The World Health Organization has prequalified a multi-dose vial presentation of the maternal RSV vaccine RSVpreF, known commercially as Abrysvo, marking a milestone that clears the way for wider, more affordable rollout of infant protection against respiratory syncytial virus in lower-income countries. The decision, announced September 9, builds on WHO’s March 2025 prequalification of the vaccine’s single-dose presentation and unlocks a Gavi-backed maternal RSV immunisation programme that had been waiting specifically on this multi-dose approval.
Gavi, the Vaccine Alliance, welcomed the decision, noting that its Board had already approved establishing an RSV maternal vaccine programme for Gavi-supported countries during the Alliance’s 2026-2030 strategic period, but that introduction was conditional on the availability of a WHO-prequalified multi-dose vial.
What WHO Prequalification Actually Means
WHO prequalification is a technical review process that checks whether vaccines and other medical products meet strict international standards for quality, safety, and efficacy. It matters well beyond a regulatory formality: vaccines generally need WHO prequalification before United Nations agencies such as UNICEF can procure them for country programmes, making it a practical gatekeeping step for global vaccine access rather than just a scientific endorsement.
That’s precisely why the multi-dose approval carries outsized weight here. A single-dose vial, discarded after one use, is straightforward from a manufacturing standpoint but costly and logistically demanding to distribute at scale, particularly in settings with limited cold-chain infrastructure. A multi-dose vial spreads packaging, shipping, and storage costs across several doses, making large-scale national introduction meaningfully more feasible for lower-income health systems.
Why RSV Poses Such a Serious Threat to Infants
Respiratory syncytial virus is the leading infectious cause of severe pneumonia in young children worldwide and the second leading cause of infant mortality globally after malaria. Each year, RSV is responsible for an estimated 33 million lower respiratory tract infections, roughly 3.6 million hospitalisations, and more than 100,000 deaths among children under five, according to WHO figures.
The burden of that toll falls overwhelmingly on the world’s poorest regions. More than 97 percent of RSV-related deaths occur in low- and middle-income countries, with the heaviest concentration in sub-Saharan Africa, where many children who die from the virus never reach a health facility at all. Almost half of all RSV deaths occur in infants younger than six months old, precisely the age group maternal immunisation is designed to protect, and precisely the age group least able to receive vaccines directly themselves.
How Maternal Immunisation Protects Newborns
RSVpreF works by vaccinating pregnant women rather than infants directly. WHO recommends administering the vaccine during the third trimester, from 28 weeks of pregnancy onward, allowing the mother’s body to generate protective antibodies that cross the placenta before birth. That transferred immunity shields the infant during the first six months of life, the exact window when RSV poses the greatest danger and before a baby’s own immune system has had time to mature.
In pivotal Phase 3 clinical trials, the vaccine demonstrated 81.8 percent efficacy against severe RSV-associated lower respiratory disease within an infant’s first 90 days of life, with protection remaining at 69.4 percent through six months, according to data reviewed by the European Medicines Agency. Those figures place RSVpreF among the more effective maternal immunisation strategies developed for a single infectious disease target in recent years.
A Deliberate, Two-Year Rollout Strategy
The path to this week’s approval was sequenced deliberately rather than arriving all at once. WHO prequalified RSVpreF’s single-dose presentation in March 2025, and Gavi followed in July 2025 by formally establishing a dedicated maternal RSV vaccine programme, on the explicit condition that a lower-cost, more distributable multi-dose vial would eventually clear WHO’s review. This week’s decision closes that gap, effectively converting a conditional programme into an actionable one.
Development of the multi-dose presentation was supported by the Gates Foundation, reflecting a now-familiar pattern in global vaccine access: a pharmaceutical developer producing the underlying science, philanthropic funding underwriting the specific formulation work needed for equitable global distribution, and multilateral bodies like WHO and Gavi handling the regulatory and financing machinery required to actually get doses into arms in the countries that need them most.
What Comes Next for Countries and Health Systems
“Now that this formulation has received WHO’s quality stamp of approval, we look forward to countries being able to turn those preparations into action, protecting more babies from RSV during their first, most vulnerable months of life.”
— Ignacio Esteban, Senior Policy Manager and incoming Head of Adult & Adolescent Vaccines Portfolio, Gavi
With WHO’s stamp of approval now in place, Gavi-supported countries that had been preparing introduction plans can move from planning into action. WHO currently recommends that countries introduce either the maternal RSV vaccine or nirsevimab, a monoclonal antibody administered directly to infants, as complementary rather than competing strategies for reducing the disease’s toll. Rolling out either option at scale still depends heavily on functioning primary healthcare infrastructure capable of reaching pregnant women and newborns consistently, particularly in rural and underserved regions, a challenge not unlike the one facing broader efforts to expand technology-enabled primary healthcare access in countries such as India.
For now, health officials are framing the multi-dose prequalification as a genuine turning point rather than an incremental regulatory update. As Emily Kobayashi, Director of Vaccine Access at Gavi, put it, the decision “marks an important step towards ensuring that all children, regardless of where they are born, are protected at their very first breath.” The next test will be execution: whether Gavi-supported countries can translate this newly cleared vaccine format into immunisation coverage fast enough to meaningfully cut into RSV’s toll on infant mortality, alongside other maternal and child immunisation efforts like India’s own HPV vaccination programme, which has similarly relied on scaled, affordable vaccine delivery to reach millions of eligible recipients.