Population characteristics among individuals vaccinated and unvaccinated at the start of the1998/1999 influenza season
| Unvaccinated | Vaccinated | p-value | |
| Respiratory# | 0.006 | ||
| Absent | 152004 (93.9) | 91900 (93.6) | |
| Present | 9952 (6.1) | 6299 (6.4) | |
| Circulatory# | <0.0001 | ||
| Absent | 136499 (84.3) | 81702 (83.2) | |
| Present | 25457 (15.7) | 16497 (16.8) | |
| Diabetes# | 0.78 | ||
| Absent | 154869 (95.6) | 93925 (95.6) | |
| Present | 7087 (4.4) | 4274 (4.4) | |
| Tumour# | 0.39 | ||
| Absent | 154362 (95.3) | 93522 (95.2) | |
| Present | 7594 (4.7) | 4677 (4.8) | |
| Marital status | <0.0001 | ||
| Widow | 49937 (30.8) | 26637 (27.1) | |
| Married | 71372 (44.1) | 53707 (54.7) | |
| Single | 14597 (9.0) | 6162 (6.3) | |
| Divorced | 26050 (16.1) | 11693 (11.9) | |
| Household SES¶ | <0.0001 | ||
| W-C1 | 22800 (14.1) | 20883 (21.3) | |
| W-C2 | 25403 (15.7) | 19669 (20.0) | |
| W-C3 | 24835 (15.3) | 16025 (16.3) | |
| B-C1 | 13842 (8.5) | 6969 (7.1) | |
| B-C2 | 17539 (10.8) | 7913 (8.1) | |
| Retired+ | 35175 (21.7) | 16341 (16.6) | |
| Other | 16825 (10.4) | 9249 (9.4) | |
| Unknown | 5537 (3.4) | 1150 (1.2) | |
| Sex | <0.0001 | ||
| Female | 98847 (61.0) | 57688 (58.7) | |
| Male | 63109 (39.0) | 40511 (41.3) | |
| Age group | <0.0001 | ||
| 65–69 yrs | 41494 (25.6) | 23055 (23.5) | |
| 70–74 yrs | 37477 (23.1) | 25078 (25.5) | |
| 75–79 yrs | 35084 (21.7) | 24253 (24.7) | |
| ≥80 yrs | 47901 (29.6) | 25813 (26.3) | |
| All | 161956 (100.0) | 98199 (100.0) |
Data are presented as n (%). SES: socioeconomic status. #: underlying disease with need for hospital treatment during the period 1995–1998; ¶: white-collar workers are divided into the following groups: W-C1: professionals, W-C2: intermediate nonmanual, and W-C3: assistant nonmanual; blue-collar workers are divided into the following groups: B-C1: skilled manual, and B-C2: unskilled manual; +: this is a mixed group of high age (individuals retiring during or before 1980).