A general dose of H1N1 influenza vaccine works well in people who have asthma but in case of severe asthma condition a higher dose of the vaccine is preferred, says a government-sponsored study.
H1N1 influenza vaccine in people with asthma indicates that a single dose of vaccine was safe and induced a strong immune response predictive of protection.
The findings also suggest that individuals over the age of 60 who have severe asthma may require a larger dose of vaccine.
"The results of this clinical trial show that the 2009 H1N1 influenza vaccine was safe and led to adequate production of antibodies thought to be protective against the virus," NIAID Director Anthony S. Fauci said.
In late 2009, National Institute of Allergy and Infectious Diseases /NIH rapidly designed and sponsored a clinical study to determine the dose and number of doses of the 2009 H1N1 influenza vaccine needed to safely produce a protective immune response in people with asthma.
In these trials, a single dose of the vaccine containing 15 micrograms of the influenza hemagglutinin molecule-the main target of the protective antibody response-was found to be well tolerated and induced a strong immune response in most participants.
The study enrolled 390 people aged 12 to 79 years with asthma.
Half of the participants in each group received a 15-microgram dose of vaccine, and the other half received a 30-microgram dose, both by injection.
In participants with mild to moderate asthma, and in most participants with severe asthma, a single 15-microgram dose was sufficient to induce a presumably protective immune response.
Participants older than age 60 with severe asthma had diminished immune responses to the 15-microgram dose of vaccine, but the 30-microgram dose gave an adequate response.
The findings appeared online in the Journal of Allergy and Clinical Immunology.