Infant deaths in clinical trials for RSV shot not linked to injection | Fact check

The claim: RSV treatment killed 12 infants in a clinical trial

A Jan. 27 Instagram post (direct link, archive link) shows a screenshot of a headline about a new RSV treatment.

"Despite 12 Deaths During Clinical Trials, CDC Signs Off on RSV Shots for Newborns," reads the headline.

The post was liked more than 900 times in a week.

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Our rating: False

All of the deaths were investigated, and none were tied to the treatment being studied, according to researchers and the Food and Drug Administration, which oversees clinical trials.

Infant deaths had numerous, unrelated causes

Several thousand infants were part of a series of global trials investigating the efficacy and safety of nirsevimab, a monoclonal antibody for RSV developed by AstraZeneca and Sanofi. It is now sold under the brand name Beyfortus.

Over the course of the trials, 12 infants who received a monoclonal antibody died, according to a briefing packet prepared for a June 2023 FDA advisory panel meeting on the treatment.

Those records show 11 of the infants who died received Beyfortus and one received palivizumab, a monoclonal antibody that the FDA had already approved.

But none of those deaths were found to be caused by the treatment, according to the FDA. The causes of death for the infants identified in the report include a car accident, a tumor, congenital heart disease and untreated gastroenteritis, along with other co-morbidities and health issues. Some of them were noted to be common causes of infant deaths in the regions where the trials took place.

“The FDA carefully reviewed the cases of deaths reported in pivotal nirsevimab studies through 360 days post-dose to assess causality and concluded that none of the deaths in the clinical trials were considered to be related to Beyfortus,” an FDA spokesperson told USA TODAY in an email.

An email from AstraZeneca’s communications department echoed the finding, also noting that the percentage of deaths in the Beyfortus studies was lower than the global infant mortality in 2021, went the study was done. The spokesperson declined to provide a name.

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The post and user comments also muddle two key details about Beyfortus and what the Centers for Disease Control and Prevention did.

Beyfortus is not a vaccine, as some commenters believed. A vaccine stimulates a response from the immune system so it will protect recipients from a pathogen, while monoclonal antibodies, such as Beyfortus, are lab-created proteins that can provide immediate but possibly short-lived protection.

The post also says the CDC approved the use of Beyfortus, but that was a decision by the FDA, which oversees clinical trials, in July 2023. The CDC added it to a list of recommended immunizations for children – which includes both vaccines and monoclonal antibodies – in August 2023. Adoption of the treatment was initially hampered by cost and supply challenges.

The article screenshotted in the Instagram post is from Children’s Health Defense, an organization started by now-presidential candidate Robert F. Kennedy Jr. that advocates against many FDA-approved vaccines for children.

USA TODAY reached out to the social media user who shared the claim for comment but did not immediately receive a response., Lead Stories, PolitiFact and the Associated Press also debunked versions of the claim.

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This article originally appeared on USA TODAY: RSV trial deaths from unrelated illnesses, car crash | Fact check