Pfizer’s Abrysvo During Pregnancy Shows Strong Real-World Protection for Infants, New U.S. Data Confirms
Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S. The regional, retrospective study from UPMC confirms effectiveness seen in larger national UK studies...
Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S.
The regional, retrospective study from UPMC confirms effectiveness seen in larger national UK studies, which reported up to 82% protection.
Ongoing prospective research like the CASSATT trial will track the durability and effectiveness of Abrysvo through the 2026–27 RSV season, providing longer term real world data.
What real-world evidence from a University of Pittsburgh and UPMC study published June 5 in JAMA Network Open showed about the effectivenessNew real-world data from a UPMC study shows that maternal vaccination with Abrysvo significantly reduces RSV hospitalizations in young infants.
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Create a landscape editorial hero image for this Studio Global article: What real-world evidence from a University of Pittsburgh and UPMC study published June 5 in JAMA Network Open showed about the effectiveness. Article summary: Here is the full picture from the study and its context.. Topic tags: general, government, academic, general web, education. Reference image context from search candidates: Reference image 1: visual subject "A service of the American Association for the Advancement of Science. A study led by researchers at the University of Pittsburgh and UPMC published today in JAMA Network Open, a pe" source context "Maternal RSV vaccine cuts infant hospitalizations by 70% | EurekAlert!" Reference image 2: visual subject "# Real-world evidence on RSV vaccine uptake, effectiveness, and safety in older adults: a systematic review and meta-analysis. Respiratory syncytial virus (
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The first real-world evidence from U.S. clinical practice confirms that vaccinating pregnant individuals with Pfizer’s RSVpreF vaccine (Abrysvo) sharply reduces the risk that their infants will be hospitalized with respiratory syncytial virus (RSV). A study led by researchers at the University of Pittsburgh and UPMC, published on June 5, 2026, in JAMA Network Open, found the maternal vaccine reduced infant hospitalizations by nearly 70% .
This is the earliest American clinical data to validate the results of the pivotal phase 3 MATISSE trial and aligns closely with broader, population-level findings from public health programs in the United Kingdom.
Key U.S. Effectiveness Findings
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Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S.
What are the key points to validate first?
Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S. The regional, retrospective study from UPMC confirms effectiveness seen in larger national UK studies, which reported up to 82% protection.
What should I do next in practice?
Ongoing prospective research like the CASSATT trial will track the durability and effectiveness of Abrysvo through the 2026–27 RSV season, providing longer term real world data.
Pfizer’s Abrysvo During Pregnancy Shows Strong Real-World Protection for Infants, New U.S. Data Confirms
Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S. The regional, retrospective study from UPMC confirms effectiveness seen in larger national UK studies...
Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S.
The regional, retrospective study from UPMC confirms effectiveness seen in larger national UK studies, which reported up to 82% protection.
Ongoing prospective research like the CASSATT trial will track the durability and effectiveness of Abrysvo through the 2026–27 RSV season, providing longer term real world data.
What real-world evidence from a University of Pittsburgh and UPMC study published June 5 in JAMA Network Open showed about the effectivenessNew real-world data from a UPMC study shows that maternal vaccination with Abrysvo significantly reduces RSV hospitalizations in young infants.
AI Prompt
Create a landscape editorial hero image for this Studio Global article: What real-world evidence from a University of Pittsburgh and UPMC study published June 5 in JAMA Network Open showed about the effectiveness. Article summary: Here is the full picture from the study and its context.. Topic tags: general, government, academic, general web, education. Reference image context from search candidates: Reference image 1: visual subject "A service of the American Association for the Advancement of Science. A study led by researchers at the University of Pittsburgh and UPMC published today in JAMA Network Open, a pe" source context "Maternal RSV vaccine cuts infant hospitalizations by 70% | EurekAlert!" Reference image 2: visual subject "# Real-world evidence on RSV vaccine uptake, effectiveness, and safety in older adults: a systematic review and meta-analysis. Respiratory syncytial virus (
openai.com
The first real-world evidence from U.S. clinical practice confirms that vaccinating pregnant individuals with Pfizer’s RSVpreF vaccine (Abrysvo) sharply reduces the risk that their infants will be hospitalized with respiratory syncytial virus (RSV). A study led by researchers at the University of Pittsburgh and UPMC, published on June 5, 2026, in JAMA Network Open, found the maternal vaccine reduced infant hospitalizations by nearly 70% .
This is the earliest American clinical data to validate the results of the pivotal phase 3 MATISSE trial and aligns closely with broader, population-level findings from public health programs in the United Kingdom.
Key U.S. Effectiveness Findings
Studio Global AI
Continue your research
This page includes a source-backed answer you can continue inside Studio Global.
What is the short answer to "Pfizer’s Abrysvo During Pregnancy Shows Strong Real-World Protection for Infants, New U.S. Data Confirms"?
Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S.
What are the key points to validate first?
Maternal vaccination with Pfizer's RSVpreF (Abrysvo) reduced the risk of RSV hospitalization by 67.6% for infants under 3 months and by 73.8% for newborns in their first month, according to the first real world U.S. The regional, retrospective study from UPMC confirms effectiveness seen in larger national UK studies, which reported up to 82% protection.
What should I do next in practice?
Ongoing prospective research like the CASSATT trial will track the durability and effectiveness of Abrysvo through the 2026–27 RSV season, providing longer term real world data.
The Pittsburgh study used a retrospective, test-negative design analyzing real-world data from infants born within the UPMC health system in Western Pennsylvania. It measured vaccine effectiveness (VE) for two primary outcomes across an infant’s first 90 days of life :
The protection was even more pronounced in the first month after birth, when transferred maternal antibodies are at their peak. For infants 0 to 30 days old, effectiveness against RSV-associated ARI hospitalization was measured at 73.8% (95% CI, 10.9%–93.7%) .
A Crucial First U.S. Data Point, Despite Limitations
While the study’s findings are strong, it is important to interpret them within the context of its design. Unlike nationwide studies from the UK, this was a single-region, hospital-based retrospective analysis.
The smaller sample size resulted in wide confidence intervals for the effectiveness estimates. For the primary outcome of 67.6% effectiveness against ARI hospitalization, the true population effect could plausibly be as low as 33.2% or as high as 85.4% . The study confirmed the vaccine’s benefit but with less statistical precision than larger national analyses.
The analysis covered RSV seasons from the vaccine’s rollout through the 2024–25 and 2025–26 seasons , providing a multi-season look at protection.
How the U.S. Data Compares to UK Real-World Studies
These results are consistent with and reinforce evidence from larger national programs in the United Kingdom, where maternal RSV vaccination was also widely implemented.
A national study in Scotland, published in November 2025 in The Lancet Infectious Diseases, reported 82.2% effectiveness (95% CI, 75.1–87.3%) against RSV-associated LRTD hospitalization in infants. The study estimated that 219 infant RSV hospital admissions were averted during the 2024–25 season alone .
An evaluation of England’s program by the UK Health Security Agency (UKHSA) found that vaccination given at least four weeks before delivery provided nearly 85% protection against RSV infection in newborns, with strong effectiveness also demonstrated for premature infants .
A combined analysis from the BronchStop study in England and Scotland found a 72% reduction in infant hospitalizations when mothers were vaccinated more than 14 days before delivery .
The somewhat higher effectiveness figures from the UK (broadly in the 72%–82% range) are not in conflict with the Pittsburgh findings. The UK studies were prospective, population-based analyses with vastly larger sample sizes, leading to tighter confidence intervals. Methodological differences, including how outcomes were defined and verified, and the fact that the Pittsburgh study was a regional retrospective analysis, account for the variation. The critical conclusion is that all real-world studies confirm a substantial, clinically meaningful protective effect .
What’s Next: Tracking Durability into Future Seasons
Several ongoing research projects are now monitoring the long-term performance of maternal RSV vaccination.
The CASSATT trial (ClinicalTrials.gov ID NCT06813872) is a collaboration between Pfizer and the University of Pittsburgh that is actively enrolling and will prospectively track the real-world effectiveness of Abrysvo in infants in Western Pennsylvania. The study is designed to continue surveillance through the 2026–27 RSV season to monitor the durability of protection, any waning of immunity, and the vaccine’s effectiveness against emerging RSV strains .
Similar long-term tracking is underway in the UK. The BORLAND project (Benefits Of RSV Maternal vaccination Using A Scottish National Dataset) will use national health data to monitor outcomes across multiple future RSV seasons .
These ongoing studies will provide the longitudinal data needed to refine vaccination guidelines, understand the optimal timing of doses during pregnancy, and maintain vaccine confidence as the virus evolves.
research.ed.ac.ukBivalent prefusion F vaccination in pregnancy and ...
The Pittsburgh study used a retrospective, test-negative design analyzing real-world data from infants born within the UPMC health system in Western Pennsylvania. It measured vaccine effectiveness (VE) for two primary outcomes across an infant’s first 90 days of life :
The protection was even more pronounced in the first month after birth, when transferred maternal antibodies are at their peak. For infants 0 to 30 days old, effectiveness against RSV-associated ARI hospitalization was measured at 73.8% (95% CI, 10.9%–93.7%) .
A Crucial First U.S. Data Point, Despite Limitations
While the study’s findings are strong, it is important to interpret them within the context of its design. Unlike nationwide studies from the UK, this was a single-region, hospital-based retrospective analysis.
The smaller sample size resulted in wide confidence intervals for the effectiveness estimates. For the primary outcome of 67.6% effectiveness against ARI hospitalization, the true population effect could plausibly be as low as 33.2% or as high as 85.4% . The study confirmed the vaccine’s benefit but with less statistical precision than larger national analyses.
The analysis covered RSV seasons from the vaccine’s rollout through the 2024–25 and 2025–26 seasons , providing a multi-season look at protection.
How the U.S. Data Compares to UK Real-World Studies
These results are consistent with and reinforce evidence from larger national programs in the United Kingdom, where maternal RSV vaccination was also widely implemented.
A national study in Scotland, published in November 2025 in The Lancet Infectious Diseases, reported 82.2% effectiveness (95% CI, 75.1–87.3%) against RSV-associated LRTD hospitalization in infants. The study estimated that 219 infant RSV hospital admissions were averted during the 2024–25 season alone .
An evaluation of England’s program by the UK Health Security Agency (UKHSA) found that vaccination given at least four weeks before delivery provided nearly 85% protection against RSV infection in newborns, with strong effectiveness also demonstrated for premature infants .
A combined analysis from the BronchStop study in England and Scotland found a 72% reduction in infant hospitalizations when mothers were vaccinated more than 14 days before delivery .
The somewhat higher effectiveness figures from the UK (broadly in the 72%–82% range) are not in conflict with the Pittsburgh findings. The UK studies were prospective, population-based analyses with vastly larger sample sizes, leading to tighter confidence intervals. Methodological differences, including how outcomes were defined and verified, and the fact that the Pittsburgh study was a regional retrospective analysis, account for the variation. The critical conclusion is that all real-world studies confirm a substantial, clinically meaningful protective effect .
What’s Next: Tracking Durability into Future Seasons
Several ongoing research projects are now monitoring the long-term performance of maternal RSV vaccination.
The CASSATT trial (ClinicalTrials.gov ID NCT06813872) is a collaboration between Pfizer and the University of Pittsburgh that is actively enrolling and will prospectively track the real-world effectiveness of Abrysvo in infants in Western Pennsylvania. The study is designed to continue surveillance through the 2026–27 RSV season to monitor the durability of protection, any waning of immunity, and the vaccine’s effectiveness against emerging RSV strains .
Similar long-term tracking is underway in the UK. The BORLAND project (Benefits Of RSV Maternal vaccination Using A Scottish National Dataset) will use national health data to monitor outcomes across multiple future RSV seasons .
These ongoing studies will provide the longitudinal data needed to refine vaccination guidelines, understand the optimal timing of doses during pregnancy, and maintain vaccine confidence as the virus evolves.
research.ed.ac.ukBivalent prefusion F vaccination in pregnancy and ...
pubmed.ncbi.nlm.nih.govMaternal Respiratory Syncytial Virus Prefusion F ...
news-medical.netMaternal vaccination provides protection against RSV-associated hospitalization in early infancy
gov.ukHPR volume 20 issue 4: news (30 April 2026)