For more information: www.cdc.gov/COVID19

Nancy McClung, PhD, RN

ACIP Meeting

August 26, 2020

Epidemiology of Individuals at 

Increased Risk of COVID-19 

Disease 

CDC Coronavirus Disease 2019 Response
Outline

 Overview of U.S. COVID-19 Epidemiology

 Epidemiology of Individuals at Increased Risk of Severe COVID-19 Disease

– Older Adults (aged 65 years or older)

– Adults with Underlying Medical Conditions (aged 18 years or older)

2
Overview of U.S. COVID-19

Epidemiology
United States COVID-19 Cases by County

https://www.cdc.gov/covid-data-tracker/index.html

January 21 to August 23, 2020

4
5 https://www.cdc.gov/covid-data-tracker/index.html#trends

Trends in Number of COVID-19 Cases in the US

January 21 to August 23, 2020

Jan 22 Apr 2 Jun 13 Aug 23

0

k 10

k 20

k 30

k 40

k 50

k 60

k 70

k 80

Jan 22 Apr 2 Jun 13 Aug 23
0

5

10

15

20

25

30

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

Percent Positive

Specimens Tested

Week

U.S. State and Local Public Health Laboratories Reporting to CDC: 

Number of Specimens Tested and Percent Positive for SARS-CoV-2

March 1, 2020 – August 15, 2020

Specimen tested: Age Unk

Specimen tested: 65+ yrs

Specimen tested: 50-64 yrs

Specimen tested: 18-49 yrs

Specimen tested: 5-17 yrs

Specimen tested: 0-4 yrs

% pos.: overall

% pos.: 0-4 yrs

% pos.: 5-17 yrs

% pos.: 18-49 yrs

% pos.: 50-64 yrs

% pos.: 65+ yrs

https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covidview/index.html 6

Week 33

6.6%
0

5

10

15

20

25

30

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

Percent Positive

Specimens Tested

Week

Select Commercial Laboratories Reporting to CDC: 

Number of Specimens Tested and Percent Positive for SARS-CoV-2

March 29, 2020 – August 15, 2020

Specimen tested: Age Unk

Specimen tested: 65+ yrs

Specimen tested: 50-64 yrs

Specimen tested: 18-49 yrs

Specimen tested: 5-17 yrs

Specimen tested: 0-4 yrs

% pos.: overall

% pos.: 0-4 yrs

% pos.: 5-17 yrs

% pos.: 18-49 yrs

% pos.: 50-64 yrs

% pos.: 65+ yrs

Week 33

6.3%

https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covidview/index.html 7
United States COVID-19 Deaths by County

January 21 to August 23, 2020

https://www.cdc.gov/covid-data-tracker/index.html 8
Jan 22 Apr 2 Jun 13 Aug 23

0

500

k1

.5k 1

k2

.5k 2

k3

.5k 3

k4

.5k 4

k5

.5k 5

k6

.5k 6

9 https://www.cdc.gov/covid-data-tracker/index.html#trends

Trends in Number of COVID-19 Deaths in the US

January 21 to August 23, 2020

Jan 22 Apr 2 Jun 13 Aug 23
COVID-19 Epidemiology of 

Adults Aged 65 Years or Older
11

Adults aged 65 years and older and people of any age with 

certain underlying medical conditions are at increased risk for 

severe illness from COVID-19:
12

 Hospitalization

 Intensive Care Unit (ICU) care

 Intubation or mechanical ventilation

 Death

Adults aged 65 years and older and people of any age with 

certain underlying medical conditions are at increased risk for 

severe illness from COVID-19:
In the United States, adults aged 65 years or older represent 16% of 

COVID-19 cases, but nearly 80% of COVID-19 deaths

13

35 30 25 20 15 10 5 0

Percentage of cases

0 5 10 15 20 25 30 35

Percentage of deaths

https://www.cdc.gov/covid-data-tracker/index.html#demographics

Updated as of 8/24/20. Data are based on COVID-19 case-level data reported by state and territorial jurisdictions to the Centers for Disease Control and Prevention (CDC). The 

numbers are confirmed and probable COVID-19 cases as reported by U.S. states, U.S. territories, New York City, and the District of Columbia from the previous day. 

*Data from 4,272,205 cases. Age group was available for 

4,109,540 (96%) cases

*Data from 131,692 deaths. Age group was available for 131,676 

(99%) deaths

0-17 Years

18-29 Years

30-39 Years

40-49 Years

50-64 Years

65-74 Years

75-84 Years

85+ Years
COVID-NET: 

Hospitalization Surveillance from 14 States

States participating in COVID-NET Surveillance network collecting 

hospitalization data

• Catchment area ~10% of US population

• Patients must be a resident of the surveillance 

area and have a positive SARS-CoV-2 test within 

14 days prior to or during hospitalization

• Charts reviewed by trained surveillance officers

and data include underlying medical conditions

MMWR April 17, 2020

https://www.cdc.gov/mmwr/volumes/69/wr/mm6915e3.htm

COVID-NET = COVID-19-Associated Hospitalization Surveillance Network 

14
COVID-NET: Older adults aged 65 years or older have the highest cumulative rate of 

COVID-19 associated hospitalizations*

15

*COVID-19 associated hospitalizations reported to Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) surveillance system 

from March 1-August 15, 2020. COVID-NET is a population-based surveillance system that collects data on laboratory-confirmed COVID-19-associated hospitalizations 

among children and adults through a network of over 250 acute-care hospitals in 14 states. https://gis.cdc.gov/grasp/COVIDNet/COVID19_3.html

0

50

100

150

200

250

300

350

400

450

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

COVID-19 Hospitalization Rates 

per 100,000 population

Week

65+ years

50-64 years

18-49 years

March 1-August 15, 2020
16

COVID-NET: Adults aged 50 years and older are more likely to have severe outcomes 

during COVID-19 associated hospitalizations compared to adults aged 18-49 years

0

10

20

30

40

50

Intensive care unit Mechanical ventilation In-hospital death

Weighted Percent of Hospitalized Adults 

18-49 years 50-64 years 65+ years

*COVID-19 associated hospitalizations reported to Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) surveillance system between 

March 1 and August 15, 2020. The denominator for intensive care unit, mechanical ventilation, in-hospital mortality, and discharge diagnoses is restricted to cases who are no longer 

hospitalized and who have complete medical chart reviews. COVID-NET is a population-based surveillance system that collects data on laboratory-confirmed COVID-19-associated 

hospitalizations among children and adults through a network of over 250 acute-care hospitals in 14 states. https://gis.cdc.gov/grasp/COVIDNet/COVID19_5.html

March 1-August 15, 2020
COVID-NET: Among 2,491 adults with COVID-19 associated hospitalization between 

March 1 and May 2, 2020, older age was the strongest, independent risk factor for inhospital death

85+ years vs 18-39 years

75–84 years vs 18-39 years

65–74 years vs 18-39 years

50-64 years vs 18-39 years

Male

Immunosuppression

Renal disease

Chronic Lung Disease

Cardiovascular Disease

Neurologic disorder

Diabetes

10.98

7.67

5.77

3.11

1.3

1.39

1.33

1.31

1.28

1.25

1.19

-5 0 5 10 15 20

Adjusted Rate Ratios and 95% Confidence Intervals

*COVID-NET Surveillance; Final model adjusted for age, sex, race/ethnicity, smoker, hypertension, obesity, diabetes, chronic lung disease, cardiovascular disease, neurologic 

disease, renal disease, immunosuppression, hematologic disorders, and rheumatologic or autoimmune disease. Kim et al, 2020, https://academic.oup.com/cid/advancearticle/doi/10.1093/cid/ciaa1012/5872581 17
Gupta et al, July 2020; https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2768602

*Modified from Gupta et al, 2020, JAMA Int Med. Multivariable risk model for 28-day death after ICU admission. Model adjusted for age, sex, race, other patient-level 

characteristics such as comorbidities, symptoms, and body mass index, and hospital-level characteristics such as number of ICU beds.

Multi-center U.S. cohort study: Among 2,215 adults with COVID-19 associated intensive 

care unit(ICU)-admission between March 4 and April 4, 2020, older age was the 

strongest, independent risk factor for in-hospital death within 28 days of admission

18
COVID-19 Epidemiology of Individuals with 

Underlying Medical Conditions
20

COVID-NET: Underlying conditions among adults aged 18 years or older 

with COVID-19 associated hospitalizations

*COVID-19 associated hospitalizations reported to Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) surveillance system 

from March 1-August 15, 2020. The denominator is restricted to cases with a discharge disposition and for which chart review was completed. COVID-NET is a populationbased surveillance system that collects data on laboratory-confirmed COVID-19-associated hospitalizations among children and adults through a network of over 250 acutecare hospitals in 14 states. https://gis.cdc.gov/grasp/COVIDNet/COVID19_5.html

March 1-August 15, 2020

0 10 20 30 40 50 60 70

Autoimmune disease

Gastrointestinal/liver disease

Immune suppression

Asthma

Renal disease

Chronic lung disease

Neurologic disease

Cardiovascular disease

Diabetes

Obesity

Hypertension

Weighted Percent of Hospitalized Persons
COVID-NET: The most common underlying medical conditions among 

hospitalized adults varies by age group

21

*COVID-19 associated hospitalizations reported to Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) surveillance system 

between March 1 and August 15, 2020. The denominator is restricted to cases with a discharge disposition and for which chart review was completed. COVID-NET is a 

population-based surveillance system that collects data on laboratory-confirmed COVID-19-associated hospitalizations among children and adults through a network of 

over 250 acute-care hospitals in 14 states. https://gis.cdc.gov/grasp/COVIDNet/COVID19_5.html

March 1-August 15, 2020

18-49 years 50-64 years 65+ years 

Obesity (61.5%) Hypertension (60.5%) Hypertension (77.8%)

Hypertension (27.2%) Obesity (56.5%) Cardiovascular disease (55.2%)

Diabetes (21.8%) Diabetes (37.9%) Neurologic disease (42.5%)

Asthma (14.1%) Cardiovascular disease (26.3%) Diabetes (41.8%)

Chronic lung disease (9.8%) Chronic lung disease (18.8%) Obesity (34.6%)
22

COVID-NET: Over 60% of hospitalized adults had 3 or more of the selected 

underlying medical conditions*

*Defined as one or more of hypertension, obesity, diabetes, cardiovascular disease, neurologic disease, chronic lung disease, renal disease, asthma, immune suppression, 

gastrointestinal/liver disease, and autoimmune disease. **Unadjusted for age or other demographic variables.

COVID-19 associated hospitalizations reported to Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) surveillance system from 

March 1-August 15, 2020. The denominator is restricted to cases with a discharge disposition and for which chart review was completed. COVID-NET is a population-based 

surveillance system that collects data on laboratory-confirmed COVID-19-associated hospitalizations among children and adults through a network of over 250 acute-care 

hospitals in 14 states. 

March 1-August 15, 2020

0 10 20 30 40 50 60 70

No conditions

1 condition only

2 conditions only

3 or more conditions

Weighted Percentage of Hospitalizations**
23

COVID-NET: Of hospitalized adults that died, nearly 80% had 3 or more 

underlying medical conditions*

*Defined as one or more of hypertension, obesity, diabetes, cardiovascular disease, neurologic disease, chronic lung disease, renal disease, asthma, immune suppression, 

gastrointestinal/liver disease, and autoimmune disease. **Unadjusted for age or other demographic variables. Each severe outcome adds up to 100 percent.

COVID-19 associated hospitalizations reported to Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) surveillance system from 

March 1-August 15, 2020. The denominator is restricted to cases with a discharge disposition and for which chart review was completed. COVID-NET is a population-based 

surveillance system that collects data on laboratory-confirmed COVID-19-associated hospitalizations among children and adults through a network of over 250 acute-care hospitals 

in 14 states. 

March 1-August 15, 2020

0 20 40 60 80 100

ICU admision

Mechanical ventilation/intubation

Death

Weighted Percent of Hospitalized Persons**

3 or more conditions

2 conditions only

1 condition only

No conditions
24

COVID-NET: Of hospitalized adults 65 years or older, 80% had 3 or more 

underlying medical conditions*

*Defined as one or more of hypertension, obesity, diabetes, cardiovascular disease, neurologic disease, chronic lung disease, renal disease, asthma, immune suppression, 

gastrointestinal/liver disease, and autoimmune disease. **Unadjusted for other demographic variables. Each age group adds to 100 percent. 

-COVID-19 associated hospitalizations reported to Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) surveillance system 

from March 1-August 15, 2020. The denominator is restricted to cases with a discharge disposition and for which chart review was completed. COVID-NET is a populationbased surveillance system that collects data on laboratory-confirmed COVID-19-associated hospitalizations among children and adults through a network of over 250 

acute-care hospitals in 14 states. 

March 1-August 15, 2020

0 20 40 60 80 100

18-49 years

50-64 years

65+ years

Weighted Percentage of Hospitalizations**

3 or more conditions

2 conditions only

1 condition only

No conditions
25

 COVID-19-Associated Hospitalization Surveillance Network (COVID-NET)

– 14 sites representing 10% of U.S. population

– Community-dwelling adults (≥ 18 years of age) prior to hospitalization with chart-abstracted 

data on underlying medical condition (N=5,416)

– March 1 – June 23, 2020 

 Behavioral Risk Factor Surveillance System (BRFSS)

– Annual, cross-sectional survey on health behaviors and self-reported underlying 

medical conditions among community-dwelling adults (≥ 18 years of age) in all 50 statues, D.C., 

and 3 U.S. territories

– Weighted to be representative of population residing in COVID-NET catchment area

Population-based data sources

https://medrxiv.org/cgi/content/short/2020.07.27.20161810v1

Are underlying medical conditions an independent risk factor for COVID-19-

associated hospitalization in adults aged 18 years or older?
26 https://medrxiv.org/cgi/content/short/2020.07.27.20161810v1

 Prevalence of underlying medical conditions was calculated among COVID-NET hospitalized adults, 

COVID-NET catchment area, and nationwide

 Unadjusted and adjusted rate ratios and 95% confidence intervals (CIs) associated with hospitalization

– Generalized Poisson regression models with a scaled deviance term to account for overdispersion

– Multivariable models included an individual underlying medical condition and were adjusted for 

age, sex, and race/ethnicity

 Non-overlapping 95% CIs were considered to represent statistically significant differences

Statistical Analysis

Are underlying medical conditions an independent risk factor for COVID-19-

associated hospitalization in adults aged 18 years or older?
The prevalence of underlying medical conditions was greater among adults with 

COVID-19 associated hospitalizations compared to COVID-NET catchment areas

§Estimates for hypertension from COVID-NET Catchment Area and Nationwide BRFSS estimates are from 2017, Obesity=BMI ≥30kg/m2 ; 

Severe obesity = BMI ≥40kg/m2

0%

10%

20%

30%

40%

50%

60%

Hypertension§ Coronary

Artery Disease

History of

Stroke

Diabetes Obesity Severe obesity Chronic kidney

disease

Asthma COPD

Prevalence (%)

COVID-NET Hospitalized Cases COVID-NET Catchment Area United States

https://medrxiv.org/cgi/content/short/2020.07.27.20161810v1 27
The magnitude of risk for COVID-19 associated hospitalization was greatest for adults 

with severe obesity, chronic kidney disease, and diabetes.

COPD: Chronic obstructive pulmonary disease

Obesity=BMI ≥30kg/m2 ; Severe obesity = BMI ≥40kg/m2

*Each underlying medical condition is in a separate model, adjusted for age, sex, race/ethnicity

4.4

4.0

3.2

2.9

2.8

1.4

1.3

0.9

0.9

-1 0 1 2 3 4 5 6 7

Adjusted Rate Ratios and 95% Confidence Intervals

Severe obesity

Chronic kidney disease

Diabetes

Obesity

Hypertension 

Asthma

Coronary Artery Disease

History of Stroke

COPD

28
The magnitude of risk for COVID-19 associated hospitalization was greatest for adults 

aged 65 years or older for all underlying medical conditions

Hypertension

Coronary 

Artery 

Disease

History 

of Stroke Diabetes Obesity 

Severe 

Obesity 

Chronic 

Kidney 

Disease 

Asthma COPD 

Age 65+ 

vs. 18-44 years 

2.2 

(1.7, 2.7)

3.7 

(2.9, 4.6)

3.8 

(3.1, 4.7)

2.5 

(1.9, 3.4)

4.5 

(3.4, 5.9)

4.6 

(3.6, 5.9)

3.4 

(2.7, 4.2)

3.8 

(3.1, 4.6)

3.8 

(3.0, 4.8)

Age 45-64 

vs. 18-44 years

1.6 

(1.3, 1.9)

2.3 

(1.9, 2.9)

2.4 

(2.0, 2.9)

1.9

(1.4, 2.4)

2.5 

(2.0, 3.3)

2.7 

(2.1, 3.4)

2.2 

(1.8, 2.7)

2.3 

(2.0, 2.8)

2.4 

(1.9, 2.9)

*Each underlying medical condition is modeled separately; models include the specific underlying medical condition of interest, age, sex, and race/ethnicity categories

COPD: Chronic obstructive pulmonary disease; Obesity=BMI ≥30kg/m2 ; Severe obesity = BMI ≥40kg/m2

https://medrxiv.org/cgi/content/short/2020.07.27.20161810v1

Adjusted Rate Ratios and 95% Confidence Intervals for Age and COVID-19-Associated Hospitalizations

29
Unadjusted and Adjusted* Rate Ratios for Number of Underlying Medical Conditions and COVID-19-Associated Hospitalization 

Unadjusted Rate Ratio (95%CI) Adjusted Rate Ratio* (95%CI)

Number of conditions†

1 2.8 (2.7, 3.1) 2.5 (2.1, 3.0)

2 5.6 (5.2, 6.1) 4.5 (3.7, 5.5)

3+ 7.2 (6.6, 7.9) 5.0 (3.9, 6.3)

Age 45-64 years‡ ----- 1.8 (1.5, 2.2)

Age 65+ years‡ ----- 2.6 (2.1, 3.1)

Male§ ----- 1.2 (1.1, 1.4)

Non-Hispanic black|| ----- 3.9 (3.3, 4.7)

Other race/ethnicity|| ----- 3.3 (2.8, 3.9)

CI: Confidence Interval; COVID-NET: Coronavirus Disease 2019-Associated Hospitalization Surveillance Network

*Model for number of conditions (variable) is adjusted for age, sex, and race/ethnicity

†Reference group is no underlying medical condition; Number of conditions is a sum of underlying medical conditions excluding hypertension; the most recent 

year of available BRFSS data for hypertension was 2017.

‡Reference group is 18-44 years 

§Reference group is female

||Reference group is non-Hispanic white 

The magnitude of risk for hospitalization increased with the number of underlying 

medical conditions, with the greatest risk among adults with 3 or more conditions.

30
COVID-NET/BRFSS Analysis Summary

 Accounting for age, race and ethnicity, and sex, higher hospitalization rates observed 

for community-dwelling adults with underlying medical conditions

– Adults with 3+ medical conditions had highest hospitalization risk

– Certain underlying medical conditions with higher risk 

• Severe obesity and chronic kidney disease associated with 4x hospitalization 

risk

• Diabetes, obesity, hypertension associated with approximately 3x 

hospitalization risk

 Accounting for the presence of an individual underlying medical condition, higher 

hospitalization rates were observed:

– Adults 65 years or older, 45-64 years (versus 18-44 years)

31
COVID-NET: Among 2,491 adults with COVID-19 associated hospitalization between March 1 and May 2, 

certain underlying medical conditions were independent risk factor for in-hospital death:

85+ years vs 18-39 years

75–84 years vs 18-39 years

65–74 years vs 18-39 years

50-64 years vs 18-39 years

Male

Immunosuppression

Renal disease

Chronic Lung Disease

Cardiovascular Disease

Neurologic disorder

Diabetes

10.98

7.67

5.77

3.11

1.3

1.39

1.33

1.31

1.28

1.25

1.19

-5 0 5 10 15 20

Adjusted Rate Ratios and 95% Confidence Intervals

*COVID-NET Surveillance; Final model adjusted for age, sex, race/ethnicity, smoker, hypertension, obesity, diabetes, chronic lung disease, cardiovascular disease, neurologic 

disease, renal disease, immunosuppression, hematologic disorders, and rheumatologic or autoimmune disease. Kim et al, 2020, https://academic.oup.com/cid/advancearticle/doi/10.1093/cid/ciaa1012/5872581 32
Multi-center U.S. cohort study: Among 2,215 adults with COVID-19 associated intensive care unit (ICU)-

admission between March 4 and April 4, 2020, certain underlying medical conditions were independent 

risk factor for death within 28 days of admission

Gupta et al, July 2020; https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2768602

*Modified from Gupta et al, 2020, JAMA Int Med. Multivariable risk model for 28-day death after ICU admission. Model adjusted for age, sex, race, other patient-level 

characteristics such as comorbidities, symptoms, and body mass index, and hospital-level characteristics such as number of ICU beds.

33
Supplementary U.S. case-based surveillance: Among a convenience sample of 10,647 COVID-19 deaths

that occurred during February 12-April 24 in 16 health jurisdictions, 76% of decedents had at least one 

underlying medical conditions, and majority of decedents of any age had multiple conditions

0 10 20 30 40 50 60 70 80 90

≥1 condition

≥2 conditions

≥3 conditions

Percentage of All Decedents (n=10,647)

Age group (yrs) <65 Age group (yrs) ≥65

Wortham et al, 2020: https://www.cdc.gov/mmwr/volumes/69/wr/mm6928e1.htm

Most common conditions:

Cardiovascular disease (60.9%)

Diabetes (39.5%)

Chronic Kidney Disease (20.8%)

Chronic Lung Disease (19.2%)

34
CDC has an ongoing, evidence-informed process to assess the risk 

for severe illness from COVID-19 for individuals with underlying 

medical conditions

 Comprehensive literature review ongoing

– Internal database to track reviewed articles (U.S. and global)

– Collaborating with SMEs across agency

– Standardized process for weekly updates of new peer-reviewed or inpress articles that may change our current understanding of the evidence 

 Monthly updates to published list of underlying medical conditions and 

associated evidence 

https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/evidence-table.html 35
Evidence Informed Process

 Two-tiered system based on level of evidence

– ARE associated with risk of severe illness from COVID-19  informed 

by STRONG evidence

– MIGHT BE associated with risk of severe illness from COVID-19 

informed by MIXED or LIMITED evidence

 Strongest evidence: consistent evidence from multiple small studies or a 

strong association from a large study

 Mixed evidence: multiple studies that reached different conclusions

 Limited evidence: consistent evidence from a small number of studies

https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/evidence-table.html 36
People with the following conditions ARE at increased 

risk for severe illness from COVID-19 

 Cancer

 Chronic kidney disease

 Chronic obstructive pulmonary disease

 Immunocompromised state from solid organ transplant

 Obesity (Body Mass Index of 30 or greater)

 Serious heart conditions (heart failure, coronary artery disease or 

cardiomyopathies)

 Sickle cell disease

 Type 2 diabetes mellitus

https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-with-medicalconditions.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fcoronavirus%2

F2019-ncov%2Fneed-extra-precautions%2Fgroups-at-higher-risk.html 37
People with the following conditions MIGHT BE at increased risk 

for severe illness from COVID-19 

 Asthma (moderate-to-severe)

 Cerebrovascular disease

 Hypertension

 Immunocompromised state from blood or BMT, immune deficiencies, HIV, steroid use, 

or other immunomodulators

 Neurologic conditions

 Liver disease

 Pregnancy

 Pulmonary fibrosis

 Smoking

 Thalassemia

 Type 1 diabetes mellitus

https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-with-medicalconditions.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fcoronavirus%2F2019-

ncov%2Fneed-extra-precautions%2Fgroups-at-higher-risk.html 38
Nationally, 41% of U.S. adults have at least one underlying medical 

condition that puts them at higher risk for severe illness from COVID-19 

 By county, the prevalence varies

from almost one in four to as 

many as two-thirds of adults 

having at least one underlying 

medical condition.

 In half of U.S. counties almost half

of adults are estimated to have an 

underlying medical condition.

Razzaghi et al, 2020: https://www.cdc.gov/mmwr/volumes/69/wr/mm6929a1.htm?s_cid=mm6929a1_w

Figure. Model-based estimates of U.S. number of adults aged >=18 years with any selected underlying 

medical condition,* by county—United States, 2018. Modified from MMWR reference

*Selected underlying conditions include chronic obstructive pulmonary disease, emphysema, or chronic 

bronchitis; heart disease (angina or coronary heart disease, heart attack, or myocardial infarction); 

diabetes; chronic kidney disease; or obesity (body mass index >=30 km/m2)

39
Summary
Summary

 As of August 23, over 5.6 million cases of COVID-19 diagnosed and over 173,000 

COVID-19-associated deaths reported in the United States 

 Older adults aged 65 years or older have the highest risk of severe COVID-19 disease

– Risk increases with increasing age

 Adults with underlying medical conditions are at increased risk for severe COVID-19

– Obesity, diabetes, and cardiovascular disease are common conditions observed 

across data sources

– Multi-morbidity increases risk of severe COVID-19 disease

 Surveillance/projects ongoing to continue to monitor COVID-19-associated 

hospitalizations and deaths and identify persons at higher risk for severe COVID-19 

disease

41
For more information, contact CDC

1-800-CDC-INFO (232-4636)

TTY: 1-888-232-6348 www.cdc.gov

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

official position of the Centers for Disease Control and Prevention.

Acknowledgements:

• COVID-NET Hospitalization Surveillance Team

• Community Interventions & Critical Populations Task Force
Coronavirus Disease 2019-Associated 

Hospitalization Surveillance (COVID-NET)

 All age population-based surveillance system of laboratory-confirmed 

COVID-19-associated hospitalizations

– Positive SARS-CoV-2 test no more than 14 days before admission or 

during hospitalization

– Be a resident of the pre-identified surveillance catchment area

– Be admitted to a hospital where residents of the surveillance 

catchment area receive care

 Medical chart abstractions using a standard case report form 

– Patient demographics and underlying medical conditions

43
Behavioral Risk Factor Surveillance System (BRFSS) 

Overview 

 Cross sectional survey that collects data on health-related risk behaviors, chronic 

health conditions, and use of preventative services among adults (≥ 18 years).

 BRFSS collects data annually in all 50 states, D.C., and three U.S. territories.

 More than 400,000 adult interviews each year.

 Standardized methodology for weighting data to be representative of population.

https://www.cdc.gov/brfss/index.html 44
20,046 adults with laboratory-confirmed 

COVID-19-associated hospitalizations as of 

June 23, 2020 from 70 counties in 12 

states* participating in COVID-NET

Excluded: 2,258 non-community dwelling adults 

and 12,073 adults with data yet to be 

abstracted†

Eligible adults

N= 5,715

299 excluded due to missing data on all the 

underlying medical conditions 

Included in analysis

N=5,416

*California, Colorado, Connecticut, Georgia, Maryland, Michigan, Minnesota, New Mexico, New York, Oregon, Tennessee, and Utah. 

†Additional data beyond the minimum required data elements may be subject to a time lag for submission to CDC. 45
Demographic Characteristics of Adults with COVID-19-

Associated Hospitalizations in Analytic Sample (N=5,416)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Sex Age Group Race/Ethnicity*

Male

(53%)

Female

(47%)

18-44 years

(30%)

46-64 years

(40%)

65+ years

(31%)

Non-Hispanic 

White

(34%)

Non-Hispanic Black 

(32%)

Other (34%)

*197 hospitalizations missing race/ethnicity information 46
Defining Underlying Medical Conditions

BRFSS = Behavioral Risk Factor Surveillance System; COVID-NET: Coronavirus Disease 2019-Associated Hospitalization Surveillance 

Underlying medical 

condition

COVID-NET

(medical chart abstraction)

BRFSS (self-report)

Has a doctor, nurse, or other health professional ever told you that 

you had any of the following?

Hypertension Hypertension Yes to ever told you have high blood pressure and are currently taking 

medication for high blood pressure (2017 BRFSS)

Coronary Artery Disease History of myocardial infarction, 

coronary artery disease, coronary 

artery bypass graphing

Yes to ever told you had a heart attack also called myocardial 

infarction? Or Yes to ever told you had angina or coronary heart 

disease?

Stroke Stroke Yes to ever told you had a stroke

Diabetes Diabetes Yes to ever told you have diabetes?

Obesity BMI≥30kg/m2; denominator is 

everyone in sample

Obesity defined as BMI≥30kg/m2 based on self-reported height and 

weight.

Severe Obesity BMI≥40kg/m2; denominator is 

everyone in sample

Severe obesity defined as BMI≥40kg/m2 based on self-reported height 

and weight.

Chronic Kidney Disease Chronic Kidney Disease Yes to ever told kidney disease

Asthma Asthma Yes to do you still have asthma

Chronic obstructive 

pulmonary disease (COPD)

COPD Yes ever told you have COPD, emphysema, or chronic bronchitis

Number of conditions Sum of any of the above underlying 

medical condition except for 

hypertension; categorized (0,1,2,3+)

Sum of any of the above underlying medical condition except for 

hypertension (because hypertension not available in 2018 BRFSS data); 

categorized (0,1,2,3+) 47
Adjusted Rate Ratios (aRR) and 95% Confidence Intervals for Race/Ethnicity 

and COVID-19-Associated Hospitalizations by Underlying Medical Condition*

Hypertension

Coronary 

Artery 

Disease

History 

of Stroke Diabetes Obesity 

Severe 

Obesity 

Chronic 

Kidney 

Disease 

Asthma COPD 

Non-Hispanic 

black vs. nonHispanic white

4.0 

(3.3, 4.8)

4.7

(3.8, 5.8)

4.7 

(3.9, 5.7)

4.0 

(3.1, 5.2)

4.4 

(3.4, 5.7)

4.7 

(3.8, 5.9)

4.5 

(3.7, 5.6)

4.7 

(3.9, 5.6)

4.7 

(3.8, 5.9)

Other 

race/ethnicity 

vs. nonHispanic white 

3.5 

(2.9, 4.2)

3.3 

(2.7, 4.0)

3.3 

(2.7, 4.0)

3.0 

(2.3, 3.9)

3.5 

(2.8, 4.5)

3.5 

(2.8, 4.3)

3.3 

(2.7, 4.1)

3.2 

(2.7, 4.0)

3.3 

(2.7, 4.1)

COPD: Chronic obstructive pulmonary disease

*Each underlying medical condition is modeled separately; models include the specific underlying medical condition of interest, age, sex, and race/ethnicity categories

https://medrxiv.org/cgi/content/short/2020.07.27.20161810v1 48
Adjusted Rate Ratios (aRR) and 95% Confidence Intervals for Sex and COVID19-Associated Hospitalizations by Underlying Medical Condition*

Hypertension

Coronary 

Artery 

Disease

History of 

Stroke Diabetes Obesity 

Severe 

Obesity 

Chronic 

Kidney 

Disease 

Asthma COPD 

Male 

vs. females

1.2 

(1.1, 1.4)

1.2 

(1.03, 1.4)

1.2 

(1.1, 1.4)

1.2 

(0.98, 1.5)

1.4 

(1.1, 1.7)

1.4 

(1.1, 1.7)

1.2 

(1.02, 1.4)

1.2 

(1.1, 1.5)

1.2 

(1.03, 1.5)

COPD: Chronic obstructive pulmonary disease

*Each underlying medical condition is modeled separately; models include the specific underlying medical condition of interest, age, sex, and race/ethnicity categories

https://medrxiv.org/cgi/content/short/2020.07.27.20161810v1 49
50
Selected underlying medical conditions contributing to deaths 

involving COVID-19 from U.S. death certificate data (n=153,504)

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000

Obesity

Alzheimer disease

Other diseases of the respiratory system

Malignant neoplasms

Cerebrovascular diseases

Other diseases of the circulatory system

Heart failure

Renal failure

Chronic lower respiratory diseases

Ischemic heart disease

Vascular and unspecified dementia

Diabetes

Hypertensive diseases

Provisional death counts are based on death certificate data received and coded by the National Center for Health Statistics and do not represent all deaths that 

occurred in that period, data as of 8/15/20: https://www.cdc.gov/nchs/nvss/vsrr/covid_weekly/index.htm#Comorbidities 51
Recent global meta-analysis of underlying 

medical conditions and severe COVID-19 

disease showed similar results to U.S. studies. 

Most prevalent conditions, unadjusted for age: 

- Obesity

- Hypertension

- Diabetes

- Cardiovascular Disease

Fig. Most prevalent underlying medical conditions

Modified from Zhou et al, July 2020: https://www.sciencedirect.com/science/article/pii/S120197122030572552

54