Merck RSV Drug for Foutils wins the FDA head sign, but the CDC committee which will advise its use is perplexed
A Merck medication developed to prevent diseases of the syncytial respiratory virus (RSV) in infants has won FDA approval, introducing competition to products already available from Pfizer and Sanofi.
Monday’s regulatory decision for antibodies, known in development under the name of Clesrovimab, covers its use among newborns and infants entering their first RSV season, which extends over the fall and winter months. For those who were born during the RSV season, Clesrovimab should be administered shortly after birth. Merck will market its new product under the Flsia brand.
RSV infection generally leads to symptoms resembling colds in healthy people. But in babies and the elderly, the disease caused by an RSV infection can cause fatal respiratory complications. For almost three decades, the only product approved by the FDA to protect babies from the disease from the lower respiratory tract caused by the RSV was Synagis, an antibody developed and marketed by Astrazeneca. The approval of this product only covered its use in premature babies. This antibody has a short half-life which requires a monthly dosage. More recent progress in RSV research has led to products, such as Merck’s Information, which require only one injection.
The Enfesie is an antibody designed to last in the body for about five months, which is long enough to protect an infant through a typical RSV season. The FDA decision for the product is based on the results of a phase 2B / 3 clinical trial controlled by placebo which scored 2,858 infants entering their first season of VRS. The results showed a reduction of 60.5% of the incidence of infections associated with the RSV compared to the placebo to five months. The antibody has also led to a reduction in hospitalizations associated with the RSV for five months. The most common side effect was the reactions of the injection site. In a phase 3 test which compared the influenza in Synagis, the safety of the medication Merck was comparable to the Astrazeneca product.
The presence of PFIZER in RSV is via Abrysvo, a vaccine composed of a modified version of the RSV protein antigen F. It was first approved for use in the elderly in 2023. Later that year, the vaccine was approved for maternal immunization, in which the immunization of a pregnant mother leads to the production of antibodies. Last year, the FDA expanded the Abrysvo label to include adults aged 18 to 59. Pfizer said $ 755 million in Abrysvo in 2024 in all its approved uses, down 15.1% compared to the previous year. The company has attributed the decline to a significant reduction in American vaccination rates for the elderly, partly compensated by a high demand for the use of the product for maternal immunization.
Beyfortus de Sanofi, approved in 2023, has become the dominant product for the protection of infants against the RSV. Similar to the new RSV product of Merck, Beyfortus is an antibody with prolonged action which, although technically, is intended to protect as a vaccine. The antibody is designed with the technology that gives it a half-life that lasts about five months. Sanofi R&D director Jon Heinrichs told Medcity News in 2023 that Beyfortus’ advantage over maternal immunization is that the administration can be timed to offer the greatest protection during the RSV season. On the other hand, the moment of a birth can only be estimated, so that antibodies produced from maternal immunization may no longer be effective when the RSV season arrives or can decline during the season.
Beyfortus is administered as a single intramuscular injection. Sanofi declared $ 1.6 billion in income for the product in 2024, more than double of its sales the previous year. Unlike Beyfortus, the dosage of which depends on the weight of a patient, the Merck’s Information is given as the same dose of 105 mg, regardless of the patient’s weight. In a prepared statement, Dean Li, president of the Merck Research Laboratories, said the company has committed to making the efonsia available before the start of the next RSV season.
The recommendations for the use of vaccines come from the Center for the Fight against Diseases and the Consultative Committee for Vaccination Practices (ACIP) of Centers for Disease and Prevention. This committee should meet from June 25 to 27. Merck said he expects the AIPI to discuss the Enfonsie at this meeting.
When the ACIP meeting occurs, it will have an entirely new list. The Ministry of Health and Human Services announced on Monday that the 17 members’ committee members had been withdrawn. HHS said 13 of these members had been appointed in 2024 under President Biden. All members will be replaced by new members currently under study. HHS secretary, Robert F. Kennedy Jr., said in the announcement that “clean scanning was necessary to restore public confidence in vaccine science”. Kennedy continued to assert, without evidence, that the Committee of Independent Advisers had worked “as a rubber stamp for industry profit programs”.
The American Medical Association challenged the dismissal of the members of the ACIP, declaring that the Committee had been faithful to provide advice and advice focused on science and data.
“Doctors, parents, community leaders and public health officials are counting on them for clinical advice, public health and knowledge information,” said Dr. Bruce Scott, president of the association, in a statement sent by email. “Today’s action to remove the 17 members in office of the ACIP SAPE who trust and upset a transparent process that has saved an countless life.
Photo: Christopher Occhicone / Bloomberg, via Getty Images
