2009 H1N1 Influenza -- Just the Facts: Vaccine Essentials

John G. Bartlett, MD


November 23, 2009

In This Article

Will People Get the Vaccine?

Uptake by priority groups for vaccination is not easily predicted, but it is noteworthy that the current (seasonal) vaccine recommendations apply to 83% of the US population, but only 40% to 44% actually receive a yearly flu vaccine. The group with the highest adherence for having a seasonal influenza immunization is the elderly, a group that is not targeted for the pandemic H1N1 flu vaccine. Persons over 65 years of age have a seasonal flu vaccination rate of 66%; HCWs have an embarrassingly low vaccination rate of 40%-44%. According to a Red Cross telephone survey of 1002 adults, 60% of Americans plan to get the 2009 H1N1 influenza vaccine, and 60% claim that they are not worried about H1N1 influenza A. (American Red Cross. Red Cross survey finds overwhelming majority of public taking steps against H1N1 flu virus. August 27, 2009.)

Consumer Reports conducted a nationally representative telephone survey of 1502 adults from September 2 to 7 to determine the demand for 2009 H1N1 vaccine. (Morgan D. Majority of U.S. parents wary about H1N1 vaccine: Poll. Reuters. September 30, 2009.) Results were as follows:

  • Percentage who want the H1N1 vaccine: 34%;

  • Percentage who are undecided about the H1N1 vaccine: 43%;

  • Percentage who will definitely get their children vaccinated against H1N1: 35%;

  • Percentage who are undecided about getting their children vaccinated against H1N1: 50%;

  • Percentage who had flu vaccine last flu season: 41%;

  • Rationale for not getting children vaccinated: desire to have children develop natural immunity and concern for adequacy of the testing;

  • Factors deemed most important for keeping children healthy in flu season: healthy diet (89%), adequate sleep (83%), keeping children away from sick children (68%).

The Associated Press conducted a poll of attitudes on 2009 H1N1 vaccine. In a telephone survey of 1003 adults, they found:

  • Percentage of parents unlikely to give permission for their children to be vaccinated at school: 38%

  • Percentage worried about side effects of vaccine: 72%

(GfK Roper Public Affairs and Media. The AP-GfK Poll. October 1-5, 2009. Available at: http://surveys.ap.org/data/GfK/AP-GfK%20Poll%20Final%20FLU%20Topline%20100609.pdf Accessed October 12, 2009.)

Vaccine coverage in the United States, 2008-2009. For a historical look at willingness to get influenza vaccine, an analysis of vaccine coverage for the 2008-2009 seasonal influenza vaccine was based on the Behavioral Risk Factor Surveillance System, which represents 3% of the US population. The results showed the following influenza vaccination rates:

  • > 65 years: 67%;

  • 50-64 years: 42%;

  • 18-49 years: 32%;

  • 5-17 years: 21%;

  • 2-4 years: 32%; and

  • 6-23 months: 41%.

(CDC. Influenza vaccination coverage among children and adults. MMWR Morb Mortal Wkly Rep. 2009;58:1091-1095.)

Pregnant Women and Newborns

Pregnant women are a high priority for vaccination against both 2009 H1N1 and seasonal influenza. The vaccine is considered safe in pregnancy, and both the mother and the infant are at high risk for complications of influenza. The vaccine to the mother elicits antibody that persists in the infant during the first 6 months when the infant is particularly vulnerable.

Healthcare Workers

The ACIP has identified HCWs as a high priority for influenza vaccine since 1984. (CDC Advisory Committee on Immunization Practices. Prevention and control of influenza. Ann Intern Med. 1984;101:218-222.) This issue has been reviewed and policy recommendations have been provided by the Society for Healthcare Epidemiology of America (SHEA). (Talbot TR, Bradley SE, Cosgrove SE, Ruef C, Siegel JD, Weber DJ. Influenza vaccination of healthcare workers and vaccine allocation for healthcare workers during vaccine shortages. Infect Control Hosp Epidemiol. 2005;26:882-890.)

The rationale for immunizing HCWs is to protect both HCWs and patients. The risk to patients is demonstrated by high rates of nosocomial infections due to provider-to-patient transmission, and surveys show that up to 76% of HCWs continue to work when they have a flulike illness. (Weingarten S, Riedinger M, Bolton LB, Miles P, Ault M. Barriers to influenza vaccine acceptance. A survey of physicians and nurses. Am J Infect Control. 1989;17:202-207. Lester RT, McGeer A, Tomlinson G, Detsky AS. Use of, effectiveness of, and attitudes regarding influenza vaccine among house staff. Infect Control Hosp Epidemiol. 2003;24:839-844.)

Measurement of Influenza Vaccination Coverage Among Healthcare Personnel in US Hospitals

(Lindley MC, Yonek J, Ahmed F, Perez JF, Torres GW. Measurement of influenza vaccination among healthcare personnel in US hospitals. Infect Control Hosp Epidemiol. 2009 Oct 22. [Epub ahead of print])

  • Purpose: Assess the uptake of influenza vaccine by HCWs in US hospitals.

  • Methods. A total of 996 questionnaires were sent to directors of infection control to assess hospital vaccination policies and vaccination coverage. The survey applied to the 2005-2006 influenza season.

  • Response rate: Responses were received from 555 of 996 (56%) hospitals. More than 99% of hospitals provide flu vaccination to employees without charge.

  • Results: Hospitals that vaccinated:

    • Credentialed medical staff: 94%

    • Contract staff: 83%

    • Volunteers:86%

    • Medical students and residents: 58%

    • Hospitals that tracked vaccinations by unit or type of staff: 92%

    • Documentation that the vaccine was not taken: 19%

    • Signed refusals: 16%

    • Hospitals that tracked vaccination coverage: 69%

    • Coverage in hospitals that tracked immunization coverage: mean, 55%

  • Conclusion: The CDC objective for Healthy People 2010 is influenza vaccination for at least 60% of HCWs. It is unlikely that this goal will be achieved because there was no change in vaccination rate from a similar questionnaire in 2007. An unpublished National Health Interview Survey in 2007 showed a vaccination rate in HCWs of 46%.

The discussion noted that another factor that influenced vaccination rates was that only 6 states required hospital employees to be vaccinated and/or required hospitals to report vaccination rates to state health departments. The CDC has a Website that can be used to determine whether a particular state has any law or regulation about vaccination in HCWs. (CDC. State immunization laws for healthcare workers and patients. Available at: http://www2a.cdc.gov/nip/StateVaccApp/statevaccsApp/default.asp Accessed November 3, 2009.)

Policy and Legislation for HCW Flu Vaccination

Policies for influenza vaccination for HCWs are generally institutionally based, although some states have proposed legislation that would make vaccination mandatory for HCWs unless contraindicated. (Poland GA, Tosh P, Jacobson RM. Requiring influenza vaccination for health care workers: seven truths we must accept. Vaccine. 2005;23:2251-2255.)

A number of other health systems now require vaccination for HCWs, including Emory Hospital in Atlanta, University of Pennsylvania Hospitals, University of Maryland's 11 hospitals, Loyola Health Systems in Chicago, Virginia Mason Medical Center in Seattle, University of Iowa, MedStar (25,000 HCWs) (CBS. Health workers protest flu vaccine mandate. CBS Evening News. October 4, 2009. Available at: http://www.cbsnews.com/stories/2009/10/04/eveningnews/main5362636.shtml Accessed October 9, 2009.)

Mandatory Influenza Vaccine for Healthcare Workers

  • The CDC reports that 48% of healthcare workers receive influenza vaccinations.

  • The Infectious Diseases Society of America called for mandatory influenza vaccination of healthcare workers, citing the role of vaccines in protecting vulnerable patients.

  • New York State mandated flu vaccination for healthcare workers but rescinded the requirement, citing shortages of H1N1 vaccine. Unions also challenged the requirement.

  • The University of Iowa Hospitals and Clinics, with 6300 workers, also discontinued their mandate for vaccination when Service Employees International Union (SEIU) won an arbitration hearing. The University reported an immunization rate of 86% last year.

  • Cook County Health and Hospitals System in Chicago mandated seasonal and pandemic flu vaccination for 11,000 employees to be effective October 13, but delayed the H1N1 vaccine requirement to December 1.

  • Health Corporation of America mandated vaccination for 120,000 employees, but delayed the October 1 deadline because of supply delays. (Young A. Flu shots for workers hit sticking point. November 5, 2009. Available at: http://www.usatoday.com/news/health/2009-11-05-swine-flu-workers_N.htm Accessed November 10, 2009.)

Recommendation From SHEA for Increasing Vaccine Adherence in HCWs

  1. Targeted education;

  2. Provide vaccine at no cost and at convenient locations and times;

  3. Require HCWs to receive vaccine, or to sign a declination each year if they refuse vaccination after participating in an educational program or have a medical contraindication; and

  4. Maintain facility surveillance.

Alternative Plan for Vaccine Allocation

An alternative proposal for vaccine priority has been presented by Medlock and Galvani. The authors recommend vaccinations for persons 5-19 years and 30-39 years as the optimal method to control the epidemic and reduce deaths. This would target school-age children and their parents -- the most important vehicles of transmission -- and would be more effective than the CDC plan, which they consider "suboptimal." The potential outcome of the Medlock model compared with the ACIP plan is shown in Table 2. (Medlock J, Galvani AP. Optimizing influenza vaccine distribution. Science. 2009 Aug 20. [Epub ahead of print].)

Table 2. Outcome of the ACIP Priorities vs the "Medlock Plan"

Plan Cases Deaths Cost
ACIP 59 million 139,000 $67 billion
Medlock 44 million 108,000 $53 billion

ACIP = Advisory Committee on Immunization Practices
From: Medlock J, Galvani AP. Optimizing influenza vaccine distribution. Science. 2009 Aug 20. [Epub ahead of print].


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