Rotavirus vaccination impact, Ireland, implications for vaccine confidence and screening

Rotavirus vaccine efficacy is well established. However, it is important to consistently demonstrate the positive impact of vaccination programmes in order to optimize uptake rates and combat vaccine hesitancy.

Routine data were used to examine rotavirus vaccine effectiveness in Ireland, including changes in age-specific crude incidence rates (CIRs), hospitalizations and hospital length of stay. National intussusception incidence was interrogated. Vaccination status of vaccine-eligible cases of rotavirus infection was determined.

Nationally, a reduction in the CIR of rotavirus infection of 77.2% [95% confidence interval (CI) 57.8-88.5%, P<0.001] was observed post-inclusion of the rotavirus vaccine in the primary immunization schedule. A decrease in hospitalizations of 85.5% (95% CI 79.3-90.2%, P<0.001), 86.5% (95% CI 82.9-89.4%, P<0.001) and 78.5% (95% CI 74.7-81.9%, P<0.001) was observed in children aged <1, <2 and <5 years, respectively. Most hospitalizations occurred in infants too young to have been vaccinated. There was no significant difference in median length of stay for children hospitalized with rotavirus infection. Decreased CIRs and hospitalization rates in unvaccinated children aged between 2 and 5 years suggest community immunity. Vaccine non-protection was 0.13%. No increase in the national CIR of intussusception was observed.

Inclusion of the rotavirus vaccine in the Irish primary immunization schedule has resulted in a significant reduction in the burden of rotavirus infection. However, vaccine hesitancy remains a concern. With new vaccination programmes, risk of vaccine harms should be considered and mitigated in order to protect individuals and the integrity of the programme.