Baby dies days after receiving Moderna's mRNA RSV vaccine
A U.S. report describes a 3-month old who became lethargic and feverish after an adult-only mRESVIA injection and died four days later; Health Canada now says the shot shouldn't be given to anyone under 2.
On November 12, researcher Jessica Rose highlighted a U.S. safety report on the death of a three-month-old boy a few days after he was given mRESVIA, Moderna's newest mRNA RSV vaccine.
The Vaccine Adverse Event Reporting System entry, VAERS ID 2880791, says the infant got mRESVIA on December 1, 2025, at a private facility in Texas. It describes a baby who "was lethargic, had difficulty staying awake, [and had] low grade fever." The outcomes listed are death and sudden infant death syndrome, and the report states: "Baby passed of SIDS around 2AM on December 5, 2025." VAERS received the report on January 6, and the lot number is unknown.
VAERS reports are unverified and, on their own, do not establish that a vaccine caused a death. However, the timeline and the circumstances surrounding how this shot was administered to an infant raise warrants close scrutiny.
See, mRESVIA is not authorized for anyone under 18. The U.S. Food and Drug Administration approved it on May 31, 2024, for adults 60 and older, then expanded that on June 12, 2025, to adults 18 to 59 at increased risk. Health Canada authorizes the same groups.
As reported, British Columbia is using only Moderna's mRESVIA in its adult RSV program this fall. In April, Canada's National Advisory Committee on Immunization noted that there's less safety and effectiveness data for Moderna's shot than for the protein-based alternatives.
The shot was never meant for babies, and Moderna's own infant trial showed why.
In July 2024, Moderna paused a Phase 1 infant trial after a safety signal, and the FDA placed it on clinical hold on July 19, 2024. An FDA briefing that December said more vaccinated infants developed severe RSV lower-respiratory infections than infants given a placebo, raising concern about vaccine-associated enhanced respiratory disease.
The FDA label, revised in August of this year, now warns of more severe or hospitalized RSV cases in infants vaccinated at five to seven months of age. Health Canada went further. Its product monograph, updated August 19, says mRESVIA "is contraindicated in children less than two years of age due to an increased risk of severe and/or life-threatening RSV-enhanced respiratory disease reported in infants during a pediatric study."
This isn't the first adult RSV vaccine to end up in a baby.
CDC researchers reported in Pediatrics that VAERS received 34 reports of Pfizer's or GSK's adult RSV shots being given by mistake to children under two, between August 21, 2023, and March 18, 2024.
Parents deserve to know how an adult-only shot ended up in a baby who cannot consent, and regulators owe them an answer about what will stop it from happening again.
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