A systematic review of invasive pneumococcal disease vaccine failures and breakthrough with higher-valency pneumococcal conjugate vaccines in children.

INTRODUCTION: The pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV/PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) protect against vaccine-serotype invasive pneumococcal disease (VT IPD). However, VT IPD can still occur in fully or partially vaccinated children (vaccine failure or breakthrough). We performed a systematic review of vaccine failures and breakthrough IPD with PCV10 and PCV13 in ≤5-year-olds. AREAS COVERED: We searched Scopus/Medline/EMBASE to retrieve articles/abstracts published between 1/2008-7/2019. We excluded reports only including data from ≥6-year-olds, exclusively assessing PCV7-vaccinated children or children with comorbidities. Twenty-six reports (20 PCV13, 1 PCV10, 5 both), covering studies with various designs in six continents, using different schedules, were included. Collectively, they reported 469 VT IPD cases classified as vaccine failures and 403 as breakthrough. Vaccine failure and breakthrough rates were low: 8.4% and 9.3%, respectively, of all IPD in vaccinated children, consistent with the vaccines' high effectiveness. The main serotypes associated with vaccine failure/breakthrough were 19A, 3 and 19F for PCV13 and 14, 6B and vaccine-related 19A and 6A for PCV10. EXPERT OPINION: As we move to vaccines with more serotypes, it is not only important to consider which serotypes are added, but also monitor and address incomplete protection against specific serotypes.