Volume 28, Number 5—May 2022
Research
Determining Existing Human Population Immunity as Part of Assessing Influenza Pandemic Risk
Jonathan Tin Lai Cheung, Tim K. Tsang, Hui-ling Yen, Ranawaka A.P.M. Perera, Chris Ka Pun Mok, Yong Ping Lin, Benjamin J. Cowling, and Malik Peiris
Table 3
Seroprevalence and geometric mean titers of hemagglutination inhibition antibodies to historical H2 and H1 pandemic viruses based on age group among persons in Hong Kong, China*
| Age group, y | A/California/4/2009 (H1N1pdm09)† |
A/Singapore/1/1957 (H2N2pdm1957) |
|||
|---|---|---|---|---|---|
| Seroprevalence† (%), n = 600 | GMT (95% CI) | Seroprevalence† (%), n = 295 | GMT (95% CI) | ||
| 0–10 | 0/72 (0) | 6 (6–7) | 0/24 (0) | 5 (5–6) | |
| 11–20 | 10/107 (9.3) | 8 (7–9) | 0/38 (0) | 5 (5–6) | |
| 21–30 | 3/46 (6.5) | 6 (5–8) | 0/39 (0) | 5 | |
| 31–40 | 5/39 (12.8) | 8 (5–11) | 0/37 (0) | 5 (5–6) | |
| 41–50 | 9/125 (7.2) | 6 (5–7) | 13/38 (34.2) | 15 (9–24) | |
| 51–60 | 6/131 (4.6) | 6 (5–6) | 40/40 (100) | 243 (172–342) | |
| 61–70 | 1/54 (1.9) | 6 (5–7) | 40/40 (100) | 320 (249–411) | |
| >70 | 3/26 (11.5) | 7 (5–10) | 36/39 (92.3) | 136 (89–209) | |
*GMT, geometric mean titer. †Proportion of persons with hemagglutination inhibition antibody titers >1:40.
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