Table 2 Comparison of HAI titer increases for seasonal and pandemic IAVs.
ExamsH1H3
USSR/77
(pandemic)
TX/91
(seasonal)
HK/68
(pandemic)
Ala/81
(seasonal)
1–22.443*3.91.5
2–32.91.61.22.5
3–41.41.41.51.0

*TX/91 began circulating between exams 1 and 2.