title: Indirect effects of a 7 year PCV7/PCV13 mass vaccination program in children on the incidence of pneumonia among adults: a comparative study based on two Polish cities.
abstract: OBJECTIVE
  In 2006 the city of Kielce, Poland, introduced a mandatory PCV7 (replaced by PCV13 in 2011) vaccination program against S. pneumoanie for all children under 2 years old. At that time, the neighboring city of Ostrowiec Świętokrzyski had no such large-scale vaccination program in place. This created an opportunity to observe the results of the vaccination by comparing the incidence of pneumonia in these two cities. The aim of this study was to analyze how the incidence of pneumonia among adults was indirectly affected by the PCV7/PCV13 vaccination program in children during the 7 year follow-up period.
  
  
  METHODS
  We performed a retrospective study. PCV7/PCV13 vaccinations were delivered according to a 2 + 1 schedule. The vaccination rate in the analyzed period amounted to almost 99%. The following age groups were analyzed: 30-49, 50-64 and 65+. The Cochran-Armitage test was used to investigate the significance of the observed trend in pneumonia morbidity. The significance of deviations from a linear trend was also tested. In addition, the importance of the trend (in the case of deviations from linearity) was confirmed with the use of the Mantel test.
  
  
  RESULTS
  In the 65+ age group there was a decrease of 66.5% in the incidence of diagnosed pneumonia (p < 0.0001). This was followed by smaller, but statistically significant, declines in the other age groups: 30.75% in the 30-49 age group (p = 0.001) and 56.8% in the 50-64 age group (p < 0.0001). This decreasing trend continued for seven consecutive years of observation. In addition, we demonstrated a statistically significant higher rate of pneumonia in all age groups in the City of Ostrowiec Świętokrzyski.
  
  
  CONCLUSIONS
  The results clearly indicate that the indirect effectiveness of the PCV7/PCV13 vaccine program, performed according to the 2 + 1 schedule and applied in Kielce, Poland, is statistically significant.
authors.affiliation: a a NZOZ Promed Kielce , Poland.
authors.forename: M
authors.initials: M
authors.lastname: Patrzałek
authors.affiliation: b b Department of Paediatric Gastroenterology and Nutrition , Medical University of Warsaw , Poland.
authors.forename: M
authors.initials: M
authors.lastname: Kotowska
authors.affiliation: c c National Institute of Public Health, National Institute of Hygiene , Warsaw , Poland.
authors.forename: P
authors.initials: P
authors.lastname: Goryński
authors.affiliation: b b Department of Paediatric Gastroenterology and Nutrition , Medical University of Warsaw , Poland.
authors.forename: P
authors.initials: P
authors.lastname: Albrecht
mesh_terms: D000328:Adult; D000368:Aged; D002947:Cities; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage*; D006801:Humans; D015994:Incidence; D032541:Mass Vaccination; D008875:Middle Aged; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011014:Pneumonia / Q000453:epidemiology*; D011044:Poland / Q000453:epidemiology; D012189:Retrospective Studies; D014611:Vaccination
chemical_list: C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines
keywords: 13-valent conjugate pneumococcal vaccine; Adults; Children; Heptavalent conjugate pneumococcal vaccine; Herd immunity; Pneumonia