The Centers for Disease Control and Prevention (CDC) has refined its recommendations for which older adults should receive a vaccine against respiratory syncytial virus (RSV). It now states that only adults 75 and older, or those ages 60 to 74 who are at high risk, should get the shot. This adjustment stems partly from the observation that the vaccine might slightly increase the risk of a rare side effect, Guillain-Barré syndrome (GBS), which can sometimes lead to paralysis or even death.
RSV, a seasonal respiratory virus, hospitalizes 60,000 to 160,000 older adults in the U.S. annually. An estimated 6,000 to 10,000 individuals in this age group succumb to RSV infection each year. The first-ever RSV vaccine was approved last year, with three now available for use in individuals 60 and older: GSK’s Arexvy, Pfizer’s Abrysvo, and, most recently, Moderna’s mResvia.
Initially, the CDC advised that all adults 60 and older could receive a single dose of one of these RSV vaccines after consultation with their physician. However, the CDC’s Advisory Committee on Immunization Practices has concluded that, based on current evidence, the benefits of RSV vaccination do not definitively outweigh the potential harms for adults ages 60 to 74 who lack risk factors for severe RSV. Nevertheless, individuals in this age range with risk factors might still experience benefits from vaccination.
With this in mind, the CDC suggests that healthcare providers maintain flexibility in offering RSV vaccines to patients they deem at increased risk for severe disease, even if those individuals don’t fit into a clearly defined risk category. This means that individuals ages 60 to 74 can still consider the shot if they have a heightened risk of severe RSV infections. This would encompass those with chronic heart disease or a weakened immune system, as well as those living in long-term care facilities such as nursing homes.
The report highlights that individuals who have already received an RSV vaccine should not receive another dose. These updated recommendations arise from the observation of higher-than-expected rates of GBS associated with the vaccines. GBS can cause tingling, numbness, and muscle weakness, potentially progressing to paralysis. In severe cases, GBS can impact muscles that support breathing, becoming life-threatening.
The GSK and Pfizer RSV vaccine trials in older adults hinted at this elevated risk of GBS. However, the trials were too small to definitively confirm that the vaccines themselves increased GBS rates. With wider use of these vaccines for about a year, a clearer picture has emerged: The rate of GBS among vaccine recipients is higher than the expected background rate of GBS in this age group.
For a vaccine with no associated risk of GBS, one would anticipate approximately 2 cases per 1 million doses administered. In contrast, the Pfizer vaccine was linked to about 5 cases per 1 million doses. Despite this, data suggests that the overall risk of developing GBS remains quite low. Nonetheless, this slight increase in risk was a factor experts considered when re-evaluating vaccine recommendations. Notably, there was no uptick in GBS observed in the trials of Moderna’s RSV vaccine. However, this vaccine was only recently approved, so wider surveillance hasn’t yet been conducted.
The new CDC guidelines don’t explicitly instruct individuals to discuss the risks and benefits of the shots with their doctors. The recommendations are now explicitly grounded in age and identified risk factors. The CDC asserts that the benefits are clear, particularly for individuals ages 75 and older. Previously, the recommendations were less direct, causing doctors to find them confusing and time-consuming to implement. Consequently, RSV vaccine coverage was similar for adults with and without risk factors, whereas, ideally, at-risk populations would exhibit higher rates.
As of spring 2024, an estimated 20% to 25% of U.S. adults ages 60 and older had received an RSV vaccine. This article is intended for informational purposes only and does not constitute medical advice.
