Table 3.
Cross-Reactive HI Antibodies to H3N2v Viruses, by Age Group, in US Human Serum Samples Collected in 2010
| Age Group in 2010, y |
Birth Years | Subjects, No. | HI Titer ≥40 (95% CI), % | HI GMT (95% CI) | ||
|---|---|---|---|---|---|---|
| OH/13/12 | IN/6/13 | OH/13/12 | IN/6/13 | |||
| 6–9 | 2001–2004 | 48 | 17 (6–27) | 13 (3–22) | 9 (7–11)a | 10 (8–13)a |
| 10–19 | 1991–2000 | 188 | 62 (55–69)b | 82 (77–88)b | 51 (41–64)b | 90 (76–108)b |
| 20–29 | 1981–1990 | 121 | 88 (83–94) | 90 (85–95) | 105 (84–131) | 97 (81–117) |
| 30–39 | 1971–1980 | 121 | 74 (66–81)b | 55 (47–64)b | 49 (41–58)b | 32 (27–39)b |
| 40–49 | 1961–1970 | 125 | 34 (25–42) | 30 (22–38) | 18 (15–22) | 18 (15–22) |
| 50–59 | 1951–1960 | 99 | 35 (26–45) | 35 (26–45) | 19 (15–24) | 20 (15–25) |
| 60–69 | 1941–1950 | 118 | 44 (35–53) | 48 (39–57) | 25 (20–32) | 27 (21–35) |
| 70–79 | 1931–1940 | 108 | 52 (42–61) | 50 (41–59) | 32 (25–41) | 28 (22–36) |
| ≥80 | 1908–1930 | 79 | 46 (35–57) | 39 (28–50) | 23 (17–31) | 20 (15–27) |
| All ages | 1908–2004 | 1007 | 54 (51–57) | 55 (52–58) | 33 (31–36) | 35 (32–38) |
Abbreviations: CI, confidence interval; GMT, geometric mean titer; H3N2v, influenza A(H3N2) variant; HI, hemagglutination-inhibition; IN/6/13, A/Indiana/06/2013; OH/13/12, A/Ohio/13/2012.
a
P = .04 for difference in HI GMT between OH/13/12 and IN/6/13.
b
P < .01 for difference in seroprevalence or HI GMT between OH/13/12 and IN/6/13.