A new three-dose vial presentation of the maternal RSV vaccine received prequalification from the World Health Organization (WHO) on Wednesday, unlocking large-scale distribution across lower-income countries. The decision enables global health alliances to introduce affordable immunisation during pregnancy, protecting newborns from severe respiratory disease.

Respiratory syncytial virus (RSV) remains the second leading cause of infant mortality globally after malaria, claiming over 100,000 lives annually among children under five, according to the WHO. More than 97% of these deaths occur in low- and middle-income countries with a particularly high burden in sub-Saharan Africa, where healthcare facilities often lack specialised respiratory care.

Pregnant women vaccinated in their third trimester with the multi-dose vial, marketed as Abrysvo by Pfizer, transfer protective antibodies across the placenta, shielding infants throughout their first six months of life.

The vaccine showed high efficacy in global clinical trials across high- and low-income settings, according to the European Medicines Agency (EMA). In pivotal Phase 3 clinical trials, it demonstrated 81.8% efficacy against severe RSV-associated lower respiratory disease in the infant’s first 90 days, maintaining 69.4% efficacy through six months.

Gavi, the Vaccine Alliance, welcomed the WHO’s decision on Wednesday and announced it would expand access for lower-income countries.

“The WHO prequalification of a multi-dose RSV maternal vaccine marks an important step towards ensuring that all children, regardless of where they are born, are protected at their very first breath,” said Emily Kobayashi, Director of Vaccine Programmes at Gavi.

Expanding RSV vaccine access in low-income settings

Building on Gavi’s board approval to establish a dedicated maternal programme for its 2026–2030 strategic period, the Vaccine Alliance said that eligible low-income countries can now apply for funding to integrate maternal immunisation into routine healthcare systems.

The RSV vaccine was developed with support from the Gates Foundation and reduces logistical barriers and cold-chain costs for developing health systems by packing multiple doses into a single vial. While monoclonal antibodies offer direct passive protection to newborns, maternal vaccination provides an alternative route by conferring immunity before birth, broadening global prevention options alongside existing antibody therapies.

Ensuring seamless rollout is critical. Even in high-income regions like Europe, implementation of RSV prevention has faced hurdles due to delivery gaps and fragmented funding – a challenge global health officials hope Gavi’s centralized support will prevent in lower-income settings.

Monitoring safety and birth outcomes

Regulatory bodies, including the EMA, authorised Abrysvo after concluding that its protective benefits far outweigh potential risks. Post-authorization surveillance in the United States confirmed that preterm birth rates among vaccinated mothers showed no statistically significant increase and remained within expected background levels.

Routine post-marketing surveillance programmes in Europe and the United States continue to track real-world health outcomes to ensure standard safety monitoring across diverse populations.

See related story:

Immunising for Prosperity: Why Europe Must Treat RSV and Pneumococcal Jabs an Economic Imperative

Image Credits: USAID/Ghana via Flickr.