https://www.cidrap.umn.edu/respirat...v-vaccination-highly-effective-against-infant
Maternal RSV vaccination highly effective against infant hospitalization
Laine Bergeson
Today at 9:36 a.m.
Respiratory Syncytial Virus (RSV)
Australia introduced a maternal RSV vaccination program in February 2025 to encourage pregnant women to receive the bivalent (two-strain) RSVpreF vaccine (Abrysvo) from 28 weeks’ gestation.
The study findings, published this week in JAMA Pediatrics, draw on data from more than 1,000 infants at nine hospitals born during the first year of the vaccination program.
RSV is the leading cause of lower respiratory tract disease (LRTD) in infants globally, with most hospitalizations occurring during the first three months of life, when the most severe outcomes often occur. Australia offers the vaccine year-round, because RSV circulation varies across the country, with seasonal peaks in the southern states and year-round activity in the north.
Protection strongest in first 2 months of life
For the study, researchers from Wesfarmers Centre for Vaccines and Infectious Diseases at the Kids Research Institute Australia analyzed 1,012 infants 6 months or younger who were hospitalized with acute respiratory infection (ARI) from March 2025 to February 2026. Maternal vaccination was defined as receipt of RSVpreF at least 14 days before delivery.
The researchers found that maternal vaccination was 77.8% effective against hospitalization for any RSV-associated LRTD through 6 months of age. Protection was highest early in life: Among infants 2 months and younger, vaccine effectiveness (VE) was 86.3%. From birth through 3 months, VE was 80.2%.
Comparable VE was observed for hospitalization for severe RSV-related LRTD (80.4%) and RSV-associated ARI (80.8%). Among all infants hospitalized with respiratory illness, 32% of those born to unvaccinated mothers had developed LRTD, compared with 17% of those whose mothers had been vaccinated.
Protection consistent, regardless of timing
Effectiveness remained similar, regardless of when pregnant women were vaccinated during the recommended window, the length of interval between vaccination and delivery, or whether RSVpreF was given near the time of another vaccine. The vaccine demonstrated protection against both the RSV-A strain and RSV-B.
The findings are consistent with studies in countries, such as the United States, that use RSVpreF as their primary immunization strategy or as part of hybrid prevention strategies, write the researchers.
While they call for ongoing evaluation to monitor VE over time, they conclude that their findings “support the effectiveness of maternal immunization as a key component of Australia’s RSV Maternal and Infant Protection Program, with the greatest benefit observed during the earliest, highest-risk months of life.”
Maternal RSV vaccination highly effective against infant hospitalization
Laine Bergeson
Today at 9:36 a.m.
Respiratory Syncytial Virus (RSV)
Vaccination against respiratory syncytial virus (RSV) during pregnancy is highly effective in preventing RSV-related hospitalization in infants aged 6 months or younger, according to a new study from Australia, with protection strongest during the first months of life.Australia introduced a maternal RSV vaccination program in February 2025 to encourage pregnant women to receive the bivalent (two-strain) RSVpreF vaccine (Abrysvo) from 28 weeks’ gestation.
The study findings, published this week in JAMA Pediatrics, draw on data from more than 1,000 infants at nine hospitals born during the first year of the vaccination program.
RSV is the leading cause of lower respiratory tract disease (LRTD) in infants globally, with most hospitalizations occurring during the first three months of life, when the most severe outcomes often occur. Australia offers the vaccine year-round, because RSV circulation varies across the country, with seasonal peaks in the southern states and year-round activity in the north.
Protection strongest in first 2 months of life
For the study, researchers from Wesfarmers Centre for Vaccines and Infectious Diseases at the Kids Research Institute Australia analyzed 1,012 infants 6 months or younger who were hospitalized with acute respiratory infection (ARI) from March 2025 to February 2026. Maternal vaccination was defined as receipt of RSVpreF at least 14 days before delivery.
Protection was highest early in life: Among infants 2 months and younger, vaccine effectiveness was 86.3%.
The researchers found that maternal vaccination was 77.8% effective against hospitalization for any RSV-associated LRTD through 6 months of age. Protection was highest early in life: Among infants 2 months and younger, vaccine effectiveness (VE) was 86.3%. From birth through 3 months, VE was 80.2%.
Comparable VE was observed for hospitalization for severe RSV-related LRTD (80.4%) and RSV-associated ARI (80.8%). Among all infants hospitalized with respiratory illness, 32% of those born to unvaccinated mothers had developed LRTD, compared with 17% of those whose mothers had been vaccinated.
Protection consistent, regardless of timing
Effectiveness remained similar, regardless of when pregnant women were vaccinated during the recommended window, the length of interval between vaccination and delivery, or whether RSVpreF was given near the time of another vaccine. The vaccine demonstrated protection against both the RSV-A strain and RSV-B.
The findings are consistent with studies in countries, such as the United States, that use RSVpreF as their primary immunization strategy or as part of hybrid prevention strategies, write the researchers.
While they call for ongoing evaluation to monitor VE over time, they conclude that their findings “support the effectiveness of maternal immunization as a key component of Australia’s RSV Maternal and Infant Protection Program, with the greatest benefit observed during the earliest, highest-risk months of life.”