A reduction in all-cause acute otitis media (AOM) of 22% was observed in children after vaccination with 10-valent pneumococcal conjugate vaccine (PCV10), according to research published in Clinical Infectious Diseases.
The PCV10 was introduced in Iceland in 2011, and a whole-population study used all primary care visits resulting from AOM in children younger than 3 years to evaluate its effect on AOM.
Birth cohorts were grouped as vaccine noneligible (2005-2010) or vaccine eligible (2011-2015). In total, 53,150 children were included with 140,912 person-years of follow-up and 58,794 AOM episodes.
Significant differences in crude incidence rates and episodes per child were observed between the vaccine noneligible and eligible groups: 43 vs 38 episodes per 100 person-years and 1.61 vs 1.37 episodes per child, respectively. The vaccine effect on all-cause AOM was 22% (95% CI, 12%-31%), which was mediated through its effect on the first (hazard ratio [HR], 0.84; 95% CI, 0.82-0.86) and second (HR 0.95; 95% CI, 0.93-0.98) episodes. A 40% reduction in crude incidence rate (95% CI, 31%-49%) in children too young to be vaccinated provided evidence of herd protection.
Study strengths are the use of 11 consecutive birth cohorts from a whole-country population registry and a broad definition of AOM. Plus, the individual nature of the data allowed for data collection on a single child throughout multiple visits. The observational nature, however, was a limitation because the possibility that coding practices or healthcare-seeking behavior changed during the study period could not be excluded. It is also possible that an increase in private physician visits is another bias, as these could not be included because of differences in coding practices; however, the investigators believe this would not have affected results significantly.
Therefore, it is safe to conclude that there was a vaccine effect of PCV10 on all-cause AOM and evidence of a herd effect on the population.
Sigurðsson S, Eythorsson E, Hrafnkelsson B, Erlendsdóttir H, Kristinsson KG, Haraldsson Á. Reduction in all-cause acute otitis media in children less than three years of age in primary care following pneumococcal vaccination with PHiD-CV10: A whole population study [published online March 30, 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy233