Burden of invasive pneumococcal disease

TO THE EDITOR—We read with interest the article by Kent et al [1]. The authors note that the burden of invasive pneumococcal disease (IPD) in UK infants aged <1 year is substantial and that the incidence of IPD in this age group increased over the study period (2013–2016). Although the majority of IPD cases (369/454, 71.4%) were due to non–13-valent pneumococcal conjugate vaccine (PCV13) serotypes, disease also was caused by PCV13 (vaccine type [VT]) serotypes (85/454, 16.4%), with a limited reduction in VT IPD from 36 cases in 2013 to 28 cases in 2016. Serotype 3 was the most common VT serotype identified; however, 9 other VT (plus 6C) serotypes also caused infant IPD, in particular, 19A, 7F, and 19F. This suggests ongoing transmission of VT pneumococci with risk of disease to children with insufficient immunity. While premature infants and those with clinical risk factors for IPD were most at risk of developing IPD (13.0% and 28.6%, respectively), full-term infants with no identified risk factors were also at risk.