Photo Credit: EyeEm Mobile GmbH

Fiona P. Havers, MD, MHS, spoke with Physician’s Weekly about managing RSV as a newly vaccine-preventable disease now that multiple vaccines have been approved.

There are three FDA-approved RSV vaccines for adults, all of which have proven effective for preventing severe RSV-related respiratory illness. However, the impact of these vaccines on the prevalence of RSV and associated burdens is not yet clear.

Some data indicate that the general public may be taking RSV less seriously, even though it is still a major cause of mortality and hospitalizations, especially in older adults.

With this in mind, Fiona P. Havers, MD, MHS, and colleagues performed a cross-sectional surveillance study to evaluate how introducing vaccines has changed disease burden. Physician’s Weekly (PW) spoke with Dr. Havers about her team’s findings.

PW: Why was it important to do this study?

Dr. Havers: This study includes the first comprehensive estimates from the CDC of RSV disease burden in adults in the US, including hospitalizations and in-hospital deaths from October 2016 through September 2023 (excluding 2020-2021 and 2021-2022 RSV seasons). Covering multiple recent RSV seasons, it demonstrates that RSV caused a substantial burden of disease in adults, particularly among older adults, before the availability of RSV vaccines. These estimates help us understand who is at increased risk for severe RSV and, thus, most likely to benefit from RSV vaccination.

Can you describe your research and the primary results?

An analysis of RSV seasons from October 2016 through September 2023, excluding 2020-2021 and 2021-2022 RSV seasons, found that RSV caused an estimated 120,000 to 190,000 hospitalizations, 24,000 to 35,000 ICU admissions, and 5,000 to 9,000 in-hospital deaths in adults aged 18 and older, annually. Adults aged 60 and older account for 100,000-150,000 of these hospitalizations each year. The risk of severe RSV increases with age, with adults ages 75 and older experiencing a significantly larger portion of the disease burden compared to other age groups.

Has vaccination reduced the prevalence of severe RSV?

Last year, RSV vaccines reduced the risk for RSV-associated hospitalization by 75% in adults aged 60 and older compared to those who did not receive a vaccine. However, although RSV vaccines were likely effective in preventing hospitalizations in those who received them, overall, RSV disease burden in older adults may not have been substantially impacted due to the relatively low uptake in the 2023-2024 season. As of spring 2024, 20% to 25% of U.S. adults aged 60 years and older were estimated to have received an RSV vaccine. This study did not directly examine the impact of RSV vaccines, but the CDC will continue to use RSV hospitalization data to monitor the impact of vaccines on the prevalence of severe RSV illness.

Are symptoms different in breakthrough infections? 

A vaccine breakthrough infection happens when a vaccinated person gets infected with a virus. RSV vaccines for older adults were developed to prevent severe RSV-associated illnesses, including hospitalizations, ICU admissions, and deaths. CDC continues to study whether those patients who received the vaccine but still became infected with RSV had milder symptoms compared to those who were vaccinated, but because these vaccines have only been available for a single season thus far, there is not yet data available on this. The RSV vaccine is not currently an annual vaccine. Protection from an RSV vaccine lasts more than one year. This means that if someone has already received an RSV vaccine, they should not get another RSV vaccine at this time.

Have attitudes about RSV changed with the introduction of vaccines?

Before the availability of vaccines, many people, including doctors, were not aware that RSV can cause serious illness in adults. This study showed that between 123,000 and 193,000 adults are hospitalized in the US for RSV every year. Effective vaccines are now available to prevent severe illness. This has raised awareness of RSV as a disease that affects adults, but the relatively low uptake of the vaccine last year indicates that there is more to be done to raise awareness of both RSV and the availability of RSV vaccines to protect eligible patients.

Is there anything else you’d like to mention?

Doctors should be aware of the CDC’s recommendations for an RSV vaccine for all adults ages 75 years and older and for adults ages 60–74 years who are at increased risk of severe RSV. The RSV vaccine is not currently an annual vaccine, meaning eligible adults do not need to get a dose every RSV season. Currently, the CDC recommends only a single dose of RSV vaccine for all adults ages 75 and older and for adults ages 60–74 with increased risk of severe RSV disease. Additional surveillance and evaluation activities are ongoing to determine whether adults might benefit from receiving additional RSV vaccine doses in the future.