Pfizer bronchiolitis vaccine: who is Abrysvo for?

The laboratory Pfizer has developed a vaccine against the virus responsible for the bronchiolitis (respiratory syncytial virus or RSV). It’s about VRSpreF®which was the subject ofclinical tests and which received on July 20, 2023 a favorable opinion for marketing authorization by the Committee for Medicinal Products for Human Use (CHMP) of theEuropean Medicines Agency (EMA). This vaccine, in the form of powder and solvent to be transformed into a solution for injection, must be administered to mother during pregnancyin order to protect the newborn from birth until the age of 6 months, the period when it is most vulnerable in the event of bronchiolitis. In May 2023, the United States Food and Drug Administration (FDA) approved VRSpreF asABRYSVO® for the prevention of lower respiratory tract disease caused by RSV during pregnancy and in persons 60 years of age and older. As a reminder, there is no vaccine against bronchiolitis available in France for infants. There is only one vaccine (Synagis®) developed by AstraZeneca but the latter is only available for premature or at-risk infants and another vaccine (Beyfortus®) developed by Sanofi and AstraZenecaauthorized by the European Medicines Agency, but not yet by the ANSM for France.

What are the indications for Pfizer’s bronchiolitis vaccine?

The vaccine Abrysvo® is indicated for passive protection against lower respiratory tract disease caused by respiratory syncytial virus (RSV) in infants from birth to 6 months after maternal immunization during pregnancy and for active immunization 60 year olds and more for the prevention of lower respiratory tract disease caused by RSV.

Is it available in France?

For the moment, this vaccine is not marketed either in Europe or in France. Based on clinical trial results, Pfizer announced on July 20, 2023 that its vaccine had received a favorable opinion from the Committee for Medicinal Products for Human Use (CHMP). It should soon be put on the market in Europe, and therefore in France. This is the first maternal vaccine available to help prevent this common and potentially fatal respiratory disease in young infants.

What is the name of Pfizer’s bronchiolitis vaccine?

The bronchiolitis vaccine developed by Pfizer is called VRSpreF® in French And ABRYSVO® in the United States.

It is a maternal vaccine which comes in the form of a powder and a solvent to be transformed into a solution for injection. This means that it must be administered, in a single dose of 120µg, pregnant women (between the end of the 2nd trimester of pregnancy and the beginning of the 3rd) to help protect their infant against RSV after birth. If marketed, it would be the first bronchiolitis vaccine to protect infants via maternal immunization.

How effective is Pfizer’s bronchiolitis vaccine?

Pfizer’s VRSpreF® vaccine successfully passed phase 3 clinical trials. At the end of the trial in which the vaccine was administered to 7,400 pregnant women in 18 different countriesthe laboratory announced a vaccine efficacy of:

► 82% against serious diseases of the lower respiratory tract requiring medical assistance, to infants of the birth in the first three months of life

► 70% against serious diseases of the lower respiratory tract requiring medical assistance, to infants during the first six months of life.

► The trial did not conclude a “statistically significant” reduction in non-severe cases.

To date, these results have not yet been published in a medical journal or reviewed by outside scientists.

What are the side effects of Pfizer’s bronchiolitis vaccine?

The vaccine still in the experimental stage seems to have been tolerated “without any security issues” for vaccinated people and their newborns. It would not a priori have any significant side effects in addition to the undesirable effects inherent in all vaccines (slight fever, myalgia-like pain, headache or redness at the injection site).