Currently at the experimental stage, VRSpreF, developed by Pfizer, would be the first vaccine against bronchiolitis administered to pregnant women during pregnancy to protect their babies from birth against severe forms of this disease.
The laboratory Pfizer has developed a vaccine against the virus responsible for the bronchiolitis (respiratory syncytial virus or RSV). It’s about VRSpreF®currently in clinical trial and so not yet marketedspecifies the laboratory in a statement November 1, 2022. This vaccine should 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. 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 is the name of Pfizer’s bronchiolitis vaccine?
The bronchiolitis vaccine developed by Pfizer is called VRSpreF® in French and RSVpreF® in English.
The VRSpreF® vaccine is a maternal vaccine. 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 is currently in a phase 3 clinical trial. 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.
When will it be available in France?
For the moment, this vaccine is not marketed either in Europe or in France. Based on the clinical trial results, Pfizer expects to submit its first regulatory application by the end of 2022 in the United States, then in other countries in the months to come. If approved, Pfizer’s RSV vaccine candidate could be the first maternal vaccine available to help prevent this common and life-threatening respiratory disease in young infants.
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, pain or redness at the injection site).
Source : Pfizer Announces Positive Top-Line Data of Phase 3 Global Maternal Immunization Trial for its Bivalent Respiratory Syncytial Virus (RSV) Vaccine Candidate, Pfizer press release, November 1, 2022