The 13-valent pneumococcal vaccine appears to provide very little protection against severe illness from prevailing serotypes in young children, Australian infectious diseases experts have warned.

Their analysis of paediatric hospital admissions data from 2015-18 suggests two-thirds of invasive pneumococcal pneumonia cases are caused by two serotypes — ST3 and ST19A — that are covered by the current vaccine. 

After comparing 779 pneumonia cases with nearly 16,000 matched controls, the UNSW Sydney-led team “failed to identify a strong direct protective effect” with the 13-valent pneumococcal conjugate vaccine (13vPCV). 

Overall, there were 195 cases of confirmed invasive pneumococcal pneumonia, including empyema, most of which were among fully vaccinated children aged 12 months or older.