Pan American Health Organization · 1st edition, 2026 · 34 pages
PAHO guidance on RSVpreF maternal vaccine, nirsevimab and clesrovimab for preventing RSV disease in infants, for immunization programme managers and maternal–child health professionals
- Issuer
- Pan American Health Organization
- Edition
- 1st edition, 2026
- Audience
- Immunization programme managers, national public health officials, NITAGs, maternal–perinatal health professionals, obstetricians, midwives, paediatricians, primary care clinicians
- Evidence
- GRADE-rated WHO recommendations; systematic reviews of phase 2b/3 RCTs; postmarket effectiveness studies from 16+ countries; PAHO SAG VPD consensus recommendations
- Reviewed
- 16 Oct 2026 · GMJ
What this guideline says
GMJ summary
This comprehensive guide from the Pan American Health Organization describes RSV immunization strategies to protect infants during their first six months of life, when they are at highest risk of severe disease, hospitalization and death from respiratory syncytial virus. RSV is the leading cause of pneumonia and bronchiolitis in infants, responsible globally for 33 million episodes, 3.6 million hospitalizations and over 100 000 deaths in children under 5 years annually.
Two complementary approaches are now available: maternal RSVpreF vaccination (Abrysvo, Pfizer) administered at 32–36 weeks’ gestation, which provides passive protection through transplacental antibody transfer; and long-acting monoclonal antibodies—nirsevimab (Beyfortus, Sanofi/AstraZeneca) and clesrovimab (Enflonsia, Merck)—administered directly to newborns or infants entering their first RSV season. The maternal vaccine shows 82.4% efficacy against severe RSV lower respiratory tract disease through 90 days and 70.0% through 180 days; nirsevimab demonstrates 77.3% efficacy against hospitalization through 5 months.
PAHO recommends that countries introduce either maternal vaccination or long-acting monoclonal antibodies, or both in a hybrid strategy, based on local RSV epidemiology, economic considerations and programme capacity. The guide provides detailed implementation considerations including seasonal versus year-round administration, coadministration with other vaccines, target populations, safety monitoring requirements, and strategies for integrating RSV prevention into existing maternal and child health services.
Key points
For clinicians — doses and thresholds as stated in the guideline
- Maternal RSVpreF vaccine administered at 32–36 weeks' gestation (ideally >2 weeks before delivery) shows 82.4% (95% CI 57.5–93.9) efficacy against severe RSV lower respiratory tract disease through 90 days and 70.0% (95% CI 50.6–82.5) through 180 days after birth
- Nirsevimab: 50 mg intramuscularly for infants <5 kg bodyweight; 100 mg for infants ≥5 kg; single dose provides protection for one RSV season with 77.3% (95% CI 50.3–89.7) efficacy against hospitalization through 5 months
- Clesrovimab: 105 mg intramuscularly as single dose regardless of bodyweight for all neonates/infants entering their first RSV season; shows 84.2% (95% CI 66.6–92.6) efficacy against hospitalization through 150 days
- Do not use maternal vaccine and monoclonal antibodies concomitantly for the same mother–infant pair; monoclonal antibodies may be offered if maternal vaccination occurred <14 days before delivery
- Real-world effectiveness studies show maternal vaccine 62–79% effective against hospitalization; nirsevimab 76–83% effective in postmarket surveillance across multiple countries
- Maternal vaccine can be coadministered with Tdap, influenza and COVID-19 vaccines during pregnancy; monoclonal antibodies can be given with routine infant vaccines at different injection sites
- For children remaining vulnerable through their second RSV season (e.g., chronic lung disease, congenital heart disease): nirsevimab 200 mg as two 100 mg injections
- Countries should choose seasonal administration (just before RSV season onset) or year-round approach based on local RSV circulation patterns; year-round preferred where RSV circulates throughout the calendar year or seasonality is unclear
Efficacy of maternal RSVpreF vaccine administered between 24 and 36 weeks' gestation, MATISSE clinical trial
Table extracted from the guideline
| Outcome | Time interval | Vaccine efficacy % (95% CI) |
|---|---|---|
| RSV-positive severe medically attended LRTD | 0–90 days after birth | 82.4 (57.5, 93.9) |
| RSV-positive severe medically attended LRTD | 0–180 days after birth | 70.0 (50.6, 82.5) |
| RSV-positive medically attended LRTD | 0–90 days after birth | 57.6 (31.1, 74.6) |
| RSV-positive medically attended LRTD | 0–180 days after birth | 49.2 (31.4, 62.8) |
| RSV-associated hospitalization | 0–90 days after birth | 69.7 (37.1, 86.7) |
| RSV-associated hospitalization | 0–180 days after birth | 55.3 (23.8, 74.3) |
Source: Pan American Health Organization, Technical guide on the use of maternal vaccine and long-acting monoclonal antibodies against respiratory syncytial virus to protect infants. Reproduced in summary form.
What changed in this edition
Versus the previous edition
- Replaces the 2025 Maternal and neonatal immunization field guide for Latin America and the Caribbean: Annex on maternal respiratory syncytial virus vaccine
- Adds comprehensive guidance on long-acting monoclonal antibodies (nirsevimab and clesrovimab) in addition to maternal vaccine
- Incorporates postmarket effectiveness and safety data from 2024–2025 RSV seasons in multiple countries including Argentina, Uruguay, Chile, United States and United Kingdom
- Includes updated WHO SAGE recommendations from September 2024 and WHO position paper from May 2025
- Adds guidance on hybrid immunization strategies combining maternal vaccine and monoclonal antibodies
- Includes 2025 WHO prequalification of RSVpreF maternal vaccine and availability through PAHO Revolving Fund since 2025
From the guideline
Verbatim
“Countries should introduce either the maternal RSV vaccine (RSVpreF vaccine) or the long-acting monoclonal antibody (nirsevimab), or both to reduce the morbidity and mortality associated with RSV disease.”
Editor’s perspective
Why this matters for Georgia and the region
Prof. Giorgi Pkhakadze, MD, MPH, PhD
Editor-in-Chief, Georgian Medical Journal · Chair, Public Health Institute of Georgia · WHO consultant, health and migration
As Chair of Georgia's Public Health Institute and having advised WHO on health system strengthening, I recognise that RSV prevention represents a paradigm shift in protecting our youngest and most vulnerable infants—those under 6 months who account for half of all RSV deaths globally yet have had no preventive options until now. For Georgian clinicians, I would emphasise that the maternal vaccine at 32–36 weeks fits naturally into our existing antenatal care schedule and could be introduced alongside influenza vaccination in autumn, potentially reaching the majority of pregnant women through our 99% institutional delivery rate. However, we must be realistic about implementation challenges: current product costs are substantial and may require phased introduction targeting high-risk groups first; we need to establish robust baseline preterm birth rates before vaccine introduction to properly monitor the safety signal observed in the MATISSE trial (though postmarket data from Uruguay and Argentina are reassuring); and our RSV surveillance capacity must be strengthened to define optimal seasonal timing and measure programme impact. Given Georgia's success with hepatitis B birth-dose vaccine and our demonstrated capacity to introduce new immunizations (rotavirus in 2013, pneumococcal conjugate vaccine in 2013), we have the health system foundation to implement RSV prevention—but sustainable financing and political commitment will determine whether we can move from pilot to national scale rapidly enough to reduce the thousands of infant hospitalizations we see each winter.
ORCID 0000-0001-7609-4515 · Perspective written for the GMJ Guidelines Library, 16 Oct 2026
Applicability
Georgia and the South Caucasus
For Georgia and the South Caucasus, this guideline is directly relevant given the high burden of acute respiratory infections in infants and the region’s four-season temperate climate with clear RSV seasonality (autumn–winter peaks). Georgia’s existing antenatal care infrastructure and established immunization programme (BCG, hepatitis B birth doses already administered) provide platforms for integrating either maternal RSV vaccination or birth-dose monoclonal antibody administration. Economic considerations will be critical: maternal vaccine may be more cost-effective than monoclonal antibodies where antenatal care coverage is high (Georgia achieved 99% skilled birth attendance by 2020), while monoclonal antibodies could reach high-risk infants (premature, congenital heart disease) regardless of maternal vaccination status. National programmes will need to: establish baseline preterm birth rates before vaccine introduction for safety monitoring; define optimal vaccination timing (32–36 weeks) aligned with routine third-trimester antenatal visits; determine seasonal versus year-round administration based on local RSV surveillance data; and evaluate budget impact given current high product costs, ensuring RSV prevention does not compromise coverage of established childhood vaccines. Armenia, Azerbaijan and other South Caucasus countries face similar considerations regarding integration into maternal–child health services and establishing RSV disease surveillance to guide introduction decisions.
Questions this guideline answers
Quick answers
Can pregnant women receive RSV vaccine together with other routine pregnancy vaccines?
Yes. RSVpreF maternal vaccine can be coadministered with Tdap (tetanus-diphtheria-pertussis), influenza and COVID-19 vaccines during pregnancy. Most countries using the vaccine recommend simultaneous administration at different anatomical sites. Data show no safety concerns or reduced immunogenicity with coadministration.
Should infants receive monoclonal antibodies if their mothers were vaccinated during pregnancy?
No, not routinely. Maternal vaccine and monoclonal antibodies should not be used concomitantly for the same mother–infant pair. However, monoclonal antibodies can be offered to infants whose mothers were vaccinated <14 days before delivery (insufficient time for antibody transfer) or to high-risk infants after 6 months of age when maternal antibodies have waned.
What is the recommended timing for maternal RSV vaccination?
PAHO recommends vaccination at 32–36 weeks' gestation for optimal protection. WHO recommends ≥28 weeks with no upper limit (except active labour), ideally >2 weeks before delivery to ensure adequate antibody transfer. Countries should time vaccination so infants are protected during local RSV circulation periods.
How do we choose between seasonal and year-round RSV immunization administration?
Countries with clear, consistent seasonal RSV peaks (autumn–winter in temperate climates) can consider seasonal administration starting shortly before the RSV season for cost-effectiveness. Countries in tropical/subtropical regions where RSV circulates year-round or where seasonality is variable should adopt year-round administration. Year-round approaches are programmatically simpler and unaffected by seasonal variability.
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- Issuer
- Pan American Health Organization
- Type
- Guidelines and Technical Manuals
- Edition
- 1st edition, 2026
- Replaces
- Maternal and neonatal immunization field guide for Latin America and the Caribbean: Annex on maternal respiratory syncytial virus vaccine, 2025
- Status
- Current
- Published
- 2026-06-06
- Languages
- English (Spanish translation expected)
- Scope
- Prevention of RSV disease in infants 0–6 months through maternal vaccination or long-acting monoclonal antibodies; implementation in Americas region but globally applicable
- Audience
- Immunization programme managers, national public health officials, NITAGs, maternal–perinatal health professionals, obstetricians, midwives, paediatricians, primary care clinicians
- Pages
- 34
- Licence
- CC BY-NC-SA 3.0 IGO
- ISBN
- 978-92-75-13135-0 (PDF)
- Evidence
- GRADE-rated WHO recommendations; systematic reviews of phase 2b/3 RCTs; postmarket effectiveness studies from 16+ countries; PAHO SAG VPD consensus recommendations
- Next review
- Not stated (living document expected as new products and data emerge)
- Record history
- Created 16 Oct 2026 · updated 16 Oct 2026 · next check Apr 2027
Pan American Health Organization. Technical guide on the use of maternal vaccine and long-acting monoclonal antibodies against respiratory syncytial virus to protect infants. Washington, D.C.: PAHO; 2026. Available from: https://doi.org/10.37774/9789275131350GMJ Guidelines Library records are original summaries written by the GMJ editorial team from the issuer’s published document and reviewed by a physician. They do not replace the full guideline. The document is the copyright of its issuer and is linked, not hosted. Spotted an error or a newer edition? Tell the Guidelines Desk.
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