RTI Project Number

0208665.001

Influenza Vaccine Demand: The Chicken And The Egg

Issue Brief

October 2005

Prepared for

Amy Nevel, MPH

Senior Public Health Policy Analyst

Office of Science and Data Policy

Assistant Secretary for Planning and Evaluation

Department of Health and Human Services

Mail Stop 445F

200 Independence Ave., SW

Washington DC 20201

Prepared by

Christine Layton, PhD, MPH

Tara Robinson, BA

Amanda Honeycutt, PhD

RTI International\*

Health, Social, and Economics Research

Research Triangle Park, NC 27709

\*RTI International is a trade name of Research Triangle Institute.

Contents

Page

[1. Introduction 2](#introduction)

[1.1 Key Issues 2](#key-issues)

[1.2 The Purpose of This Issue Brief
2](#the-purpose-of-this-issue-brief)

[2. The Critical Nature of Demand in Influenza Vaccine Supply
2](#the-critical-nature-of-demand-in-influenza-vaccine-supply)

[2.2 Factors that Affect Demand 2](#factors-that-affect-demand)

[2.3 Approaches to Increase Demand 2](#approaches-to-increase-demand)

[3. Roles for Stakeholders in Increasing Demand
2](#roles-for-stakeholders-in-increasing-demand)

[3.1 Federal Government 2](#federal-government)

[3.2 Vaccine Manufactures 2](#vaccine-manufactures)

[3.3 State and Local Governments 2](#state-and-local-governments)

[3.4 Wholesalers 2](#wholesalers)

[3.5 Professional Organizations 2](#professional-organizations)

[3.6 Health Insurance Companies 2](#health-insurance-companies)

[3.7 Private Health Care Providers 2](#private-health-care-providers)

[4. Summary and Conclusion 2](#summary-and-conclusion)

[References 2](#references)

List of Figures

Number Page

[1. Influenza Vaccine Supply and Demand Interrelationship
2](#__RefHeading___Toc118275604)

[2. Price Elasticity of Demand for the Influenza Vaccine
2](#__RefHeading___Toc118275605)

[3. Site of Vaccination of Persons 65 Years of Age or Older
2](#__RefHeading___Toc118275606)

List of Tables

Number Page

[1. Changes in ACIP Influenza Vaccination Target Groups: 1999--2000
through 2005--2006 Influenza Seasons 2](#__RefHeading___Toc118275629)

[2. Influenza Vaccination Rates by Race 2](#__RefHeading___Toc118275630)

This issue brief is one of five produced for the Assistant Secretary for
Planning and Evaluation (ASPE) by RTI International. The contents of
these briefs is based upon research involving a review of literature
including peer-reviewed journals, media reports, and other
non-referenced sources including those identified using the World Wide
Web search engine Google as well as confidential interviews with 30 key
informants representing influenza vaccine manufacturers, wholesalers,
community immunizers, state and local public health officials, and other
experts. The other briefs in the series are

-   *Influenza Vaccine Economics*

-   *Influenza Vaccine: Who Buys It and Who Sells It*

-   *Influenza Vaccine Manufacturing*

-   *Influenza Vaccine Overview: Summary and Assessment.*

This issue brief was written by Christine Layton, PhD, MPH, Tara
Robinson, BA, and Amanda Honeycutt, PhD.

# INFLUENZA VACCINE DEMAND: THE CHICKEN AND THE EGG

# Issue Brief

## 1. Introduction

### 1.1 Key Issues

The demand for influenza vaccine is a critical component in its
availability. Unlike childhood vaccines whose demand is relatively
simple for vaccine manufacturers to predict, influenza vaccine demand is
more uncertain. As one expert explained,

> *... we don't have ... signals in society that tell us what the size
> of the market is going to be \[for influenza vaccine\]. We have that
> for all of the pediatric vaccines simply because demographers can tell
> us what the birth cohort is going to be ... Anybody who knows what
> that birth cohort is 5 years from now ... knows the number of doses of
> vaccine you're going to have to give ... We don't have that kind of
> signal for the demand of flu \[vaccine\].*

Meanwhile, because influenza vaccine is a seasonal product,[^1] vaccine
manufacturers are reluctant to produce more influenza vaccine than they
believe they can sell in a given season.

> *... flu vaccine ... changes every year and you throw out stock that
> \[is unused at the end of a season\]. So that's why people try to
> manufacture just what they think they can sell every year. You can't
> sell it next year. If you \[are\] making measles vaccine you can
> stockpile. You can't do that for flu vaccine. So that's behind the
> idea of demand driving supply.*

Although influenza vaccine demand and supply are intricately linked
(Figure 1), it appears that demand is the "tail that wags the dog."
However, regardless of whether demand or supply is more important, the
reality is that, to protect the public's health---especially those at
increased risk for complications from influenza---demand for influenza
vaccine is key to increasing the overall supply.

Annually, influenza causes an average of 36,000 deaths (Thompson et al.,
2003) and 226,000 hospitalizations (Thompson et al., 2004). Despite such
sobering statistics, immunization rates for those at high risk for
complications and with health insurance for the immunization

[]{#__RefHeading___Toc118275604 .anchor}**Figure 1**. Influenza Vaccine
Supply and Demand Interrelationship

![](media/image1.wmf){width="2.448611111111111in" height="1.3125in"}

(e.g., Medicare recipients)---a group many would think the most likely
to be immunized---are not immunized at levels that meet objectives such
as *Healthy People 2010* (Centers for Disease Control and Prevention
\[CDC\], 2000).[^2]

Many different factors and stakeholders affect demand for influenza
vaccine. One expert said, " ... a potpourri of administrative
\[issues\], financial incentives, accountability using the regulatory
things such as contracts ... " will affect demand. As we explain in
detail later in this issue brief, factors that can affect influenza
vaccine demand include

+-----------------------------------+----------------------------------+
| -   price of vaccination          | -   demographics (race,          |
|                                   |     ethnicity, socioeconomic     |
| -   convenience                   |     status)                      |
|                                   |                                  |
| -   knowledge of influenza's      | -   severity of previous year's  |
|     impact                        |     influenza season             |
|                                   |                                  |
| -   severity and timing of        | -   perception of need           |
|     influenza season              |                                  |
|                                   | -   provider's recommendation    |
+-----------------------------------+----------------------------------+

A variety of stakeholders are also involved. These stakeholders work
independently and together to affect demand for influenza vaccine. The
stakeholders that are involved in increasing influenza vaccine demand
include

+-----------------------------------+-----------------------------------+
| -   federal government            | -   health insurance companies    |
|                                   |                                   |
| -   state and local governments   | -   vaccine industry              |
|                                   |     (manufacturers, distributors) |
| -   academia                      |                                   |
|                                   | -   wholesalers                   |
| -   health care providers         |                                   |
|                                   | -   professional societies        |
| -   community immunizers          |                                   |
|                                   | -   consumers                     |
| -   advocacy organizations        |                                   |
+-----------------------------------+-----------------------------------+

### 1.2 The Purpose of This Issue Brief

This brief reviews the issues associated with influenza vaccine demand,
including the relationship between influenza vaccine demand and supply
and how demand may be seen as the linchpin in the influenza vaccination
system. Factors that affect demand are reviewed, as are stakeholders'
roles and responsibilities in increasing demand for influenza vaccine.

## 2. The Critical Nature of Demand in Influenza Vaccine Supply

Due to a myriad of factors detailed in the companion brief, *Influenza
Vaccine Manufacturing*, influenza vaccine manufacturers produce what
they predict they can sell in a given influenza season. Influenza
vaccine is unlike other vaccines or pharmaceuticals because, among other
reasons, its functional shelf-life is only a few months (typically,
October through December in a given year). Because unused influenza
vaccine generally cannot be returned to the manufacturer (a change that
has taken place over the past few years), the health care providers or
wholesalers that have vaccine at the end of the influenza season may
suffer a financial loss. Given the negative impact of such a situation,
wholesalers, purchasers, and health care providers are reluctant to
order more than they think will be used in a given season. As a result,
an unexpected increase in demand for influenza vaccine by the public can
cause shortages (perceived or actual).

### 2.2 Factors that Affect Demand

Various determinants and conditions cultivate high or low levels of
demand for influenza vaccine. The United States has seen volatile
fluctuations in demand over the past decade; however, the market
continues to expand and demand continues to increase. A primary driver
of influenza vaccine demand is annual recommendations made by the
Centers for Disease Control and Prevention (CDC) regarding who should
receive the vaccine. The Advisory Committee on Immunization Practices
(ACIP) is a 15-member panel of immunization experts in medicine,
immunology, and public health that advises CDC and develops written
recommendations for routine vaccine administration, including influenza
vaccine. The CDC director has the discretion to adopt or reject the ACIP
recommendations. ACIP recommendations regarding who ought to receive
influenza vaccination have broadened over the past decade. For many
years, the initial recommendation was for those 65 years of age or older
and those with chronic health conditions, who were more likely to
develop complications from influenza, to receive an annual influenza
immunization. As shown in Table 1, ACIP has broadened its
recommendations in recent years to include other target groups.[^3]

[]{#__RefHeading___Toc118275629 .anchor}Table 1. Changes in ACIP
Influenza Vaccination Target Groups: 1999--2000 through 2005--2006
Influenza Seasons

  --------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ----------------
  **Target        **1999--2000**   **2000--2001**   **2001--2002**   **2002--2003**   **2003--2004**   **2004--2005**   **2005--2006**
  Group**                                                                                                               

  ≥ 65 years of   X                X                X                X                X                X                X
  age                                                                                                                   

  Chronically ill X                X                X                X                X                X                X

  Pregnant^a^                      X                X                X                X                X                X

  ≥ 50 years of                    X                X                X                X                X                X
  age                                                                                                                   

  Household       X                X                X                X                X                X                X
  contacts of                                                                                                           
  high-priority                                                                                                         
  persons                                                                                                               

  Health care                      X                X                X                X                X                X
  workers                                                                                                               

  6 to 23 months                                                                                       X                X
  of age                                                                                                                
  --------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ----------------

^a^ Those who will be in the second or third trimester of pregnancy
during influenza season. As of 2004, annual vaccination was recommended
for all pregnant women, if they were pregnant during influenza season.

Sources: ACIP, 1999; ACIP, 2000; ACIP, 2001; Bridges, Fukuda, Uyeki,
Cox, & Singleton, 2002; Bridges et al., 2003; CDC, 2005b; CDC, 2005c;
Harper, Fukuda, Uyeki, Cox, & Bridges, 2004; Harper, Fukuda, Uyeki, Cox,
& Bridges, 2005.

In 2000, ACIP broadened its recommendations to include pregnant women
who would be in the second or third trimester during influenza season,
health care workers, and those 50 years of age or older (Advisory
Committee on Immunization Practices \[ACIP\], 2000). In 2004, ACIP
further broadened its recommendation to include children 6 through 23
months of age (ACIP, 2004). CDC estimates that the total number of those
currently included in all the target groups is 183.3 million (CDC,
2005b).

As is true for so many other phenomena, no one factor fully predicts
demand. In addition to an expansion in the market and increase in
demand, price elasticity, convenience, knowledge of influenza's impact,
severity and timing of the influenza season, demographics, severity of
the previous year's season, provider's recommendation, and perception of
need are additional important factors that affect demand. The rest of
this section addresses the issues that have influenced demand in
previous seasons.

#### 2.2.1 Price

The field of economics tells us that price is often a key to predicting
quantity demanded. Understanding the impact of influenza vaccine prices
on demand for the vaccine requires an understanding of other factors
that affect demand for the vaccine (see Figure 2). First, the risk
associated with influenza is not the same for all persons. For most
people, influenza means a week in bed feeling miserable; for some it is
life threatening. For those at high risk of complications, influenza
vaccine is perceived as more necessary. Therefore, we would expect a
willingness to pay a higher price. The second factor is that influenza
vaccine is a covered benefit for most of those who are at highest risk,
notably Medicare beneficiaries 65 years of age or older. An increase in
cost would not affect these persons. Such a situation is described in
economic terms as less elastic: if the price increases, manufacturers
would see a relatively small decrease in the number of doses demanded,
simply because the price increases would not be passed along to Medicare
beneficiaries.

[]{#__RefHeading___Toc118275605 .anchor}Figure 2. Price Elasticity of
Demand for the Influenza Vaccine

![](media/image2.wmf){width="4.820833333333334in"
height="3.248611111111111in"}

With elastic demand (D^elastic^), a small increase in price (P~1~ to
P~3~) will cause a large reduction in quantity demanded (Q~1~ to Q~3~).
With inelastic demand (D^inelastic^), a large increase in price (P~1~to
P~2~) will cause only a small decrease in quantity demanded (Q~1~ to
Q~2~).

Alternatively, those at lesser risk have more elastic demand, meaning
that if price were to increase, these consumers would demand
significantly less influenza vaccine. A recent article in the journal
*Health Affairs* suggests that the price in the influenza vaccine market
is set by the "marginal consumer," which means that those with greater
price elasticity of demand will ultimately set the price. This marginal
consumer is the healthy young person who does not perceive the influenza
vaccine as a necessity (Pauly, 2005). However, in our research, we did
not find any evidence to confirm this assertion. Our interviews with
influenza vaccine manufacturers and other experts indicated that the way
in which influenza vaccine prices are set is proprietary and may or may
not reflect economic theories regarding pricing.

We know people do respond to pricing, but not how much. People who
believe that getting an influenza vaccine is important may exhibit
little response to changes in price. This may be true for Medicare
beneficiaries or others in priority groups for influenza vaccination.
Those who are not in the priority groups---notably healthy children and
adults---may be more responsive to price; \$10 vs. \$50 could be an
important price difference for those without health insurance coverage.
For these price-sensitive subgroups, a small price increase would reduce
their demand for vaccine.

Responsiveness to vaccine prices may also vary across different income
groups. Among poor and uninsured people, price is a significant barrier.
Prices for the influenza vaccine may already be set high enough to
discourage them from purchasing the vaccine. A recent review article
reported that when vaccines are provided for free, coverage will
increase by 10 percent to 30 percent among certain groups (Helms et al.,
2005). However, it should be noted that for those 65 years of age or
older with Medicare, influenza vaccination rates remain below goals
established by *Healthy People 2010* (CDC, 2000).

In addition to the price of influenza vaccine itself is the cost of
administration. Although the cost of one dose of influenza vaccine may
be as little as \$10, this is not generally the price paid by the person
receiving the vaccine.

For-profit community immunizers with whom we spoke explained that they
did not know the price at which consumers would opt not to be
vaccinated. One community immunizer explained that it would set the
retail price for influenza immunization at \$25 for the 2005--2006
season. "I think people will still see a value in it. I'm hoping. But I
don't know where that point \[where people would not get immunized
because the cost is too high\] is. It could be \$24, and we'll be in
trouble."

#### 2.2.2 Convenience

Convenience is a necessary determinant of vaccination decisions, and the
level of effort a consumer must put forth to get vaccinated is a key
determinant in demand for influenza vaccine. Evidence suggests that the
more convenient the vaccination process is, the more likely an
individual will be to get vaccinated. Less evidence suggests that people
perceive influenza vaccine as hard to find---except during seasons in
which there is a vaccine shortage. However, a person's *perception* of a
shortage will also affect demand. If a patient perceives a large
shortage, usually due to delays in delivery, the patient may make an
early decision in October or November---the height of seasonal demand.
If the vaccine is not available at that time, the patient will likely
not be vaccinated (Nowalk, 2005). Timing will be discussed in following
sections.

One's perception of convenience appears to depend on where influenza
immunizations are provided. In a study conducted by researchers at the
University of Pittsburgh in 2005, interviewers surveyed parents with
children 6 to 23 months of age about their perceptions of the influenza
vaccine. In this study, 83 percent of parents whose children received
influenza vaccine said that it was easy to go to the child's doctor to
get the vaccine; 79 percent of parents of unvaccinated children also
said it was easy (Nowalk, 2005). Notice that these perceptions are among
parents of young children who have frequent well-child visits.[^4]
Preventive health visits are much less frequent among adults. In fact,
most adults do not have annual exams, but rather visit their physician
only if they have acute or chronic illness. Although women do tend to
comply with yearly visits to the gynecologist, vaccination in the
gynecologist's office is not common (Helms et al., 2005).

Various attempts and interventions have been explored to increase
vaccination levels. Organizational change, free vaccination, and gift
incentives have been identified as effective measures to increase
vaccination among adults (Briss et al., 2000). Some successful examples
range from vaccination in nontraditional settings to provider-based
approaches. Places such as work sites, grocery stores, pharmacies,
shopping malls, and detention centers can effectively increase
vaccination among groups that do not usually receive annual vaccination
(Helms et al., 2005). Figure 3 illustrates how immunization in
nontraditional sites is becoming more common.

#### 2.2.3 Knowledge of Influenza's Risk to Health

The public lacks an accurate understanding of how serious influenza can
be. Although for most people infected, the illness results in feeling
miserable for a few days; for some it can be life threatening. In a
study by researchers at Harvard University, survey respondents were
offered a multiple choice question about the number of deaths associated
with influenza annually (DesRoches, Blendon, & Benson, 2005). Given five
possible options, only four percent selected the correct answer. More
than half (63 percent) underestimated the number, and only 8 percent

[]{#__RefHeading___Toc118275606 .anchor}Figure 3. Site of Vaccination of
Persons 65 Years of Age or Older

![](media/image3.wmf){width="6.497916666666667in"
height="4.090972222222222in"}

Source: Compiled from Behavioral Risk Factor Surveillance System survey
data (CDC, 1999, 2002, 2003).

overestimated the number. This may lead one to believe that if the
public had a better sense of the risks associated with influenza---not
only to themselves but to the public as a whole, demand for influenza
vaccine would increase. However, the same study asked respondents to
identify the means that are "very effective at preventing you from
getting sick with the flu." Fewer than half (44 percent) noted influenza
vaccination. Respondents reported the belief that hand washing, avoiding
those with influenza, and avoiding touching one's eyes, nose, or mouth
were more effective at preventing influenza (72, 64, and 52 percent
respectively). Key informants echoed this concern about the public's
understanding of influenza and immunization:

> *There has to be a better understanding, just in terms of the vaccine
> and what it can do. Last year a lot of people didn't get vaccinated
> and we didn't have a bad flu year so people are saying, 'So why should
> I get vaccinated?'*

Many interviewees mentioned the idea of public education to promote
awareness of influenza's risk to the public health and the efficacy of
influenza vaccine. As one influenza vaccine manufacturer said,

> *\[We need\] some sort of mass education, which would include
> CDC-based or state health department-based advertising---"go get your
> flu vaccine," "protect yourself from a serious infectious disease that
> could kill you." Not too polite words. People need to be hit over the
> head.*

#### 2.2.4 Severity and Timing of the Influenza Season

The severity and timing of the influenza season can also affect the
demand for influenza vaccine. Years in which influenza is perceived to
be particularly severe or occurs early (around November or December) are
more likely to see increases in vaccine demand. One recent example
occurred during the 2003--2004 influenza season---most notably in
Colorado. The worries started in Colorado when the influenza season
began early and deaths were reported among children, suggesting an
unusually virulent illness. In early November, the first reports of high
absenteeism in schools were made available. By the end of the month,
Colorado's vaccine locator Web site had 2.3 million hits. In December,
the Web site received 2.9 million hits. In January, the demand began to
diminish rapidly (Gershman, Smith, & Trefren, 2004). A health official
explained,

> *... 2003--2004 ... was the first year we used all of the
> \[influenza\] vaccine. We never \[had\] used all of the influenza
> vaccine supply until that year, and people think we had a shortage of
> vaccine. But no, we actually used the vaccine. If you have a severe
> flu season, you're going to increase demand for sure.*

CDC ultimately described the 2003--2004 season as "moderately severe"
(Mitka, 2004). By May 31, 2004, a total of 152 influenza-associated
deaths occurred among those 18 years of age or younger (CDC, 2005a).
Whether this number represents a substantially higher rate than in
previous influenza seasons is difficult to ascertain because no similar
data were collected previously.[^5] However, one model estimated that
between 1990 and 1999, approximately 92 influenza-related pediatric
deaths occurred among children younger than 5 years of age (Thompson et
al., 2003). Given these data, it does not appear that the 2003--2004
influenza season had more influenza-associated pediatric deaths than
usual.

In seasons when influenza infections occur late, demand for vaccine
tends to be low. Once potential vaccinees have made it far enough
through the season, they are unlikely to get vaccinated, often assuming
that if they have made it past January, the risk of infection is too low
to warrant the effort to be immunized. However, the public is not
entirely to blame for these late-season decisions. Health care providers
also make similar assumptions. A recent article described why people do
not receive influenza vaccines in December and January (Fishbein et al.,
2005). Evidence suggests that providers cease recommendations and
attempts to get their patients vaccinated at this point. With health
care providers as key demand inducers, this could potentially lead to
even lower vaccination levels. After December and January, the number of
missed opportunities to vaccinate patients who are already in the office
is high (Fishbein et al., 2005).

#### 2.2.5 Demographics

An additional factor affecting demand for influenza vaccine is
demographics---most notably race. Among all persons 65 years of age or
older, and those living below the poverty level, whites are more likely
than blacks or Hispanics to have received an influenza vaccination (CDC,
2003). (See Table 2.) Hebert, Frick, Kane, & McBean (2005) report that
the explanation for these disparities is that whites are more likely to
initiate visits for influenza immunization. Such data indicate the need
to address these racial disparities. Data from Veterans Administration
clinics suggest that disparities can be eliminated by health care
providers recommending influenza immunizations to their patients more
directly (Zimmerman et al., 2003).

[]{#__RefHeading___Toc118275630 .anchor}Table 2. Influenza Vaccination
Rates by Race

  ---------------------------- -------------- -------------- --------------
                               **White**      **Black**      **Hispanic**

  65 years of age or older     66%            48%            54%

  Below poverty level          57%            49%            48%
  ---------------------------- -------------- -------------- --------------

Source: National Health Interview Survey 2000 and 2001 combined (as
cited in CDC, 2003)

#### 2.2.6 Severity of Previous Years' Influenza Season

Manufacturers and consumers alike assess the risks and benefits of
production or consumption, which is usually decided before the influenza
season begins. Just as manufacturers are making production decisions
before the upcoming influenza season, potential vacinees are making
similar consumption decisions based on their perception of the previous
season. For example, if an individual perceived the previous influenza
season as severe either because they or someone they knew got sick, or
due to media attention, this individual is more likely to get vaccinated
than in the absence of these events. The individual will interpret these
events as risk and weigh the cost and benefit of the vaccine. Especially
if perceived risks are high, the benefits will far outweigh the costs
involved in getting the vaccine. However, unlike manufactures, potential
vacinees may reevaluate their perception of risk during a given
influenza season and conclude that the risk is higher than they
initially thought. Unfortunately, when such persons change their mind,
they may do so too late in the season to obtain influenza vaccination.

From the manufacturer's perspective, once a season has finished, the
company will begin to predict demand for the following season. Demand
for the previous season's vaccine is very important in determining
production levels for the upcoming season. For example, ignoring
Chiron's unanticipated absence from the 2004--2005 influenza vaccine
makers, the United States anticipated approximately 100 million doses
due to the apparent increase in demand in the 2003--2004 season. On the
contrary, Charatan (2004, p. 8) said that, "The \[2003--2004\] vaccine
shortage was the result of poor demand in previous years, leading to
overproduction and subsequent loss to the manufacturers. Only 83 million
doses of the vaccine were available, whereas an estimated 185 million
doses were needed."

Ultimately, it is the previous year's demand that helps predict the next
year's demand. One health official put it bluntly,

> *I think if we have a severe flu season every year, that's a great way
> to increase demand because it's tangible. People can see the effects
> of influenza and actually take action on that, whereas if there's a
> mild flu season like the past year the demand isn't so high so it's
> not such a problem.*

As this description does not reflect the nature of the situation, what
actually occurs are fluctuations in demand that are frustrating for
advocates of influenza vaccination and disruptive for vaccine
production. One interviewee summarized the true situation:

> *The concern I have for this \[influenza vaccination\] industry is
> what I see happening. We have a lesson from just a couple years ago
> \[2000--2001\]---the last time we had a shortage, actually they called
> it a delay---the following year was the problem. The problem was that
> the next year 20M doses went unused ... People are fighting a 50M-dose
> battle for 2005 already. People have to see that each year is
> different. It's very reactionary. And we're talking about state
> government, county officials, even the CDC. I think the CDC is getting
> smarter about this all the time. They say, "You see one flu season;
> you've seen one flu season." My biggest concern in the short term is
> that people are playing last year's game or fighting last year's
> battle when we really need to see what this year's battle is ...*

#### 2.2.7 Perception of Need

As explained earlier, the public has a poor understanding of the risks
associated with influenza and the potential benefits associated with
vaccination. Clearly, if the public perceived that they need influenza
vaccine, demand would rise. Although the public may understand that
those at increased risk for influenza should be vaccinated, exactly who
falls into what risk groups is poorly understood.

As part of the Medicare Current Beneficiary Survey (MCBS),[^6] Medicare
beneficiaries 65 years of age or older were asked to state their reason
for not getting an influenza shot for the influenza seasons between the
years 1997--2002. Overall, the most common reason for not being
vaccinated in the survey years was because respondents did not know the
vaccine was needed. The second most common reason was that respondents
believed that the vaccine itself could cause influenza (CDC, 2004).

This situation is exacerbated by what many have described as
inconsistent messaging from ACIP and CDC. As one public health expert
explained,

> *We definitely need to have consistent messages year to year. I
> realize that with the influenza vaccine supply situation, ... this is
> not always doable but in the past years we've lost a lot of healthy
> people who would normally get their flu shots because we've asked them
> to step aside so much that our coalition actually is concerned that
> we've lost those people and there goes our demand for the flu vaccine
> because there're less people demanding it because they've been told,
> "It's not really that important. We've got to get it to the high-risk
> people first." That's how the message comes across to the public.*

In addition to inconsistent messages regarding who should be
targeted---particularly when there is a shortage of vaccine---is the
public's misconceptions concerning the influenza vaccine itself. "We
don't get a good message out with influenza because people think that if
they get sick it's the vaccine. They don't realize it's a killed
vaccine." Many other people who become ill despite receiving an
influenza immunization believe that the vaccine was ineffective. Such
people do not understand that they may have an "influenza-like illness"
(i.e., an illness with symptoms similar to those associated with
influenza but not actually caused by the influenza virus) or that the
vaccine requires approximately 2 weeks to produce immunity (it is
possible to become infected with influenza between the time the vaccine
is administered and an adequate immune response is achieved). It is
likely that such misconceptions could be corrected and demand increased
by increasing and improving the information presented to the public.

> *When's the last time you saw an immunization message on Superbowl
> Sunday. If we had a public campaign we could forget ACIP
> recommendations. We create demand for \$200 tennis shoes, why not a
> vaccine that could save your life? It's nuts. We don't go prime time.
> You could circumvent the problem \[of public misunderstanding\] with a
> clear message to the public. You create demand that way. That's what
> we do with everything else. Look at Viagra! We don't do that with
> influenza vaccine.*

### 2.3 Approaches to Increase Demand

Increased demand for the influenza vaccine may help to limit or
eliminate shortages of the vaccine. If manufacturers expect the U.S.
demand for influenza vaccine to grow, particularly growth coupled with
less volatility in demand, they may feel less vulnerable to the risk of
profit losses associated with having to throw out excess vaccines.
Manufacturers may have less incentive to produce only the number of
doses they believe can be sold. Growing demand may also encourage
existing producers to expand production and may provide incentive for
new producers to enter the influenza vaccine market. Increasing the
number of influenza vaccine producers will limit the possibility of
shortages because the loss or delay of any one manufacturer's doses due
to production problems will have less impact on the overall supply of
the vaccine. In this section, we describe a number of approaches that
may work to increase the demand for influenza vaccine, and ultimately,
reduce shortages.

#### 2.3.1 National Adult Immunization Program

The creation of a national adult immunization program, which would
provide vaccines free of charge to specified populations through their
current provider, could serve to increase demand for the influenza
vaccine. Most proponents of a national adult immunization program have
suggested that it could operate much the way the Vaccines for Children
(VFC) program works. VFC was intended to provide vaccines to low-income,
underinsured children by giving enrolled providers free vaccines for
these eligible populations. A national adult immunization program
working in a similar way could help increase the demand for influenza
and other adult vaccines among low-income adults in target groups who
are not eligible for Medicare or other health insurance that includes
vaccine coverage. For example, low-income individuals between 50 and 64
years of age and adults of any age with chronic conditions such as
asthma, diabetes, heart disease, or chronic lung disease could benefit
from such a program. Because we are discussing a number of similar
strategies for increasing demand for the influenza vaccine, it is
important to note that a national adult immunization program could help
raise demand for the influenza vaccine primarily by creating incentives
for health care providers to offer and administer vaccines to their
adult patients. The primary incentive of such an approach (at least for
influenza immunization) would be to remove the financial risk associated
with purchasing influenza vaccine.

#### 2.3.2 Universal Recommendations

A universal recommendation would recommend that all persons, regardless
of age or presence of underlying health conditions, receive an annual
influenza vaccination. Such a recommendation could help increase demand
for the influenza vaccine both through its impact on demand in the
general population and through its impact on providers' perceptions of
the importance of influenza vaccination for even healthy adults and
children. For example, a universal recommendation could cause a healthy
person to consider getting the vaccine when he or she otherwise would
not have. Additionally, because the perceptions and actions of health
care providers may also be influenced by a universal recommendation for
influenza vaccination, health care providers could be more likely to
purchase vaccine for their patients and to encourage vaccination of all
patients during the October through March period. Finally, the policies
of health insurers are also often influenced directly and indirectly by
ACIP recommendations. Employers who sponsor insurance (either through
contracting with insurance companies or self-insuring) may find
universal ACIP recommendations sufficient motivation to include
immunizations as a covered benefit. Health insurers may decide on their
own to cover vaccine and administration costs for anyone covered by
their policies as well. Such policy changes could increase demand for
the vaccine among those who did not previously seek the vaccine because
it was not covered under their health insurance.

#### 2.3.3 Health Care Provider-Based Approaches

Many informants expressed the belief that the key to increasing demand
for the influenza vaccine is to change provider perceptions of the
importance of annual influenza vaccination for both vulnerable and
healthy populations. For many people, a health care provider's
recommendation can be the key to changing behaviors. Many strategies
have been recommended to encourage health care providers to offer the
influenza vaccine to their patients or to educate patients about the
value of annual influenza vaccination. Some of the most effective
strategies may be those that increase reimbursement levels for
vaccination. Prior to the 2005--2006 season, many providers complained
that Medicare's reimbursement for the influenza vaccine barely covered
the cost of the vaccine, much less the cost to administer the vaccine.
In response to studies that analyzed the costs of administering the
influenza and other vaccines (Coleman, Sangrujee, Zhou, & Chu, 2005),
Medicare raised vaccine administration reimbursement rates beginning in
the 2005--2006 season. Other provider-based approaches for increasing
vaccine demand that have been shown to be effective include standing
orders for vaccination and physician reminders (Briss et al., 2000).
Some contend that, before health care providers can successfully
encourage their patients to receive influenza vaccinations, health care
providers themselves need to improve their adherence with ACIP
recommendations. One study reports that only 38 percent of health care
workers comply (Harper et al., 2004).

#### 2.3.4 Pricing Changes

As described in Section 2.2, demand for the influenza vaccine may not be
very responsive to changes in price, especially for individuals whose
health insurance covers influenza vaccination (e.g., people on
Medicare). Data show that those with lower incomes who lack health
insurance have lower rates of vaccination (CDC, 2003). Such data suggest
that price may serve as a barrier to vaccination for some. For these
people, especially those in groups already targeted for vaccination,
lowering the price of the influenza vaccine could encourage them to
obtain an annual vaccination. A challenge of implementing this strategy
is to identify what price is low enough to encourage those who need and
want an annual influenza vaccination to get it. Prices charged for the
influenza vaccine in 2004--2005 ranged from about \$6.80 to \$8.50 per
dose. If targeted consumers would seek the vaccine only when prices are
\$5 or lower, government intervention may be necessary to subsidize
production costs to offer the vaccine at a low-cost to those of low
income---especially those who are in priority groups .

## 3. Roles for Stakeholders in Increasing Demand 

Given the complexity in increasing demand for influenza vaccine, a
number of stakeholders are involved. Based on our interviews with key
informants and a review of other relevant sources of information, we
describe the following roles for stakeholders in increasing demand for
influenza vaccine. We have adapted a list of stakeholders in the U.S.
influenza vaccination system created by the former director of CDC's
National Immunization Program, Walter Orenstein, and colleagues
(Orenstein, Douglas, Rodewald, & Hinman, 2005).

### 3.1 Federal Government

Although the vast majority of influenza immunizations are provided in
the private sector, the federal government is a significant stakeholder
in the means to increase demand for influenza vaccine. As one public
health expert explained,

> *The government can play a much larger role in educating the public of
> the importance of influenza immunization and the importance of the
> disease and, secondly, to also ensure that the physicians and health
> care providers, etc. that they're being appropriately reimbursed.*

This same expert further explained that funding policies for public
programs such as Medicare can indirectly affect private health
insurance,

> *The government sets the tone for private payers as well.
> Reimbursement done by Medicare, Medicaid, etc. kind of sets the tone
> for private payers, so adequate reimbursement to the physicians so
> that they don't feel that it's some sort of loss leader for them would
> be very encouraging.*

The federal government is also a source of information regarding
influenza immunization target groups. " ... \[ACIP\] recommendations
drive demand and demand drives supply." Through their recommendations
and health communications information, ACIP and CDC are key stakeholders
in efforts to inform the public.

> *... you need more targeted information. So to say, "it should go to
> people between 50 and 65 who are high-risk"* ... *People don\'t
> identify themselves as being high risk. They identify themselves as
> being diabetic, or having asthma. You can go to people and say,
> "you're in a high-risk category," and they will say "no I am not, I am
> diabetic."*

### 3.2 Vaccine Manufactures

Unlike the producers of some other pharmaceutical products, influenza
vaccine manufacturers have, by and large, not engaged in
direct-to-consumer marketing. In part this is due to the fact that
although there is more than one influenza vaccine manufacturer,
influenza vaccine is---in essence---a generic product. As such, an
influenza vaccine manufacture does not have a sufficient financial
interest in promoting its particular influenza vaccine product.
Nevertheless, casual observation would suggest that influenza vaccine
manufactures could provide a considerable amount of support to others
who are working to improve vaccine demand---especially given the benefit
that this would offer the influenza vaccine manufacturer.

Health care providers receive much of their information regarding what
should be prescribed and to whom from pharmaceutical sales
representatives (Avorn, Chen, & Hartley, 1983). Aside from influenza
vaccine, Sanofi Aventis (Sanofi Pasteur's parent pharmaceutical
company[^7]), Chiron, and MedImmune do not have other pharmaceutical
products that are designed for a broad portion of the public. As such,
one may speculate that sales representatives from these companies are
not likely to have the opportunity to provide information to health care
providers promoting influenza vaccine. As GlaxoSmithKline (GSK)---a
company with a broader array of pharmaceutical products that target more
diseases---enters the U.S. market, it will be interesting to see how its
pharmaceutical sales representatives may play a role in providing health
care providers with information promoting influenza vaccination.

### 3.3 State and Local Governments

Like the federal government, state and local governments have key roles
in health promotion and disease prevention. In addition to a modest role
in vaccine delivery through public clinics, state and local governments
are in a position to establish public information campaigns to improve
the public's understanding of influenza and the benefits of
immunization. Likewise, states are in a position to educate business
leaders and health insurers about the benefits of including vaccine
coverage in their policies and practices.

### 3.4 Wholesalers

Although wholesalers and other distributors may not be primary
stakeholders in improving demand for influenza vaccine, as they are the
ones who are most often in a health care provider's office or clinic,
they can work to provide information to health care providers and other
office or clinic staff. As described more thoroughly in the companion
brief, *Influenza Vaccine: Who Buys it and Who Sells It*, wholesalers
often have a long-standing relationship with health care providers and
offer a variety of products ranging from the paper that covers
examination tables to cotton balls and alcohol swabs.

### 3.5 Professional Organizations

One of the ironies regarding influenza immunization rates is the
observation that so few health care workers (HCW's) receive annual
influenza immunization. Influenza vaccination is associated with reduced
mortality among HCW's patients (Wilde et al., 1999). Nevertheless,
according to the 2002 National Health Interview Survey, only 38 percent
of HCW's reported receiving an influenza immunization (Harper, Fukuda,
Uyeki, Cox & Bridges, 2004). A persuasive article outlines "seven truths
we must accept" to increase health care workers' influenza vaccination
rates (Poland, Tosh, & Jacobson, 2005). Professional organizations are
in a position to promote and otherwise facilitate members' receipt of
annual influenza immunizations. As one key informant explained, "I think
that you need to get doctors to get their own clinical staff to get
vaccinated so they can essentially carry the message to patient."

### 3.6 Health Insurance Companies

Health insurance companies are in a position not only to provide
coverage for influenza immunization but to use immunization rates as a
benchmark against which health care provider performance can be
measured. The National Committee for Quality Assurance (NCQA) already
includes influenza immunizations among those 50 years of age or older
among Health plan Employer Data and Information Set (HEDIS) indicators,
which are used to determine health plans' adherence with various health
promotion efforts. HEDIS measures can also be used by employers that are
choosing which insurance to offer to its employees and by individuals
who are selecting health plans. As such, HEDIS measures of influenza
vaccination coverage can potentially influence health insurance
purchasers or potential enrollees.

In addition, health insurance companies could potentially offer
incentives for participating health care providers as an additional
effort to improve immunization rates among their patients. One key
informant described an array of approaches to improve immunization
rates:

> *You could be building incentives for immunization levels into the HMO
> contracts. We don't do that. Medicare could be doing the same
> thing---and this is just the reimbursement end of things ... If you
> don't have accountability to tie you down to some contractual
> agreement, where they did what they did like in Great Britain where
> they paid for performance using individual office assessments, we're
> not going to see it happen. ... I don't mean in a punitive way ... if
> you go into offices and if they know you're coming in to look at
> immunization rates and compliance, it actually goes up. ... It's a
> whole series of things from the administrative side. The regulatory
> side---... states could \[be\] doing more to require performance from
> plans---that they have to meet certain goals in the area of
> immunization practice. And have it graded, or at least benchmarked
> against yourself.*

### 3.7 Private Health Care Providers

Private health care providers are the traditional source of
immunization. They have direct contact with persons who could
potentially be immunized. As such, they are in a prime position to
ensure that their patients receive recommended immunizations.
Nevertheless, the literature shows that so-called "missed
opportunities"[^8] are common (Nowalk, Zimmerman, & Feghali, 2004).

> *... at some point the person who supplies the vaccine, theoretically
> the physician, convinces the person they need to get vaccinated. So
> it's hard to talk about increasing demand if you don't find ways to
> encourage physicians to offer it more broadly.*

Assuring that health care providers offer vaccine is important,
especially in light of recent events that have led some health care
providers to no longer offer influenza vaccinations. As one wholesaler
explained, "physicians---some of them---are saying, "We're not even
going to try to plan for vaccinating." Physicians offering influenza
vaccine in their practices can increase demand (by being able to offer
immunization on site and reduce missed opportunities). This, in turn,
can help to increase supply.

## 4. Summary and Conclusion

Although influenza vaccine supply and demand are integrally linked,
increasing demand has the potential to not only spur influenza supply
but promote the public's health as well. In our key informant
interviews, the significance of demand and ways to promote influenza
vaccine demand arose frequently. One key informant observed,

> *... there're two elements of demand. Demand of provider and demand of
> consumer. One doesn't always equate to the other. I say that because
> many providers have backed out of the flu immunization business
> because of the craziness of it---the unpredictability of it. And I
> think there's an impact of that on consumer demand. If physicians
> aren't really aggressive about making sure they have flu vaccine in
> their offices, then they're more likely---I think---not to be as
> aggressive in encouraging their patients to pursue it.*

In summary, demand for influenza vaccine is a critical component in the
complex means to reduce the public's risk from a leading cause of
morality and morbidity. The means to improve demand are complicated and
include roles for a variety of stakeholders.

## References

Advisory Committee on Immunization Practices (1999, April 30).
Prevention and control of influenza: Recommendations of the Advisory
Committee on Immunization Practices (ACIP). *Morbidity and Mortality
Weekly Reports, 48*(RR-04), 1--28. Retrieved October 5, 2005, from
<http://www.cdc.gov/mmwr/preview/mmwrhtml/00057028.htm>

Advisory Committee on Immunization Practices (2000, April 14).
Prevention and control of influenza: Recommendations of the Advisory
Committee on Immunization Practices (ACIP). *Morbidity and Mortality
Weekly Reports, 49*(RR03), 1--38. Retrieved October 4, 2005, from
<http://www.cdc.gov/mmwr/preview/mmwrhtml/rr4903a1.htm>

Advisory Committee on Immunization Practices (2001, April 20).
Prevention and control of influenza: Recommendations of the Advisory
Committee on Immunization Practices (ACIP). *Morbidity and Mortality
Weekly Reports, 50*(RR04), 1--46. Retrieved October 5, 2005, from
<http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5004a1.htm>

Avorn, J., Chen, M., & Hartley, R. (1983). Scientific versus commercial
sources of influence on the prescribing behavior of physicians.
*American Journal of Medicine; 73*:4-8.

Bridges, C.B., Fukuda, K., Uyeki, T.M., Cox, N.J., & Singleton, J.A.
(2002, April 12). Prevention and control of influenza: Recommendations
of the Advisory Committee on Immunization Practices (ACIP). *Morbidity
and Mortality Weekly Reports, 51*(RR03), 1--31. Retrieved October 5,
2005, from <http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5103a1.htm>

Bridges, C.B., Harper, S.A., Fukuda, K., Uyeki, T.M., Cox, N.J., &
Singleton, J.A. (2003, April 25). Prevention and control of influenza:
Recommendations of the Advisory Committee on Immunization Practices
(ACIP). *Morbidity and Mortality Weekly Reports, 52*(RR08), 1--36.
Retrieved October 5, 2005, from
<http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5208a1.htm>

Briss, P.A., Rodewald, L.E., Hinman, A.R., Shefer, A.M., Strikas, R.A.,
Bernier, R.R., Carande-Kulis, V.G., Yusuf, H.R., Ndiaye, S.M., &
Williams, S.M. (2000). Reviews of evidence regarding interventions to
improve vaccination coverage in children, adolescents, and adults. The
Task Force on Community Preventative Services. *American Journal of
Preventive Medicine*, *18*(Suppl 1), 97--140.

Centers for Disease Control and Prevention (CDC). (1999, 2002, 2003).
*Behavioral Risk Factor Surveillance System Survey Data*. Atlanta,
Georgia: U.S. Department of Health and Human Services, Centers for
Disease Control and Prevention.

Centers for Disease Control and Prevention (CDC) (2000). Immunization
and infectious diseases, Vaccine coverage and strategies (objective 14).
In: *Healthy People 2010*. Retrieved October 4, 2005, from
<http://www.healthypeople.gov/Document/tableofcontents.htm>

Centers for Disease Control and Prevention (CDC) (2003, October 10).
Racial/ethnic disparities in influenza and pneumococcal vaccination
levels among persons aged ≥ 65 years---United States 1989--2001.
*Morbidity and Mortality Weekly Reports,* *52*(40), 958--962. Retrieved
October 4, 2005, from
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5240a3.htm>

Centers for Disease Control and Prevention (CDC) (2004, November 5).
Influenza vaccination and self-reported reasons for not receiving
influenza vaccination among Medicare beneficiaries aged ≥ 65
years---United States, 1991--2002, *Morbidity and Mortality Weekly
Reports,* *53*(43), 1012--1015. Retrieved October 4, 2005 from
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5343a3.htm>

Centers for Disease Control and Prevention (CDC) (2005a, July 2).
Update: Influenza activity---United States and worldwide, 2003--04
season, and composition of the 2004--05 influenza vaccine. *Morbidity
and Mortality Weekly Reports 53*(25), 547--552. Retrieved October 24,
2005, from <http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5325a1.htm>

Centers for Disease Control and Prevention (CDC) (2005b, July 28).
*Interim estimates of populations targeted for influenza vaccination
from 2003 National Health Interview Survey data and estimates for 2004
based on influenza vaccine shortage priority groups*. Retrieved
September 23, 2005, from
<http://www.cdc.gov/flu/professionals/vaccination/pdf/targetpopchart.pdf>

Centers for Disease Control and Prevention (CDC) (2005c, September 2).
Update: Influenza vaccine supply and recommendations for prioritization
during the 2005--06 influenza season. *Morbidity and Mortality Weekly
Reports*, *54*(34), 850. Retrieved September 23, 2005, from
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5434a4.htm>

Charatan, F. (2004). Widespread flu in United States exposes shortage of
vaccine. *BMJ*, *328*(7430), 8. Retrieved January 3, 2004,
<http://bmj.bmjjournals.com/cgi/content/full/328/7430/8-a>

Coleman, M.S., Snagrujee, N. Zhou, F. & Chu, S. (2005). Factors
affecting U.S. manufacturers' decisions to produce vaccines. *Health
Affairs (Millwood) 24*(3), 635--642.

DesRoches, C.M., Blendon, R.J., & Benson, J.M. (2005). Americans'
responses to the 2004 influenza vaccine shortage. *Health Affairs
(Millwood), 24*(3), 822--831.

Fishbein, D.B., Fontanesi, J., Kopald, D., Stevenson, J., Bennett, N.M.,
Stryker, D.W., Long, C., Coleman, M.S., & Schefer, A. (2005, in press).
Why patients do not receive influenza vaccine in December and January.
*Vaccine.*

Gershman, K., Smith, R., & Trefren, L. (2004). Lessons learned:
Colorado's 2004 flu experience. *NACCHO Exchange*, *2*(4), 13--15.
Retrieved October 4, 2005, from
<http://archive.naccho.org/Documents/naccho-exchange-spring-04.pdf>

Harper, S.A., Fukuda, K., Uyeki, T.M., Cox, N.J., & Bridges, C.B. (2004,
May 28). Prevention and control of influenza: Recommendations of the
Advisory Committee on Immunization Practices (ACIP). *Morbidity and
Mortality Weekly Reports, 53*(RR06), 1--40. Retrieved October 4, 2005,
from <http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5306a1.htm>

Harper, S.A., Fukuda, K., Uyeki, T.M., Cox, N.J., & Bridges, C.B. (2005,
July 29). Prevention and control of influenza: Recommendations of the
Advisory Committee on Immunization Practices (ACIP). *Morbidity and
Mortality Weekly Reports, 54*(RR08), 1--40. Retrieved October 5, 2005,
from <http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5408a1.htm>

Hebert, P.L., Frick, K.D., Kane, R.L., & McBean, A.M. (2005). The Causes
of racial and ethnic differences in influenza vaccination rates among
elderly medicare beneficiaries. *HSR: Health Services Research 40*(2),
517-537

Helms, C.M., Guerra, F.A., Klein, J.O., Schaffner, W., Arvin, A.M., &
Peter, G. (2005). Strengthening the nation\'s influenza vaccination
system: A National Vaccine Advisory Committee assessment. *American
Journal of Preventive Medicine, 29*(3), 221--226.

[Mitka
M.](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15479921&query_hl=7)
(2004). Health officials brace for flu season. *Journal of the American
Medical Association, 292*(14), 1670--1671.

Nowalk, M.P., Zimmerman, R.K. & Feghali, J. (2004). Missed opportunities
for adult immunization in diverse primary care office settings. *Vaccine
22*, 3457-3463.

Nowalk, P. (2005). Parental perspectives on influenza immunization of
children aged 6 to 23 months. *American Journal of Preventive Medicine*,
*29*(3), 210--214.

Orenstein, W.A., Douglas, R.G., Rodewald, L.E., & Hinman, A.R. (2005).
Immunizations in the United States: Success, Structure, and Stress.
*Health Affairs*, *24*(3), 599--610.

Pauly, M.V. (2005). Improving vaccine supply and development: Who needs
what? *Health Affairs (Millwood), 24*(3), 680--689.

Poland, G.A., Tosh, P., & Jacobson, R.M. (2005). Requiring influenza
vaccination for health care workers: Seven truths we must accept.
*Vaccine 23*, 2251--2255.

Thompson, W.W., Shay, D.K., Weintraub, E., Brammer, L., Bridges, C.B.,
Cox, N.J, & Fukuda, K. (2004). Influenza-associated hospitalizations in
the United States. *Journal of the American Medical Association,
292*(11), 1333--1340.

Thompson, W.W., Shay, D.K., Weintraub, E., Brammer, L., Cox, N.,
Anderson, L.J., & Fukuda, K. (2003). Mortality associated with influenza
and respiratory syncytial virus in the United States. *Journal of the
American Medical Association, 289*(2), 179--186.

Wilde J.A., McMillan J.A., Serwint, J., Butta, J., O'Riordan, M.A. &
Steinhoff, M.C. (1999). Effectiveness of influenza vaccine in health
care professionals: a randomized-trial. *Journal of the American Medical
Association, 281*, 908-13.

Zimmerman, R.K., Santibanez, T.A., Janosky, J.E., Fine, M.J., Raymund,
M., Wilson, S.A., Bardella, I.J., Medsger, A.R., Nowalk, M.P. (2003).
What affects influenza vaccination rates among older patients? An
analysis from inner-city, suburban, rural, and Veterans Affairs
practices. *American Journal of Medicine*, *114*(1), 31--38.

[^1]: As detailed in the companion brief, *Influenza Vaccine
    Manufacturing*, influenza vaccine is generally administered annually
    between October and December.

[^2]: *Healthy People 2010* established the annual influenza vaccination
    goal of 90 percent coverage for noninstitutionalized adults ≥ 65
    years of age. In 2003, 65 percent of adults ≥ 65 years of age
    reported receiving an influenza immunization in the previous year
    (CDC, 2005b).

[^3]: Priority groups include persons 65 years of age or older, persons
    of any age with chronic diseases, pregnant women, children 6 to 23
    months of age, health care personnel, and household contacts of
    previously listed groups. Target (or targeted) groups include
    priority groups plus healthy adults 50 to 64 years of age.

[^4]: The survey was conducted following the 2002--2003 influenza season
    during which ACIP "encouraged" children 6 to 23 months of age to
    receive influenza immunization "whenever feasible."

[^5]: The Council of State and Territorial Epidemiologists (CSTE) and
    CDC are working to implement a national notification system for
    influenza-associated pediatric mortality.

[^6]: The MCBS is a nationally representative survey conducted by the
    Centers for Medicare & Medicaid Services.

[^7]: In 2004, Sanofi merged with Aventis Pasteur to create the Sanofi
    Aventis Group. The vaccine division of the Sanofi Aventis Group
    changed its name to Sanofi Pasteur.

[^8]: Missed opportunities are situations in which an individual who
    should receive an immunization and is in a location where
    immunizations are provided (most notably a physicians' office,
    clinic, or hospital) does not receive one.