Table 3

Comparison of immunity against A/Brisbane/59/2007 (H1N1) for the seasonal influenza vaccine recipients and nonrecipients pre- and postvaccination at 1 month after influenza A/H1N1 2009 vaccinationa

ParameterSeasonal influenza vaccine recipients (n = 209)Seasonal influenza vaccine nonrecipients (n = 80)P value
GMT (95% CI)
    Prevaccination62.3 (54.4–71.3)37.9 (27.5–52.1)<.01
    Postvaccination68.6 (62.3–75.5)78.6 (64.2–96.1)0.23
GMT ratio (95% CI)1.1 (1.0–1.1)2.1 (1.8–2.3)0.01
  • a A/Brisbane/59/2007 (H1N1) is the 2009-2010 seasonal influenza vaccine strain. GMT, geometric mean titer; CI, confidence interval.