Editorial Commentary: A Tale of 2 Pneumococcal Vaccines

Abstract

Pneumonia isthe leading infectious cause of death in all age groups. After 4 decades with just a single bacterial vaccine to prevent the disease, we now have conjugate pneumococcal vaccines licensed across most age groups to complement the 23-valent pneumococcal polysaccharide vaccine (PPV23),which has beenthe mainstay of efforts to protect persons aged >2 years from pneumococcal infections. Two articles in the current issue of Clinical Infectious Diseases from authors in adjacent European countries advance our knowledge on the effectiveness of these vaccines, although the clarity of their messages are starkly different. From Angoulvant et al in France [1], we see the extraordinary effectiveness of the 13-valent pneumococcal conjugate vaccine (PCV13) just a year after introduction when given to infants without any catch-up program for older children. In an observational effectiveness study dedicated to the late Edouard Bingen, a giant in pediatric microbiology in France, his colleagues used PCV13 introduction to illustrate vaccine effectiveness and to provide insight into the pneumococcal etiology of community-acquired pneumonia (CAP) and empyema in children. Their article contains at least 5 interesting messages. First, they observed a rapid (within a year) reduction of 31% among nearly 2000 radiographically-confirmed pneumonias in the target age group of children <2 years seen in the emergency rooms of 8 hospitals across France. This study illustrates that surveillance of radiographicallyconfirmed pneumonia in a limited number of hospitals is a useful measure of PCV effectiveness, beyond surveillance for invasive pneumococcal disease (IPD) alone. The impact of PCV13 on IPD was recently demonstrated in a similar study in 8 US hospitals [2]. The observed reduction of several hundred episodes of radiographically-confirmed pneumonia in the French study contrasts with the small (4%) yield of pneumococcal cultures from blood from these patients and makes the argument that the evaluation of PCV impact may be possible in developing countries without microbiology facilities if radiography can be provided and performed in an adequate fashion with surveillance inplaceatemergency rooms of large urban hospitals.