. Author manuscript; available in PMC: 2020 Jul 31.

Published in final edited form as: J Infect Dis. 2019 Jul 31;220(5):820–829. doi: 10.1093/infdis/jiz201

Table 1.

Most Likely Initial Influenza A Virus Subtype Exposure by Birth Cohort

Cohort Name	Birth Years	Cohort Type	Influenza A Subtype(s) Circulating During Birth Years

1918	1918-1922	H1 cohort	A/H1
1933	1933-1937	H1 cohort	A/H1 (significant drift compared with 1918 H1)
1947	1947-1951	H1 cohort	A/H1 (further significant drift compared with 1918 and 1933 H1)
1957	1957-1961	H2 cohort	A/H2
1968	1968-1972	H3 cohort	A/H3
1977	1977-1981	Mixed cohort	A/H1 (similar to 1947 H1), A/H3
1985	1985-1989	Mixed cohort	A/H1 (slightly less similar to 1947 H1), A/H3