As RSV vaccines near, CID study details RSV prevalence and outcomes in hospitalized adults
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While respiratory syncytial virus is a frequent cause of severe respiratory illness in adults, there’s less awareness of RSV in adults among the public and health care providers. Emily Toth Martin, PhD, MPH, associate professor of epidemiology at the University of Michigan School of Public Health, recently answered several questions from Science Speaks about her recent study in Clinical Infectious Diseases, which characterized the frequency and clinical severity of RSV compared to influenza among hospitalized adults. With two RSV vaccine candidates for older adults nearing regulatory approval in the U.S. and several others also under development, the study findings may help inform future vaccination strategies.
What does this study add to our understanding of the impact of RSV among adults? What are the key findings?
Our study looked at RSV hospitalizations across multiple years in hospitals located across the U.S. By using samples collected for a prospective surveillance program, we identified cases in individuals who may not have been tested clinically for RSV. These individuals often experienced illnesses that were at least or more severe than patients with influenza. Patients with RSV more frequently had a hospital stay exceeding one week and more frequently required mechanical ventilation. These adults also had higher levels of pre-existing chronic conditions. Our study, which has a large sample size and representation from multiple centers across the U.S., confirms similar findings from earlier studies.
What do these findings suggest about the use of newly developed RSV vaccines among adults for prevention?
We found that 6% of respiratory illness hospitalizations in adults during the winter season were due to RSV. When extended to the many hospitalizations across the U.S., an effective vaccine could avert a substantial number of admissions. Interestingly, 30% of the identified RSV cases were between 50 and 64 years old, providing a reason to vaccinate against RSV for the whole age range that is approved, especially individuals with chronic conditions.
Why is our understanding of the impact of RSV in adults more limited compared to what we know about the disease in children?
Some of our gaps in knowledge about RSV in adults is driven by clinical testing. Until recently, it was much more common to see RSV testing in pediatric settings than for adults, but that trend seems to be shifting. Although we still do not have targeted treatments for RSV, continued support for clinical testing of RSV will be important to understand the impact of new vaccines going forward.
Is there anything else you would like to highlight about this study or its implications or about RSV in general?
Chronic health conditions were common among those with RSV, and this was true more than what we saw with influenza in the same study. Charlson score and overall frailty were higher among participants with RSV and cardiopulmonary risk factors including congestive heart failure or COPD were more common. We were not able to determine the overall risk of RSV in people with these conditions. This is an important area for future consideration when developing preventative strategies for RSV.
What should future research in this area focus on? What are other important questions still to be answered?
I hope this research will provide a helpful baseline to support future work on the real-world effectiveness of the upcoming RSV vaccines. An important future question will be whether the vaccine will work through prevention of infection or through a reduction in the severity of disease. In both cases, though, this would be good news for reducing hospitalizations.
Read the full study on the CID website.
