As infection with Streptococcus pneumoniae is an important cause of pneumonia in children, the World Health Organization recommends childhood pneumococcal conjugate vaccines (PCVs). In January 2017, PCV universal mass vaccination (UMV) was introduced in Poland for children aged <2 years. The objective of this study was to estimate and describe the trends in the incidences of various types of pneumonia hospitalizations in Poland before (2013-2016) and after (2017-2018) introduction of the UMV program. The study was conducted at the regional hospitals of Opole and Bialystok and included all hospitalized children aged <2 years with a primary or secondary diagnosis of pneumonia in their electronic medical records. Pneumonia diagnoses were identified based on International Classification of Diseases 10th revision (ICD-10) codes for bacterial, viral, and other/unknown-cause pneumonias. The effect of the implementation of PCV UMV was modeled via an inferential multivariate model. Among 4,168 children included in the study, 64.3% were admitted before PCV UMV. The number of radiograph-confirmed likely bacterial pneumonia cases varied between 55 and 176 cases per 100,000 person-years, and no trend was observed over time. However, inferential modeling showed statistically significant decreasing trends in the incidence rates of bacterial-coded pneumonia (28.48%), viral-coded pneumonia (35.36%), all-cause pneumonia (24.60%), and radiograph-confirmed likely non-bacterial pneumonia (24.98%) among children eligible for UMV. This might be the first indication of the impact of the PCV UMV program in Poland.
Keywords: ICD-10; PHiD-CV; Pneumonia; Poland; chest radiograph; incidence; pneumococcal conjugate vaccine; universal mass vaccination.
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.