A nationwide study on the impact of pneumococcal conjugate vaccination on antibiotic use and ventilation tube insertion in Denmark 2000-2014.

Introduction of Pneumococcal Conjugated Vaccines (PCV) in national immunization programs have been successful in reducing the number of invasive and lower respiratory pneumococcal infections. The impact of the vaccines on upper respiratory infections caused by pneumococci is less clear although these account for most pneumococcal infections. In this study, we used likely proxies for respiratory infections in children, such as antibiotic use and ventilation tube insertions (VTI), to estimate the impact of the vaccine on a national level. The study was designed as a population-based retrospective observational study, comparing trends in the incidence rate of antibiotic prescriptions and VTIs in the period 2000-2014, where PCV7 was introduced in 2007 and PCV13 in 2010. The introduction of PCV7 and PCV13 correlated with changes in the incidence rate from an almost steady increase in prescription of antibiotics in the pre-PCV period to a decreasing incidence for all children age 0-15years. The 2.4 DDD per person year in 2014 was at almost the same level of antibiotic use as in 2000 at 2.3 DDD per person year. Similar patterns were observed in the mostly vaccinated age groups below 5years of age. For VTI we observed a decreasing incidence rate in the years following introduction of PCV13 ending with a slightly higher incidence at 35 per 1000 person years in 2014 compared to 31 in year 2000. We conclude that the steady increase in antibiotic use and VTI in the pre-PCV period have been partially reversed to near year 2000 levels after the introduction of PCV. This indicates that implementation of pneumococcal vaccines in the Childhood Vaccination Programme has likely reduced the incidence of upper respiratory diseases due to pneumococci in Denmark.