Single Dosage Effectiveness

Results: By day 21 after vaccination, antibody titers of 1:40 or more were observed in 116 of 120 subjects (96.7%) who received the 15-µg dose and in 112 of 120 subjects (93.3%) who received the 30-µg dose. 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 46.3% of subjects, and systemic symptoms (e.g.,
headache) by 45.0% of subjects. Nearly all events were mild to moderate in intensity.

Conclusions A single 15-µg dose of 2009 H1N1 vaccine was immunogenic in adults, with mild-to-moderate vaccine-associated reactions.
(ClinicalTrials.gov number, NCT00938639 [ClinicalTrials.gov] .)