Why is Flanders still using a pneumococcal vaccine that misses the strain killing children?

Four young children in Flanders have died since the beginning of 2025 after contracting invasive pneumococcal disease caused by serotype 12F, the Flemish Department of Care confirmed on 11 August. Two babies died in 2025 and two more young children in the first half of 2026, according to reporting by HLN and VRT NWS. The cases expose an increasingly difficult gap in Flemish preventive care: children routinely receive the 13-valent PCV13 vaccine free of charge, but 12F is among the additional strains covered by the newer PCV20 vaccine.

For families in Flanders, the immediate question is not whether pneumococcal vaccination works. PCV13 still protects against 13 dangerous bacterial variants and remains part of the basic schedule administered through Opgroeien’s Kind en Gezin

The epidemiological warning has been building. Sciensano’s National Reference Centre found that 12F was Belgium’s most prevalent invasive pneumococcal serotype in the first half of 2025, accounting for 18.9% of typed cases across all ages, 24.1% among children under two and almost 30% among those aged two to 17. Its 2024 surveillance report had already identified the emergence of 12F amid a record 2,120 confirmed invasive infections nationally. VRT NWS reported in March 2025 that the totals for December 2024 and January 2025 were the highest recorded since surveillance began.

Belgium’s Superior Health Council responded in April 2025 by recommending PCV20 for routine childhood vaccination. Its framing is precautionary: the 20-valent product covers more of the serotypes appearing in Belgian surveillance and should be given in a four-dose, or 3+1, schedule to strengthen protection from infancy. The European Medicines Agency has authorised Prevenar 20 for children in the European Union and concluded that its benefits outweigh its risks. This is therefore not a case of a product awaiting European clearance.

The Flemish administration takes a more procedural position. The Department of Care says it is evaluating the broader vaccine, while its procurement records show a tender for PCV20 supplies for the Flemish immunisation programme from 2027. A switch is more complicated than replacing one vial with another: the council’s preferred PCV20 schedule requires four doses, compared with the three-dose PCV13 schedule now used in Flanders, affecting purchasing, appointments, logistics and programme costs. Those constraints explain why implementation requires planning, but they do not settle whether waiting until 2027 is proportionate after four deaths linked to a covered serotype. Flemish Welfare Minister Caroline Gennez has political responsibility for the health-prevention portfolio; no detailed ministerial timetable explaining whether the transition can be accelerated was identified in the official material reviewed for this article.

The broader lesson is one familiar to vaccination programmes worldwide. Once vaccines suppress targeted pneumococcal strains, other serotypes can occupy more of the ecological space—a process known as serotype replacement. Belgian research covering 543 children with invasive disease between 2019 and 2024 found that many infections were already caused by types outside PCV13, although researchers also cautioned that real-world effectiveness against every additional PCV20 serotype remains uncertain. What happens next depends on the Department of Care’s evaluation and procurement decision. Parents should continue the existing schedule rather than delay vaccination, while asking their doctor about individual circumstances. The unanswered policy question is narrower and urgent: whether Flanders can introduce broader protection before the planned 2027 supply cycle.