Social media post misleads about children’s deaths in RSV drug clinical trials

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Twelve children died in pediatric clinical trials after receiving shots of nirsevimab, which is sold under the brand name Beyfortus.
The monoclonal antibody treatment, a type of passive immunization that’s different from vaccines’ active immunization, was approved and recommended by U.S. health agencies in 2023 to protect young children against respiratory syncytial virus.
None of the deaths in the clinical trials were tied to the drug, the FDA said. The children died of other causes including COVID-19 and a fractured skull, or had underlying conditions such as lower respiratory tract infections.
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A new drug to protect newborns and infants against respiratory syncytial virus, or RSV, has prompted concern on social media about children’s deaths during the drug’s clinical trials.

A federal health agency says the children died from other causes, not the drug.

A Jan. 27 Instagram post has sticker text on a video that said, "When the CDC signs off on a new RSV (syringe emoji) after 12 deaths in the clinical trials." A man in the video says, "Hold up. Wait a minute. Something ain’t right."

The video also includes a screenshot of a headline about the deaths from The Defender, a website for Children’s Health Defense, an anti-vaccine organization founded by Robert F. Kennedy Jr.

The post was flagged as part of Meta’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Meta, which owns Facebook and Instagram.)

The post accurately notes the number of deaths in clinical trials for the drug nirsevimab, but it misleads because none of them were tied to the drug.

(Instagram screenshot)

Nirsevimab — sold under the brand name Beyfortus by AstraZeneca — is not a vaccine, but a monoclonal antibody product that provides up to five months of protection against RSV in newborns, infants and children up to 2 years old. The CDC calls it a passive immunization, different from vaccines’ active immunization.

The U.S. Food and Drug Administration in July 2023 approved the drug for babies entering their first RSV season and for children up to age 2 who are vulnerable to RSV. The Centers for Disease Control and Prevention recommended the drug a month later for the 2023-24 RSV season. These seasons generally start in the fall and peak in the winter, the CDC said.

RSV is a common respiratory virus that is typically mild and similar to a cold for most adults and healthy children. But it can cause severe illness in some babies and infants.

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Up to 3% of children in their first year of life are hospitalized with RSV infections, and up to 80,000 children younger than 5 are hospitalized annually, the American Academy of Pediatrics said. RSV is the leading cause of hospitalization in infants, the American Lung Association said.

In five pediatric clinical trials for nirsevimab, there were 12 deaths of children out of 3,710 who had taken the drug, versus four deaths out of 1,797 in the placebo control groups, the FDA noted in a June 2023 briefing document.

None of the 12 deaths, however, were caused by the drug, the FDA said.

Eight deaths were "clearly unrelated" to the drug, the agency wrote. That included three deaths of children with congenital heart disease, two with untreated gastroenteritis, one with COVID-19, one with a tumor and one with a fractured skull after being hit by a car, the FDA said.

Two children died of lower respiratory tract infections, one with severe malnutrition and one with multiple underlying conditions. One of those children had been taken home from a hospital against medical advice.

Two other children died of "unknown" causes and were found dead in their cribs, the FDA said. One had multiple prior hospitalizations and may have had "an underlying congenital metabolic or chromosomal anomaly." The other child was healthy and the death was "consistent with sudden infant death syndrome," the FDA report said, noting autopsy results were not available and the cause of death is unknown.

The FDA briefing also noted the mortality rate in infants who had received the drug — 3.1 per 1,000 — was much lower than the 2021 global infant mortality rate of 28 infant deaths per 1,000 live births.

The FDA concluded in its briefing that the majority of deaths were related to causes other than the drug and others were complicated by underlying conditions.

"None of the deaths were judged as related to the study drug product. At this time, it is the assessment of the Agency that none of the deaths were likely related to the study drug," the agency concluded.

An Instagram post claimed that 12 children died from taking an RSV drug in clinical trials, but the FDA said those deaths were not related to the drug being studied. We rate the claim False.