Table 2 The demographic information for the participants in different influenza seasons included in this study
From: Investigation of CD4 and CD8 T cell-mediated protection against influenza A virus in a cohort study
Year | 2009 | 2010 | 2011 | 2012 | 2013 | 2013 |
|---|---|---|---|---|---|---|
Influenza epidemic type/subtype | pH1N1 (pandemic) | H3N2 (epidemic) | pH1N1 (epidemic) | H3N2 (epidemic) | pH1N1 (epidemic) | H3N2 (epidemic) |
Number of individuals | 114 | 135 | 164 | 161 | 196 | 195 |
Age group | ||||||
 < 18 years | 49 (43%) | 47 (35%) | 69 (42%) | 68 (42%) | 81 (41%) | 81 (42%) |
 18–50 years | 58 (51%) | 75 (56%) | 80 (49%) | 76 (47%) | 94 (48%) | 93 (48%) |
 ≥ 51 years | 7 (6%) | 13 (10%) | 15 (9%) | 17 (11%) | 21 (11%) | 21 (11%) |
Pre-season HAI titer < 40 against corresponding epidemic strain | 114 (100%) | 94 (70%) | 118 (72%) | 101 (63%) | 148 (76%) | 128 (66%) |
Number of Infections by age groups | ||||||
 < 18 years | 35 (31%) | 6 (4%) | 10 (6%) | 19 (12%) | 6 (3%) | 6 (3%) |
 18–50 years | 19 (17%) | 9 (7%) | 7 (4%) | 17 (11%) | 7 (4%) | 4 (2%) |
 ≥ 51 years | 1 (1%) | 3 (2%) | 2 (1%) | 3 (2%) | 1 (1%) | 1 (1%) |