United States: This autumn signs the second iteration of Respiratory Syncytial Virus (RSV) vaccinations tailored for older populations. Whether you’ve already received one, qualify for it, or have loved ones in that category, the decision of whether to proceed often looms large. In recent weeks, I’ve addressed numerous inquiries regarding these vaccines, and this year, we’re armed with a more robust foundation of evidence.
Forgive me for diving into some statistics-heavy discourse, but this subject merits a thorough dissection. There’s also a fair amount of concern surrounding Guillain-Barré syndrome (GBS), and I’ll explain why that is relevant, according to the reports by mccormickmd.substack.com.
According to the Centers for Disease Control and Prevention (CDC), individuals aged 75 and above who haven’t already received the RSV vaccine should seriously consider doing so. Furthermore, those aged 60-74 who suffer from chronic conditions such as cardiovascular or pulmonary diseases, complex diabetes, or compromised immune function, as well as those in long-term care facilities, also meet the criteria for vaccination. The complete list of at-risk conditions that support vaccination in this group is available through the CDC.
Interestingly, no formal recommendation has been established for individuals aged 50 to 59, as the Advisory Committee on Immunization Practices (ACIP) stated that there remains insufficient data to justify a guideline for this demographic.

There are currently three vaccine options: Arexvy and Abrysvo, both in their sophomore years and a new contender from Moderna called mResvia. Approved in May 2024, mResvia, an mRNA-based vaccine, arrived too late to penetrate the fall distribution cycle for many pharmacies. Consequently, real-world data and experiential insights are more limited for this new vaccine.
Given the choice, I would lean slightly in favor of Arexvy by GSK over Pfizer’s Abrysvo. Although there hasn’t been a direct comparison between the two, post-marketing surveillance has raised a potential, albeit minor, correlation between Abrysvo and a heightened risk of GBS, which doesn’t appear as prominently with Arexvy, as reported by mccormickmd.substack.com.
As for mResvia, no reports of GBS emerged during its clinical trials.
On a personal note, my older patients who opted for the vaccine—whether Arexvy or Abrysvo—fared well last year.
The focus of this post excludes RSV vaccines for pregnant women and monoclonal antibody treatments for infants, but I have included a quick reference chart below for those interested.
Among seasonal respiratory pathogens, COVID-19 still ranks as my chief concern, followed by influenza and, finally, RSV.
Currently, RSV rates in the US remain relatively low, though they are starting to increase in the Southeast. If you plan to receive the vaccine, doing so by the end of this month is advisable.
Last year, around 24 percent of adults aged 60 and older in the US received the RSV vaccine, including over 30 percent of adults aged 70 and older. So far this year, demand is lower, likely due to the narrower age recommendations, the absence of a need for a second dose, and many early adopters already being vaccinated.
Vaccinations against severe RSV infections—whether for older adults, infants, or administered to pregnant women—are proving essential. Reflecting on my RSV vaccine article from last year, the concept of “shared decision-making” was introduced, encouraging physicians to engage in thorough discussions with patients before administering this relatively new vaccine. This proved challenging for many, given the nuanced and evolving nature of the information.
RSV in adults often arrives as a cough, sore throat, nasal congestion, runny nose, headache, low-grade fever, and fatigue. Though typically benign, RSV can escalate to pneumonia, bronchitis, and other lower respiratory tract infections, particularly in the elderly, immunocompromised individuals, and residents of long-term care facilities.
Last year, I had one unvaccinated 68-year-old patient hospitalized with RSV-induced pneumonia. Rapid testing for RSV is primarily performed in emergency departments, leaving most cases undiagnosed. In my office, we can only perform rapid testing for influenza, Covid, and strep. Recently, I saw a patient for a comprehensive review of his diabetes, hypertension, arthritis, and mental health.
At the end of our 30-minute consultation, he mentioned having a “head cold” with a sore throat, cough, and headache. Testing revealed influenza B. Thankfully, I was masked, and he is expected to recover, but he had unknowingly spread the virus for a week without a mask at work. I’ll be getting my flu shot soon, although this year’s vaccine is predicted to be only moderately effective—better than nothing, though, as per mccormickmd.substack.com.

Returning to RSV, in the US, the virus leads to approximately 100,000-160,000 hospitalizations and 6,000-10,000 deaths among adults over the age of 65 each year. In this demographic, RSV ranks just behind influenza in terms of severity. When discussing hospitalizations, it’s important to consider not only the clinical seriousness but also how much suffering is required to warrant such an outcome. Many individuals endure severe symptoms at home without reaching the threshold for hospitalization.
Clinical trials leading to FDA approval for the first two RSV vaccines produced the following results:
For Pfizer’s Abrysvo, tested on 34,000 participants:
– 90 percent effective against severe lower respiratory infections caused by RSV, such as pneumonia and bronchitis.
– Protection remained strong, at 79 percent, through the second year post-vaccination.
– 67 percent effective against any RSV infection, including mild cases.
For GSK’s Arexvy, tested on 25,000 participants:
– 94 percent effective against severe RSV-related lower respiratory infections, with 82 percent efficacy against less severe cases.
– 70 percent effective against RSV infections of any severity, including mild illness.
– Broken down by season, the vaccine’s overall efficacy was 82 percent in the first season, 77 percent mid-season, and 67 percent after two seasons. Its efficacy against severe disease was 94.1 percent in the first season, 84 percent mid-season, and 79 percent over two seasons.
Regrettably, the trials did not include enough high-risk individuals or those aged over 75-80 to perform subgroup analyses. For example, the average age in Pfizer’s study was 68. Last year, I noted that we would have to wait and see how the vaccines performed in populations over 80 and whether adverse events were more common, as per mccormickmd.substack.com.
Finally, a note on GBS. The baseline incidence of GBS in the general population is 1-3 cases per 100,000 annually. In Pfizer’s Abrysvo trial, however, we observed 3 cases in just 20,000 participants, translating to 15 cases per 100,000. Were these numbers replicated in real-world data last season?