Keywords:
Case-control; Notification data; Rotavirus; Rotavirus vaccines; Vaccine effectiveness
Abstract:
Objective: Two rotavirus vaccines (RV1 and RV5) were included in the publicly funded National Immunisation Program in Australia from July 2007. The programme in Western Australia initially provided RV1 (at ages 2 and 4 months) and then switched to RV5 (at ages 2, 4 and 6 months) from July 2009. This retrospective case-control study was conducted to assess the effectiveness of rotavirus vaccine against laboratory confirmed and notified cases of rotavirus infection among children aged <5 years. Methods: Case-subjects were identified as vaccine-eligible children (born from 1 May 2007) who were notified as having rotavirus infection during the period 2009–2011. The control group was vaccine-eligible children notified as having Campylobacter or Salmonella infection during the same period. Individual rotavirus immunisation status was ascertained from a population-based immunisation register. Full-dose and partial-dose vaccine effectiveness (VE) were calculated for both vaccines using the adjusted odds ratio (OR) of vaccination for cases versus controls (VE = (1 − OR)*100%). Results: Overall, 282 cases and 883 controls were included. The adjusted VE for a full course of either rotavirus vaccine was 72% (95% CI: 56–82) and 71% (95% CI: 50–84) for partial vaccination (one dose of RV1 or one/two doses of RV5). The VE for a complete 3-dose course of RV5 was 82% (95% CI: 59–92) and for a full 2-dose course of RV1 was 73% (95% CI: 55–83). Conclusions: RV1 and RV5 were both effective in preventing laboratory confirmed and notified rotavirus infections among children aged <5 years. Even incomplete courses of vaccination conferred good protection.