Pneumonia hospitalizations of children aged <2 years in Poland before (2013-2016) and after (2017-2018) universal mass vaccination with 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine.

What is the context? Infection with the bacteria Streptococcus pneumoniae is a key cause of pneumonia in children worldwide.Pneumococcal vaccines are available to help prevent this infection.In 2017, a pneumococcal vaccination program was introduced in Poland, free of charge for children aged less than 2 years.The impact of this vaccination program on the incidence of pneumonia hospitalizations is unknown.What is new? This study evaluated the incidence of pneumonia hospitalizations in children following the implementation of the vaccination program (2017-2018) and compared it with the incidence before implementation (2013-2016).The study was carried out in two regional hospitals and included all children aged less than 2 years hospitalized with pneumonia.Pneumonia cases were identified using International Classification of Diseases codes and bacterial cases were confirmed with chest x-rays.During the 2 years after the vaccination program was introduced, we observed:No clear trend in the incidence of bacterial pneumonia confirmed by chest x-ray.A statistically significant decline in the likelihood of developing other types of pneumonia among children eligible for the pneumococcal vaccination program.The incidence of pneumonia was higher in children from the region of Opole and for those who were admitted to hospital in winter and at a younger age.What is the impact? Pneumococcal vaccination might reduce the number of pneumonia hospitalizations. However, more research is needed to confirm these results.