Table 4. Incidence of pertussis in household contacts by characteristic, Catalonia and Navarre, Spain, 2012–13 (n = 2,852).
| Characteristic of household contact |
Incidence of pertussis
among contacts |
Odds ratio | 95% CI | |
|---|---|---|---|---|
| % | n/total | |||
| Sex | ||||
| Female | 15.9 | 241/1,512 | 1.0 | 0.8 to 1.2 |
| Male | 16.3 | 218/1,340 | Reference | |
| Age in years | ||||
| < 1 | 69.3 | 104/150 | 24.6 | 16.2 to 37.4 |
| 1 | 44.8 | 26/58 | 8.8 | 5.0 to 15.6 |
| 2–3 | 25.0 | 33/132 | 3.6 | 2.3 to 5.7 |
| 4–6 | 21.5 | 43/200 | 3.0 | 2.0 to 4.5 |
| 7–10 | 19.5 | 43/221 | 2.6 | 1.7 to 3.9 |
| 11–18 | 19.1 | 40/209 | 2.6 | 1.7 to 3.9 |
| 19–40 | 9.6 | 93/967 | 1.2 | 0.8 to 1.6 |
| > 40 | 8.4 | 77/915 | Reference | |
| Household contacts | ||||
| Cohabitants | 16.5 | 336/2034 | 1.1 | 0.9 to 1.4 |
| Non-cohabitants | 15.0 | 123/818 | Reference | |
| Relationship with primary case | ||||
| Mother | 8.3 | 46/556 | 1.8 | 1.0 to 3.4 |
| Father | 8.8 | 45/510 | 2.0 | 1.1 to 3.7 |
| Sibling | 25.7 | 133/518 | 7.2 | 4.2 to 12.6 |
| Grandparent | 4.5 | 15/330 | Reference | |
| Child | 61.2 | 85/139 | 33.0 | 17.7 to 61.5 |
| Partner | 16.0 | 16/100 | 4.0 | 1.9 to 8.4 |
| Othera | 17.0 | 119/699 | 4.3 | 2.5 to 7.5 |
| Vaccination statusb (≤ 18 years) | ||||
| Fully vaccinated | 23.8 | 138/581 | 0.11 | 0.07 to 0.17 |
| Undervaccinated | 52.9 | 64/121 | 0.38 | 0.22 to 0.68 |
| Unvaccinated | 74.5 | 76/102 | Reference | |
| Received chemoprophylaxisc | ||||
| Yes | 9.9 | 226/2,284 | 0.47 | 0.35 to 0.62 |
| No | 19.0 | 77/406 | Reference | |
CI: confidence interval.
a Caregiver, family friend or neighbour.
b Vaccination status was categorised as fully vaccinated (≥ 4 doses of vaccine), undervaccinated (< 4 doses) or unvaccinated (no dose).
c Azithromycin was used.