Bronchiolitis Is RSV's Serious Complication in Infants
Parents of babies under one should know how a cold can progress into a deeper chest infection.
Updated on Nov. 4, 2026 in Asthma
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Sanofi released a public service video raising awareness of bronchiolitis, a chest infection that can develop from RSV in young children. The video uses recorded breathing sounds that parents are asked to interpret, and the recording is not from a real child.
Why it matters
Bronchiolitis is the leading cause of hospitalization in infants under one, so recognizing how a typical cold can progress over several days matters for parents and caregivers. The campaign arrives as Sanofi faces declining sales of its RSV antibody Beyfortus, which it markets alongside AstraZeneca.
The figures come from Sanofi's third-quarter financial reporting, which shows Beyfortus revenue down 15.4% to €631 million overall and down 39.3% in the U.S. to €240 million year-over-year. The source does not explain the causes of the decline or report whether the awareness video has changed how parents recognize bronchiolitis.
The players
Sanofi
A French pharmaceutical company with major treatment areas in vaccines and immunology, and the marketer of the RSV antibody Beyfortus.
AstraZeneca
A British-Swedish pharmaceutical company with major therapies in oncology, cardiovascular, and respiratory disease, and Sanofi's partner in marketing Beyfortus.
U.K. Prescription Medicines Code of Practice Authority (PMCPA)
The U.K. pharmaceutical industry marketing watchdog that oversees promotional claims by drug companies.
U.S. Food and Drug Administration (FDA)
The U.S. federal agency responsible for regulating drugs, vaccines, and their promotional materials.
The details
The PSA has several parents brought into a room one at a time and played the recorded breathing sound of a baby with bronchiolitis through a speaker, then asked, 'what does this sound mean to you?' Bronchiolitis is a chest infection that can arise in some children when an RSV infection progresses, moving from a typical cold into a deeper infection over several days. Sanofi is positioning the campaign to raise awareness of this complication among caregivers of young children. The source notes Sanofi hopes the push will help sales for the coming RSV season.
Timeline
July 2026: the FDA issued an untitled letter to Sanofi about its promotion of Beyfortus.
Summer 2026: the U.K. marketing watchdog PMCPA reprimanded Sanofi over a highly misleading interpretation of data about Pfizer's RSV vaccine.
September 2026: a Keke Palmer spot for Beyfortus was released.
Late October 2026: Sanofi released third-quarter financials showing the Beyfortus decline.
November 4, 2026: Sanofi published the bronchiolitis PSA video.
Health Landscape
Beyfortus is an RSV antibody used to protect infants, and its sales decline reflects a competitive and regulatory environment shaped by scrutiny of how RSV products are promoted. The campaign is part of a broader effort by drug makers to make a case for prevention in a market where promotional claims are closely watched by regulators.
If you care for a young child, it is worth knowing that a cold with rapid breathing, labored breathing, or a worsening cough over several days can signal bronchiolitis. Raise any concerns about a child's breathing with a pediatrician promptly, since bronchiolitis is a leading cause of hospitalization in infants under one.
The takeaway
Bronchiolitis can develop from RSV and is a leading reason infants under one are hospitalized, so caregivers should know its warning signs. Talk with your child's doctor about recognizing breathing changes early and about how RSV prevention options fit into your child's care.
Further reading
For background on the respiratory conditions behind this campaign, explore our Asthma coverage.
Source note: This article includes information reported by FiercePharma.
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