI patients.

2. Develop, implement, and maintain a respiratory protection 

program for all housestaff and fellows to protect against 

airborne infectious agents. Train, medically clear, and fit 

test all housestaff and fellows as described in the OSHA 

Respiratory Protection Standard (29 CFR 1910.134).

3. Make PPE, including gloves, gowns, surgical masks, N95 

respirators, and eye protection readily available according to 

hospital guidelines near patient rooms. Designate individuals 

responsible for stocking these supplies on each floor or wing. 

Housestaff and fellows who encounter a lack of available 

PPE should alert appropriate floor personnel or seek out 

appropriate PPE from an alternate location.

4. Coordinate with a designated person in charge at each medical 

center to ensure an adequate inventory of N95 respirators 

for emergency purposes. As part of the respiratory protection 

program, conduct annual audits of respirators (which have 

finite shelf-lives) and ensure adequate sizing for current 

housestaff.

Ajzen I [1991]. The theory of planned behavior. Organ Behav Hum 

Decis Process 50(2):179–211.

Caban-Martinez AJ, Lee DJ, Davila EP, LeBlanc WG, Arheart KL, 

McCollister KE, Christ SL, Clarke T, Fleming LE [2010]. Sustained 

low influenza vaccination rates in US healthcare workers. Prev Med 

50(4):210–212.

CDC [2009a]. 2009 H1N1 early outbreak and disease characteristics 

[http://www.cdc.gov/h1n1flu/surveillanceqa.htm]. Date accessed: 

September 2010.

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Health Hazard Evaluation Report 2009-0206-3117 Page 31

Acknowledgments and

Availability of Report

The Hazard Evaluations and Technical Assistance Branch 

(HETAB) of the National Institute for Occupational Safety and 

Health (NIOSH) conducts field investigations of possible health 

hazards in the workplace. These investigations are conducted 

under the authority of Section 20(a)(6) of the Occupational Safety 

and Health Act of 1970, 29 U.S.C. 669(a)(6) which authorizes 

the Secretary of Health and Human Services, following a written 

request from any employer or authorized representative of 

employees, to determine whether any substance normally found 

in the place of employment has potentially toxic effects in such 

concentrations as used or found. HETAB also provides, upon 

request, technical and consultative assistance to federal, state, and 

local agencies; labor; industry; and other groups or individuals to 

control occupational health hazards and to prevent related trauma 

and disease.

The findings and conclusions in this report are those of the 

authors and do not necessarily represent the views of NIOSH. 

Mention of any company or product does not constitute 

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Furthermore, NIOSH is not responsible for the content of these 

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This report was prepared by Marie A. de Perio, Scott E. Brueck, 

and Charles A. Mueller of HETAB, Division of Surveillance, 

Hazard Evaluations and Field Studies. Health communication 

assistance was provided by Stefanie Evans. Editorial assistance was 

provided by Ellen Galloway. Desktop publishing was performed by 

Robin Smith.

Copies of this report have been sent to employee and management 

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Below is a recommended citation for this report:

NIOSH [2010]. Health hazard evaluation report: evaluation of 2009 pandemic 

influenza A (H1N1) virus exposure among internal medicine housestaff and fellows, 

Salt Lake City, UT. By de Perio MA, Brueck SE, Mueller CA. Cincinnati, OH: U.S. 

Department of Health and Human Services, Centers for Disease Control and 

Prevention, National Institute for Occupational Safety and Health, NIOSH HETA

No. [HETA 2009-0206-3117].

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