FDA approves Merck RSV monoclonal antibody shot for infants

News brief
Topics
Respiratory Syncytial Virus (RSV)

Merck announced yesterday that the US Food and Drug Administration (FDA) has approved its monoclonal antibody vaccine clesrovimab-cfor (Enflonsia) for preventing respiratory syncytial virus (RSV) in newborns and infants entering their first RSV season.

Enflonsia
Photo: Courtesy of Merck

There are now two monoclonal antibody shots to help protect infants against RSV. The other, called nirsevimab-alip (Beyfortus), was approved in July 2023.

In a statement, Merck said the vaccine is given as a 105 mg dose and is designed to provide direct, rapid protection through 5 months, the length of a typical RSV season. It added that Enflonsia is the only RSV preventive that is administered to infants at the same dose, regardless of weight.

Octavio Ramilo, MD, chair of the Department of Infectious Diseases at St. Jude Children’s Research Hospital and investigator for two clinical trials involving the vaccine, said RSV is the leading cause of infant hospitalization and can lead to serious respiratory conditions including bronchiolitis and pneumonia. “Enflonsia combines dosing convenience with strong clinical data showing significant reductions in RSV disease incidence and hospitalizations, making it a promising new intervention to help protect infants from RSV,” Ramilo said.

The approval was based on results from a phase 2b/3 clinical trial that evaluated a single dose given to preterm and full-term infants. The trial met primary and secondary endpoints, reducing RSV-related medically attended lower respiratory infections by 60.5% when compared to placebo over 5 months. Enflonsia also reduced RSV hospitalizations through 5 months by 84.3%, showing increased efficacy with increasing disease severity.

The company said FDA’s approval was also supported by a phase 3 trial that evaluated safety and efficacy when compared to palivizumab, an older monthly monoclonal antibody injection available for high-risk infants, in babies at increased risk for severe disease. 

ACIP to discuss recommendation later this month

Merck said the US Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices is slated to discuss a recommendation for Enflonsia at its meeting later this month and that it anticipated that ordering will begin in July in time for deliveries to begin before the start of the 2025-2026 RSV season.

Arizona confirms first measles cases as totals rise in other states

News brief
Topics
Measles

Arizona health officials reported the state’s first measles cases of the year, four Navajo County individuals who were not vaccinated and had a recent history of international travel, the Navajo County Public Health Services District said in a June 9 statement. All four people were exposed through a single source.

measles teen
Natalya Maisheva/iStock

Meanwhile, the Colorado Department of Public Health and Environment yesterday reported two new measles cases, one of them a child younger than 5 years old who had received one dose of measles, mumps, and rubella (MMR) vaccine. The child had recently traveled with family to Ontario, Canada, which has been the hot spot in Canada’s measles outbreak.

The other patient is an unvaccinated adult from Arapahoe County who was at Denver International Airport on May 13 during the exposure period of an out-of-state traveler who flew while infectious. The case appears to be the eighth linked to a cluster at Denver International Airport, which included four passengers on a Turkish Airlines flight and three others who were at the facility during the exposure period.

Texas reports 2 more cases

Meanwhile, the pace of infections in the West Texas outbreak continues to slow. The Texas Department of State Health Services today reported 2 more cases, raising the outbreak total to 744. The number of counties with ongoing transmission continues to shrink and is now at four: Dawson, Gaines, Lamar, and Lubbock. 

A few other states have reported cases linked to the activity in West Texas. New Mexico and Oklahoma didn’t report any new cases today, but yesterday the Kansas Department of Health and Environment reported one more case in an outbreak in the southwestern part of the state, raising the outbreak total to 70 cases and the overall state total to 72. 

This week's top reads

  1. Colorado confirms 3 more infections in airport-linked measles outbreak

    Other states report more cases, including Minnesota, with two, one of which involves a child whose infection suggests community spread.

    Lisa Schnirring
    DIA

  2. Kennedy removes all ACIP members, eyes replacements

    Kennedy said a 'clean sweep' of all 17 current members of the CDC's vaccine advisory board is necessary to re-establish public confidence in vaccines.

    Lisa Schnirring
    RFK Jr. giving a speech

  3. FDA approves Moderna's new COVID-19 vaccine

    The company's "next-generation" COVID-19 vaccine, mNexspike, was approved for adults 65 and older and younger people at risk of severe disease.

    Chris Dall

  4. US measles total jumps by 80, fueled by travel and more outbreaks

    In other developments, Canada reported its first measles death of the year, a premature infant born to an infected mother.

    Lisa Schnirring
    airport line

  5. 1 in 5 COVID survivors still have symptoms 3 years after severe infection, analysis estimates

    Neurologic, pulmonary, and cardiovascular manifestations were most prevalent.

    Mary Van Beusekom
    Older man in park with shortness of breath

  6. Long-COVID diagnoses fairly common in Medicare claims

    Beneficiaries with 4 or more COVID-19 vaccine doses had a 39% lower rate of long COVID.

    Stephanie Soucheray

  7. Sierra Leone battles intense mpox activity as Ethiopia reports first death

    Population density and tourism are among factors driving infections in Sierra Leone, which made up 53% of mpox illnesses in Africa last week.

    Lisa Schnirring
    mpox lesions

  8. US valley fever cases may be 18 times higher than reported

    The findings underscore the need for improved awareness, education, testing practices, and reporting to achieve better patient outcomes, the authors say.

    Mary Van Beusekom
    Coccidioides fungus

  9. Colorado announces another measles case linked to Turkish Airlines flight

    The latest case-patient is a vaccinated adult Denver resident who was a passenger on Turkish Airlines flight 201.

    Stephanie Soucheray

  10. Study finds live avian flu virus in raw milk for more than 1 day at room temperature, 1 week in fridge

    The results of the non–peer-reviewed research highlight the risk of contracting H5N1 avian flu from unpasteurized dairy products or occupational exposure in dairies.

    Mary Van Beusekom

Our underwriters