Description of the study population
| Season 2012–2013 n=794 138 | Season 2013–2014 n=735 136 | Season 2014–2015 n=660 216 | |
|---|---|---|---|
| Age (years) | |||
| 2–3 | 13% (99 855) | 13% (93 161) | 13% (83 241) |
| 4–8 | 31% (248 486) | 31% (232 735) | 32% (211 204) |
| 9–17 | 56% (445 797) | 56% (409 240) | 55% (365 771) |
| Sex | |||
| Male | 51% (406 251) | 51% (375 999) | 51% (337 454) |
| Female | 49% (387 887) | 49% (359 137) | 49% (322 762) |
| Region | |||
| England/North | 14% (114 636) | 14% (102 314) | 12% (76 849) |
| England/Midlands | 18% (147 158) | 16% (121 547) | 15% (100 850) |
| England/South | 32% (253 833) | 32% (232 379) | 32% (215 025) |
| England/London | 12% (94 681) | 13% (97 368) | 13% (83 585) |
| Northern Ireland | 4% (28 189) | 4% (28 090) | 4% (28 204) |
| Scotland | 11% (85 423) | 12% (85 931) | 13% (84 993) |
| Wales | 9% (70 218) | 9% (67 507) | 11% (70 710) |
| High-risk condition | |||
| Chronic respiratory disease (including asthma) | 5% (40 052) | 5% (35 561) | 5% (30 484) |
| Chronic heart disease | 1% (6892) | 1% (6511) | 1% (5943) |
| Chronic kidney disease | <1% (412) | <1% (385) | <1% (356) |
| Chronic liver disease | <1% (232) | <1% (213) | <1% (183) |
| Chronic neurological disease | <1% (3612) | <1% (3384) | <1% (3031) |
| Diabetes | <1% (2052) | <1% (1969) | <1% (1740) |
| Immunosuppression | <1% (1483) | <1% (1427) | <1% (1301) |
| Other high-risk condition | <1% (391) | <1% (298) | <1% (236) |
| Any of the conditions above | 7% (53 475) | 7% (48 254) | 6% (41 940) |