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December 13, 2010

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NIH Trial of 2009 H1N1 Influenza Vaccine in People with Asthma

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1.    Why was it important to test 2009 H1N1 influenza vaccine in people with asthma?


Each year, the Centers for Disease Control and Prevention (CDC) recommends that people with asthma receive the seasonal influenza vaccine to prevent getting the flu, which may seriously worsen their asthma and thereby increase their risk of severe influenza disease.

People with asthma also were at higher risk of complications following infection with 2009 H1N1 influenza virus. Review of hospital records from February 2009 to April 2010 by CDC from the disease outbreak in the United States found that although asthma occurs in about 8 percent of the U.S. population, approximately 30 percent of people hospitalized due to 2009 H1N1 influenza had asthma.

In the fall of 2009, U.S. public health officials, following the recommendation of the CDC’s Advisory Committee on Immunization Practices, designated people with underlying medical conditions, including asthma, among the top priority groups to receive the 2009 H1N1 influenza vaccine.

This clinical trial of 2009 H1N1 influenza vaccine in people with asthma provided information to public health officials to help answer questions including what dosage and how many doses of vaccine are needed to elicit immune responses indicative of protection against the 2009 H1N1 virus.

People with severe asthma receive high doses of corticosteroids by inhalation and some of them even receive corticosteroids orally or by injections. Sometimes, corticosteroids can suppress the immune system. Therefore, it was important to examine whether the immune response to the H1N1 influenza vaccine was adequate in people with asthma receiving high doses of corticosteroids.

2.   Who conducted the 2009 H1N1 influenza vaccine trial in people with asthma?

  The National Institute of Allergy and Infectious Diseases (NIAID) and the National Heart, Lung and Blood Institute (NHLBI) supported this trial. It was conducted by the NHLBI Severe Asthma Research Program (SARP), a collaborative research program investigating the pathophysiology of severe asthma in adults and children and how it differs from mild to moderate asthma.

3.   When did the trial begin?

    The first volunteers to take part in this study received their initial dose of 2009 H1N1 influenza vaccine on Oct. 16, 2009.

4.   What was the design of the 2009 H1N1 influenza vaccine trial in people with asthma?


The study enrolled 390 adolescents and adults aged 12 to 79 years with mild, moderate or severe asthma. Participants were categorized by asthma severity into two groups (mild/moderate and severe); by age into four groups (12 to 21 years old, 21 to 39 years old, 40 to 59 years old, and older than 60). A total of 217 people with mild/moderate asthma and a total of 173 people with severe asthma were enrolled in the trial. They were randomly divided within each asthma category to receive a low or high dosage of the inactivated 2009 H1N1 influenza vaccine. The trial was open-label, meaning that the clinicians and participants knew the dosage of vaccine administered.

All participants received two injections of the vaccine spaced three weeks apart. A total of 110 individuals with mild or moderate asthma and 87 individuals with severe asthma received 15-microgram doses of the vaccine. A total of 107 individuals with mild or moderate asthma and 86 individuals with severe asthma received 30-microgram doses of the vaccine. The 30-microgram dose of the vaccine was administered as two 15-microgram injections, one in the muscle of each arm or thigh.

A total of five clinic visits were required during the study period. Vaccine injections were administered on days 1 and 21 of the study. During visits, blood samples were taken and lung function assessed. Every day for one week after each vaccine injection, study participants completed diaries tracking any irritation they observed at the injection site or generalized symptoms they had, which are well-known to occur after vaccinations (e.g., fever, fatigue, etc.).

All participants were provided with a diary on day 1 to track their asthma symptoms and record the number of times they took asthma medications during the study period. Study investigators reviewed diary entries at each of the five clinic visits. Follow-up telephone calls to track participants’ health status were conducted for 6 months after the second dose of the vaccine was given.

The major goal of the study was to determine if people with severe asthma (who were those taking high doses of corticosteroids) require one or two doses of the standard vaccine (15 micrograms) or if they need a higher dose (30 micrograms). Study investigators looked for indications of immune system responses, such as the production of antibodies against 2009 H1N1 influenza virus. Blood samples drawn at set time points following the first and second injections provided information about the immune response to the vaccine. The safety of the vaccine in people with asthma also was assessed.

A detailed description of the study can be found at

5.   Who participated in the study?


The trial enrolled 390 males and non-pregnant females aged 12 to 79 years with mild, moderate or severe asthma.

The study population was drawn from individuals with asthma who had previously participated in a SARP study, as well as from asthma and other clinics in the participating academic institutions.

Participants were extensively characterized with respect to their asthma severity, lung function and airway inflammation. Asthma severity is largely distinguished by the amount and frequency of corticosteroids needed to control asthma symptoms. People with mild disease may not need corticosteroids or may require low doses of inhaled corticosteroids; those with moderate asthma need low to moderate doses of inhaled corticosteroids; and those with severe asthma need high doses of inhaled corticosteroids and frequently use oral corticosteroids.

6.   Where did the study take place?

    The seven study sites included Cleveland Clinic Foundation; Emory University, Atlanta; University of Pittsburgh Asthma Institute; University of Virginia, Charlottesville; University of Wisconsin, Madison; Wake Forest University, Winston-Salem, NC; and Washington University, St. Louis. Each site enrolled 25 to 75 study participants.

7.   What vaccine was tested in this trial?

    The trial tested a 2009 H1N1 influenza vaccine produced by Novartis Vaccines and Diagnostics Ltd. in its facility in Speke, Liverpool, United Kingdom. The vaccine was made from an inactivated 2009 H1N1 flu virus and did not contain an adjuvant, a substance added to a vaccine to enhance the immune response.

8.   How did the 2009 H1N1 influenza vaccine tested in this trial compare with the regular seasonal flu vaccine?

    The candidate 2009 H1N1 flu vaccine tested in this clinical trial was very similar to the annual seasonal influenza vaccine recommended by CDC for all people with asthma. The 2009 H1N1 vaccine was produced in the same way as most seasonal flu vaccines—virus is grown in fertilized chicken eggs and then inactivated for use in the vaccine.

9.   How was safety monitored in the trial?

    Safety was closely monitored throughout the trial, both by the study investigators and by an independent panel of experts known as a Data and Safety Monitoring Board (DSMB). This board is convened by NIAID to review the data from this trial. The DSMB conducted regularly scheduled meetings during the course of the trial.

10.   How long did the trial last?

    The study lasted approximately seven months, including clinic visits for the first three weeks and follow-up phone calls over a six-month period.

11.   Where are results from the trial published?

    Results of the trial are available online in the Journal of Allergy and Clinical Immunology.

12.   Where can I get more information on other NIH-sponsored clinical trials of 2009 H1N1 influenza vaccines?

    For information about other NIAID-sponsored clinical trials of 2009 H1N1 flu vaccines, visit the H1N1 (Swine Flu) Web portal.

13.   Where can I get additional information on influenza and asthma?

    Visit the CDC Web site for information for the general public and for healthcare providers about seasonal influenza and asthma, 2009 H1N1 influenza in people with asthma, avian and pandemic influenza, and asthma.

Media inquiries can be directed to the NIAID Office of Communications at 301-402-1663,

NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit

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Last Updated December 16, 2010

Last Reviewed October 15, 2009