Safety and Efficacy of an H1N1 Influenza Vaccine in People With Asthma

A new swine-origin influenza A/H1N1 virus was recently identified as a significant cause of respiratory illness in Mexico and the United States. In response, the World Health Organization (WHO) declared a pandemic on June 11, 2009. Current data indicates that licensed seasonal influenza vaccines are not likely to provide protection against the new H1N1 virus. Development and deployment of a vaccine for the new H1N1 virus, particularly to at-risk populations, is essential. Groups at risk for influenza yearly include the elderly and those with asthma, and current guidelines from the Advisory Committee on Immunization Practices (ACIP) recommend vaccination of adults and children with asthma. Early, unpublished data on US patients hospitalized by H1N1 infection indicates that many had underlying asthma, and it is expected people with asthma will be on a priority list for H1N1 influenza vaccination. Data also indicate that increased dosage of vaccines may increase development of antibodies and that use of certain inhalers may affect immunization. This study will test the safety and immunogenicity of an unadjuvanted, inactivated H1N1 vaccine at two dosage levels in people with asthma. Participation in this study will last approximately 34 weeks. Participants will be stratified into two groups: those with mild to moderate versus those with severe asthma. All participants will be randomly assigned to receive either a high dose (30 mcg) or low dose (15 mcg) H1N1 vaccine. Both vaccine dosages will be administered in two intramuscular injections 21 days apart. Participants assigned to the higher dose (30 mcg) will receive two injections of the 15 mcg vaccine at each administration. Participants will complete study visits at entry, administration of the vaccines on Days 1 and 21, follow-ups a week after each vaccine injection, and 21 days after the second injection. Measurements at these visits will include spirometry (measurement of air entering and leaving the lungs), a questionnaire about asthma, a targeted physical examination, an adverse event and medication assessment, inspection of vaccination site, and collection of a blood sample. A urine sample will be collected for pregnancy test before each vaccination. In additions, for 8 days after each vaccination injection participants will keep a diary recording oral temperature, adverse events, asthma symptoms, and use of inhalers. These diaries will be reviewed at study visits. Participants will also receive follow-up phone calls to assess safety 60, 120, and 180 days after the last vaccine injection.