First RSV vaccine that protects babies in the womb is approved worldwide

RSV vaccine for pregnant women

First RSV vaccine that protects babies in the womb is approved worldwide

This week, the United States became the first country to approve a respiratory syncytial virus (RSV) vaccine for pregnant women that has been proven to protect babies in the womb. The mother’s antibodies are transferred to the little ones and immunity against severe forms of the infection remains for at least the first six months, according to clinical studies.

With the endorsement of the Food and Drug Administration (FDA) agency — with a function similar to that of the National Health Surveillance Agency (Anvisa) —, the first vaccine against RSV for pregnant women is named Abrysvo and was developed by the North American pharmaceutical company Pfizer. The single-dose immunizer can be applied between the 32nd and 36th week of pregnancy.

Why a vaccine against RSV infections in babies?

Among respiratory viruses, RSV is one of the most common and causes infections in individuals of all age groups. However, “infants are among those most at risk for the severe form of the disease, which can lead to hospitalization,” explains Peter Marks, director of the FDA’s Center for Biological Evaluation and Research, in a statement.

Among the problems is the fact that RSV infection is the most frequent cause of lower respiratory tract illness in infants worldwide, according to the FDA. This indicates that the level of exposure of babies is potentially high, which implies an increased risk for pneumonia and bronchiolitis.

In clinical studies involving nearly 7,000 pregnant women, researchers found that the Pfizer vaccine reduced severe forms of RSV infection in 82% of infants aged up to 3 months and in 69% of infants aged up to 6 months.

RSV vaccine

RSV vaccine side effects

Overall, the most common adverse effects of the Abrysvo RSV vaccine for pregnant women were:

  • Pain at the injection site;
  • Headache;
  • Muscle pain;
  • Nausea and vomiting.

In addition, safety data indicated a slightly higher incidence of pre-eclampsia — increased blood pressure during pregnancy — in 1.8% of vaccinated women, compared with 1.4% of those who received a placebo. Other possible rare adverse effects are the increased risk of the baby being born with low birth weight and cases of jaundice. All these possible adverse effects will be investigated in further studies.

More ways to prevent and treat RSV infection

Here, it is important to highlight that Pfizer’s RSV vaccine can also be applied to adults over 60 years of age. In addition, the immunizer Arexvy, from the British pharmaceutical company GSK, is also indicated for the elderly in the prevention of infection by the respiratory virus.

Recently, US authorities also approved a new antibody treatment developed by Sanofi and AstraZeneca, Beyfortus, as a preventive therapy against RSV for infants and young children.

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