Pneumonia with empyema among children in the first five years of high coverage with 13-valent pneumococcal conjugate vaccine

Background: Parapneumonic effusions in children are usually associated with pneumococcal infections. In Greece, the 7-valent pneumococcal conjugate vaccine was replaced by higher-valent pneumococcal conjugate vaccines (PCVs); 10-valent was introduced in May 2009 and 13-valent (PCV13) in June 2010. Since July 2010, PCV13 has been the most commonly used PCV. In a study conducted at the University General Hospital of Larissa, Central Greece, from January 2012 to January 2016, 85.7% of children born after the implementation of PCV13 and aged 24-59 months had received the complete series (3+1 immunization schedule) of PCV13.Methods: We studied all paediatric community-acquired pneumonia cases with empyema hospitalized at the University General Hospital of Larissa from January 2008 to January 2016.Results: There were 30 cases of parapneumonic empyema. Among 27 empyema cases of known aetiology, 19 (70.4%) were due to Streptococcus pneumoniae (identifiable serotypes 3, 19A, 7F, and 9N/L). After September 2011, no more cases caused by serotypes 7F and 19A were observed, whereas serotype 3 emerged as the predominant pathogen of pneumococcal empyema (9 of 11 cases). Serotype 3 continued to cause empyema despite vaccination with PCV13 either fully with a 3+1 schedule (n=3) or with one booster dose at the age of 21 months (n=1).Conclusion: In Central Greece during the first five years of high coverage with PCV13, serotype 3 was the only PCV13 serotype that clearly persisted in children with empyema.