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N Engl J Med. Response to a Monovalent 2009 Influenza A (H1N1) Vaccine
Response to a Monovalent 2009 Influenza A (H1N1) Vaccine (N Engl J Med., abstract, edited)
Response to a Monovalent 2009 Influenza A (H1N1) Vaccine
Michael E. Greenberg, M.D., M.P.H., Michael H. Lai, B.Med.Sc., M.B., B.S., M.Med.Sc., Gunter F. Hartel, M.S., Ph.D., Christine H. Wichems, Ph.D., Charmaine Gittleson, B.Sc., M.B., B.Ch., Jillian Bennet, M.Sc., M.P.H., Gail Dawson, B.Pharm., Wilson Hu, M.D., M.B.A., Connie Leggio, B.Sc., Diane Washington, M.D., and Russell L. Basser, M.B., B.S., M.D., F.R.A.C.P.
ABSTRACT
Background
A novel 2009 influenza A (H1N1) virus is responsible for the first influenza pandemic in 41 years. A safe and effective vaccine is needed. A randomized, observer-blind, parallel-group trial evaluating two doses of an inactivated, split-virus 2009 H1N1 vaccine in healthy adults between the ages of 18 and 64 years is ongoing at a single site in Australia.
Methods
We evaluated the immunogenicity and safety of the vaccine after each of two scheduled doses, administered 21 days apart. A total of 240 subjects, equally divided into two age groups (<50 years and ≥50 years), were enrolled and underwent randomization to receive either 15 ?g or 30 ?g of hemagglutinin antigen by intramuscular injection. We measured antibody titers using hemagglutination-inhibition and microneutralization assays at baseline and 21 days after vaccination. The coprimary immunogenicity end points were the proportion of subjects with antibody titers of 1:40 or more on hemagglutination-inhibition assay, the proportion of subjects with either seroconversion or a significant increase in antibody titer, and the factor increase in the geometric mean titer.
Results
By day 21 after the first dose, antibody titers of 1:40 or more were observed in 114 of 120 subjects (95.0%) who received the 15-?g dose and in 106 of 119 subjects (89.1%) who received the 30-?g dose. A similar result was observed after the second dose of vaccine. No deaths, serious adverse events, or adverse events of special interest were reported. Local discomfort (e.g., injection-site tenderness or pain) was reported by 56.3% of subjects, and systemic symptoms (e.g., headache) by 53.8% of subjects after each dose. Nearly all events were mild to moderate in intensity.
Conclusions
A single 15-?g dose of 2009 H1N1 vaccine was immunogenic in adults, with mild-to-moderate vaccine-associated reactions. (ClinicalTrials.gov number, NCT00938639 [ClinicalTrials.gov] .)
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<cite cite="http://content.nejm.org/cgi/content/full/361/25/2405?query=TOC">NEJM -- Response to a Monovalent 2009 Influenza A (H1N1) Vaccine</cite>
Michael E. Greenberg, M.D., M.P.H., Michael H. Lai, B.Med.Sc., M.B., B.S., M.Med.Sc., Gunter F. Hartel, M.S., Ph.D., Christine H. Wichems, Ph.D., Charmaine Gittleson, B.Sc., M.B., B.Ch., Jillian Bennet, M.Sc., M.P.H., Gail Dawson, B.Pharm., Wilson Hu, M.D., M.B.A., Connie Leggio, B.Sc., Diane Washington, M.D., and Russell L. Basser, M.B., B.S., M.D., F.R.A.C.P.
ABSTRACT
Background
A novel 2009 influenza A (H1N1) virus is responsible for the first influenza pandemic in 41 years. A safe and effective vaccine is needed. A randomized, observer-blind, parallel-group trial evaluating two doses of an inactivated, split-virus 2009 H1N1 vaccine in healthy adults between the ages of 18 and 64 years is ongoing at a single site in Australia.
Methods
We evaluated the immunogenicity and safety of the vaccine after each of two scheduled doses, administered 21 days apart. A total of 240 subjects, equally divided into two age groups (<50 years and ≥50 years), were enrolled and underwent randomization to receive either 15 ?g or 30 ?g of hemagglutinin antigen by intramuscular injection. We measured antibody titers using hemagglutination-inhibition and microneutralization assays at baseline and 21 days after vaccination. The coprimary immunogenicity end points were the proportion of subjects with antibody titers of 1:40 or more on hemagglutination-inhibition assay, the proportion of subjects with either seroconversion or a significant increase in antibody titer, and the factor increase in the geometric mean titer.
Results
By day 21 after the first dose, antibody titers of 1:40 or more were observed in 114 of 120 subjects (95.0%) who received the 15-?g dose and in 106 of 119 subjects (89.1%) who received the 30-?g dose. A similar result was observed after the second dose of vaccine. No deaths, serious adverse events, or adverse events of special interest were reported. Local discomfort (e.g., injection-site tenderness or pain) was reported by 56.3% of subjects, and systemic symptoms (e.g., headache) by 53.8% of subjects after each dose. Nearly all events were mild to moderate in intensity.
Conclusions
A single 15-?g dose of 2009 H1N1 vaccine was immunogenic in adults, with mild-to-moderate vaccine-associated reactions. (ClinicalTrials.gov number, NCT00938639 [ClinicalTrials.gov] .)
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