The US became the first country to approve a vaccine for pregnant women against respiratory syncytial virus (RSV), in order to prevent bronchiolitis in their babies . It did so after the Food and Drug Administration of that country (FDA) published a statement on August 21 that gave the green light to the use of Abrysvo, from Pfizer, for use between weeks 32 and 36 of gestation.
It is a single intramuscular injection and its application in pregnant people will allow babies to be protected during the first six months of life.
This virus "is a common cause of illness in children, and infants are among those most at risk for severe illness, which can lead to hospitalization," said Peter Marks , director of the Center for Evaluation and Research. FDA Biological.
The clinical trial, in which about 7,000 pregnant women participated, showed that the vaccine, called Abrysvo, reduced the severe variant of the disease by 82% in babies from 0 to 3 months and by 69% from 0 to 6 months.
RSV usually causes mild, cold-like symptoms in infants and young children, but also pneumonia and bronchiolitis. An estimated 58,000 to 80,000 children under five are hospitalized due to RSV infection, according to the Centers for Disease Control and Prevention (CDC), making it the leading cause of hospitalization among infants. .
Among the most common side effects in pregnant women vaccinated with Abrysvo are discomfort at the injection site, headache or muscle pain, and nausea.
A dangerous blood pressure disorder, known as preeclampsia, occurred in 1.8% of cases, compared to 1.4% of those who received a placebo.
The FDA also noted an imbalance in premature births between the vaccine and placebo groups (5.7% vs. 4.7%). That is why the prescribing information for Abrysvo includes a warning to report this difference, beyond the fact that “the available data are insufficient to establish or exclude a causal relationship between premature birth and Abrysvo,” the FDA detailed.
Specifically, the warning informs healthcare providers that to avoid the potential risk of preterm birth with use of Abrysvo before 32 weeks gestation, administer Abrysvo as directed to pregnant women at 32 to 36 weeks gestational age. Pregnant people who were at increased risk of preterm birth were generally excluded from clinical studies of Abrysvo.
As a result, the agency asked Pfizer to continue studying the risk of premature birth and preeclampsia.
