Work: Juanito Laguna | Antonio Berni
Consolidated results of the BERNI Study (2024–2025)
Argentina, January 2026 – Two years after the inclusion of maternal vaccination against respiratory syncytial virus (RSV) in the National Vaccination Schedule, Argentina has local, real-time evidence confirming its positive impact on the health of newborns.
The consolidated results of the 2024 and 2025 seasons of the BERNI Study show that the vaccine administered during pregnancy offers high and sustained protection against hospitalizations and severe forms of respiratory disease caused by RSV in infants under six months of age, the group at highest risk.
Why is it important?
SRV is one of the leading causes of hospitalization and death from respiratory infections in young infants. The strategy of vaccinating pregnant women allows antibodies to be passed on to the baby before birth, protecting them in the first months of life, when the risk is highest and they are not yet able to receive their own vaccines.
Key findings
The analysis included 1,143 infants hospitalized in 12 hospitals in different regions of the country, belonging to the public, private, and social security systems.
The results show that maternal vaccination:
- It showed 62.1% effectiveness (95% CI: 49.7–71.4) in preventing hospitalizations due to acute respiratory infection (ARI) caused by RSV in infants up to 180 days (6 months) old.
- It showed an effectiveness of 78.5% (95% CI: 65.2–86.8) in preventing severe forms of SARS-related ARI in that same group.
Effectiveness was highest in the first 90 days (3 months) of life.
- In infants aged 0 to 90 days, it was 75.5% effective in preventing hospitalizations due to RSV-related ARI (95% CI: 64.6–83.1) and 82.1% effective in preventing severe RSV-related ARI (95% CI: 67.0–90.3).
Protection against severe forms of the disease remained high throughout the first six months of life:
- The effectiveness in preventing severe disease was 82.1% (95% CI: 60.7–90.3) in infants aged 0 to 90 days, and 74.3% (95% CI: 38.1–89.3) in infants aged 90 to 180 days.
Consistency of effectiveness
In addition, the vaccine's effectiveness:
- It remained consistent throughout the recommended vaccination window (32 to 36 weeks of gestation) for vaccination during pregnancy.
- It was maintained when administered together with other pregnancy vaccines (same day or ±2 weeks), with an effectiveness of 61.6% in preventing hospitalization due to IRAB caused by RSV and 77.0% in preventing severe disease in infants aged 0 to 6 months.
These findings support the integration of RSV vaccination into routine prenatal care schedules.
A health decision with an impact on equity
Argentina was the first country to incorporate maternal vaccination against RSV into the National Vaccination Schedule, guaranteeing free and equitable access to all pregnant women.
Had this decision not been made, the vaccine would only have been available to those who could afford it, widening health inequalities. Inclusion in the schedule made it possible to protect newborns who need it most, regardless of their place of birth or health coverage.
Local evidence for better public policies
The BERNI Study is an example of collaboration between the public sector, academia, and industry, with the participation of the private sector (iTRIALS) and the National University of San Martín, through its hub for innovation in health and equity policies.
Generating local, real-time scientific evidence is key to:
- Assess the impact of public policies.
- Strengthen the confidence of the population and the healthcare team.
- Redouble efforts to improve vaccination coverage by 2026.
- Serve as a reference for other countries in the region and around the world to move forward with the incorporation of this vaccine and protect more newborns.
These results once again highlight the value of primary prevention through vaccines, one of the strategies that has saved the most lives in human history, along with access to safe drinking water.
Consistent results over two consecutive seasons—in different subgroups and in combination with other vaccines—reinforce the strength of the evidence. Maternal vaccination against RSV proves to be a highly effective strategy for preventing hospitalizations and severe disease in the first months of life.
