CDC Narrows RSV Vaccine Guidelines Due to Safety Concerns

The U.S. Centers for Disease Control and Prevention (CDC) has recently narrowed its original recommendations for the respiratory syncytial virus (RSV) vaccine, citing concerns over the risk of a side effect that can lead to paralysis or death. The recommendations originally stated adults over the age of 60 should receive the vaccine, but updates in early August recommend the vaccine for adults 75 and older, or those ages 60 to 74 who are at high risk.¹

Guillain-Barre Syndrome “More Common than Expected” During RSV Vaccine Trials

The first ever RSV vaccine Arexvy was approved last year, despite the nervous system disorder Guillain-Barre syndrome (GBS) being “more common than expected” in trial data. GBS is described as a “rare, but potentially fatal, immune-mediated disease of the peripheral nerves and nerve roots that is usually triggered by infections.”² An inflammatory  autoimmune condition, GBS damages nerve cells, leading to muscle weakness and paralysis. Most people fully recover but, in some cases, the nerve damage is permanent and can include partial or full body paralysis.³

There are now three RSV vaccines on the market for older adults including GlaxoSmithKline’s Arexvy, Pfizer’s Abrysvo and, most recently, Moderna’s mResvia.

GBS is a known side effect of influenza and other vaccines.⁴ The RSV vaccine trials in older adults hinted at the elevated GBS risk, and now that the shots have been in wider use for a year, a clearer picture of the risk has emerged.

On Aug. 6, 2024, the CDC’s Advisory Committee on Immunization Practices (ACIP) determined that because of the potential increased risk of GBS during post licensure safety surveillance, they can no longer say “based on currently available evidence” that benefits of RSV vaccination clearly outweigh potential harms for those under age 75 who are not high risk. High risk adults are considered those with chronic heart disease, a weakened immune system, or those in long-term case facilities.^{1 5}

As of spring 2024, an estimated 20 percent to 25 percent of adults ages 60 and older had received the RSV vaccine in the United States.⁵

Uncertainty About Benefits and Risks of RSV Vaccine Leads CDC to Encourage “Shared Decision Making” With Doctors

ACIP has demonstrated uncertainty about the wording of the RSV vaccine recommendation. The original recommendation given last summer for use in adults ages 60 and older advised using “shared clinical decision making” when making the decision to get vaccinated or not. This is terminology the CDC commonly uses when uncertainty exists about benefits and risks.⁶

The CDC has acknowledged that shared clinical decision making isn’t simple in clinical practice and may contribute to unclear messaging regarding the need to vaccinate.

Following the ACIP vote, ACIP member Jamie Loehr, MD emphasized that the small but real risk of GBS weighed heavily on the risk0-benefit assessments made by ACIP members because GBS is a severe neurological disease that can leave patients hospitalized for months.⁶

A May 2024 analysis by CDC researchers using data from the Vaccine Adverse Event Reporting System (VAERS) and V-safe, found that in adults aged 60 and older there were 4.4 reports of Guillain-Barré syndrome for every million doses of Pfizer RSV vaccine administered. There were 1.9 reports per million doses of GSK RSV vaccine. These were higher than estimated expected background rates in a vaccinated population.⁷

GBS has also been associated with the COVID vaccine. There is a reported association between GBS and the COVID vaccine—ranging from 0.81 percent to 1.91 cases per 100,000 persons.^{5 8} 

The U.S. Food and Drug Administration (FDA) fast-tracked the approval of all three RSV vaccines available to the older population.⁵

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