Outbreaks of severe pneumococcal disease in closed settings in the conjugate vaccines era, 2010–2018: A systematic review to inform national guidance in the UK

Introduction: Pneumococcal outbreaks are rare but they still occur, particularly in closed settings usually involving vulnerable groups. We undertook a systematic review to identify strategies for controlling pneumococcal outbreaks since the licensure of higher-valent pneumococcal conjugate vaccines (PCVs). Methods: A systematic literature search was performed for pneumococcal outbreaks published since 2010. A cluster was defined as two or more cases of severe pneumococcal disease in a closed setting within 14 days. Results: Eleven reports were identified, including seven caused by serotypes in both the 13-valent PCV (PCV13) and the 23-valent polysaccharide vaccine (PPV23); two were due to a PCV13-only serotype (6A) and one each by a PCV13-related serotype (6C) and a non-vaccine serotype (15A). Eight reported infection control measures, including reinforcing hand washing, respiratory hygiene and patient cohorting. PPV23 was used in five outbreaks, while PCV13 and both vaccines were used in one outbreak each. Different antibiotics were used for chemoprophylaxis in eight outbreaks. Conclusions: Most pneumococcal outbreaks are currently caused by vaccine-preventable serotypes, and PPV23 is the preferred vaccine in more than half the outbreaks. Early implementation of infection control measures is important, and antibiotic chemoprophylaxis should be considered for high-risk individuals.