Increased paediatric hospitalizations for empyema in Australia after introduction of the 7-valent pneumococcal conjugate vaccine

Although the PCV7 has substantially reduced the rates of invasive pneumococcal disease, reports from around the world suggest that the incidence of empyema in children has increased following the introduction of the PCV7. The reasons for this are not entirely clear, but virulent serotypes not covered by the PCV7 may have emerged as a result of the selective pressure applied by the vaccine. Most cases of empyema among Australian children are caused by serotypes 1, 3 and 19A, which are believed to be particularly virulent and more likely to invade the pleural cavity. The reported increase in serotypes 1, 3 and 19A among invasive isolates might explain the increase in empyema but not in pneumonia per se. On the other hand, an increase in the incidence of empyema was observed in some studies before the introduction of the PCV7. This suggests that the observed association between the introduction of the PCV7 and the rise in empyema incidence may be coincidental.

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