Indirect Impact of Ten-valent Pneumococcal Conjugate Vaccine Program on Reducing Antimicrobial Use and Tympanostomy Tube Placements in Finland

Background: Acute otitis media (AOM) is the most common reason for antimicrobial use, and tympanostomy tube placement (TTP) is the most common reason for surgery requiring general anesthesia in children. Ten-valent pneumococcal conjugate vaccine (PCV10) was introduced in Finland in 2010 for infants. We evaluated the indirect impact of PCV10 on these surrogate otitis outcomes in unvaccinated children. Methods: Using before-after design, unvaccinated children ineligible for National Vaccination Program (born January 2006 to May 2010) were followed-up during 2012-2016 (target cohort, age 1.5-7 years). The target cohort was compared with an age- and season-matched unvaccinated reference cohort (born January 2000 to May 2004) during 2006-2010. Antimicrobial purchase data were obtained from the Social Insurance Institution of Finland benefits register. We assessed the relative reduction by generalized Cox regression for outpatient purchases of antibiotics recommended for treatment of AOM in the Finnish guidelines. Data on all TTP procedures were obtained from national hospital discharge register and Social Insurance Institution benefits register. Results: The rate of outpatient purchases of antimicrobials recommended for AOM was 51 in the unvaccinated reference cohort and 44/100 person-years in the unvaccinated target cohort; relative rate reduction was 14.7% [95% confidence interval: 14.0-15.3] and absolute rate reduction 7/100 person-years. The rates of TTP in the reference and target cohorts were 1.66/100 and 1.61/100 person-years, respectively. The relative rate reduction was 3.6% (0.7-6.5). Conclusions: Antimicrobial use and TTP procedures reduced in unvaccinated children after PCV10 introduction in infants. These indirect effects contribute to the savings in health care resource use for otitis and may also help in combating antimicrobial resistance.