Table I.
Demographic and Risk Factor Characteristics of Study Participants With Influenza Infection, by Subtype
| Variable | Description | A/H1N1 | A/H3N2 | B |
|---|---|---|---|---|
| Age | 18–24 y | 17 (25) | 9 (13) | 4 (21) |
| 25–34 y | 28 (41) | 34 (49) | 4 (21) | |
| 35+ y | 24 (35) | 26 (38) | 11 (58) | |
| Sex | Male | 40 (58) | 41 (59) | 14 (74) |
| Site | MAMC | 8 (12) | 7 (10) | 3 (16) |
| NMCP | 11 (16) | 11 (16) | 4 (21) | |
| NMCSD | 28 (41) | 30 (43) | 11 (58) | |
| SAMMC | 20 (29) | 18 (26) | 1 (5) | |
| WRNMMC | 2 (3) | 3 (4) | 0 (0) | |
| Race | White | 41 (59) | 26 (38) | 11 (58) |
| Black | 11 (16) | 14 (20) | 2 (11) | |
| Hispanic | 12 (17) | 21 (30) | 5 (26) | |
| Unknown/other | 5 (7) | 8 (12) | 1 (5) | |
| >High school education | 39 (57) | 43 (62) | 9 (47) | |
| Military status*,+ | Active duty | 42 (61) | 50 (72) | 8 (42) |
| Dependent | 17 (25) | 16 (23) | 5 (26) | |
| Retired | 10 (14) | 3 (4) | 6 (32) | |
| Season*,^ | 2009/10 | 8 (12) | 0 (0) | 0 (0) |
| 2010/11 | 22 (32) | 25 (36) | 5 (26) | |
| 2011/12 | 7 (10) | 9 (13) | 3 (16) | |
| 2012/13 | 5 (7) | 31 (45) | 6 (32) | |
| 2013/14 | 27 (39) | 4 (6) | 5 (26) | |
| Vaccinated in past 8 m | 49 (71) | 52 (75) | 12 (63) | |
| Vaccinated in past 8 m – active military | 40 (98) | 45 (88) | 7 (88) |
* P < 0.05 across all 3 types.
^ P < 0.05 for H1 vs. H3.
+ P < 0.05 for A vs. B.
MAMC, Madigan Army Medical Center; NMCP, Naval Medical Center Portsmouth; NMCSD, Naval Medical Center San Diego; SAMMC, San Antonio Military Medical Center; WRNMMC, Walter Reed National Military Medical Center.