Pre-RSV Vaccine Era: RSV Severity Matches or Exceeds COVID-19 and Influenza in Hospitalized Patients

Before the vaccine for respiratory syncytial virus (RSV), the virus was as severe as COVID-19 or influenza among unvaccinated patients, but more severe than COVID-19 or influenza among vaccinated patients hospitalized with those diseases, according to a study published in JAMA Network Open.

“We assessed disease severity among adults hospitalized in the US with RSV during the 16 months immediately preceding recommendations by the Advisory Committee on Immunization Practices for RSV vaccine use,” wrote Diya Surie, MD, Coronavirus and Other Respiratory Viruses Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention in Atlanta, Georgia, and coauthors. “To provide context for the observed severity of RSV disease in hospitalized patients, we compared it with the severity of adults hospitalized with COVID-19 and influenza disease, stratified by vaccination status, during the same period,” she added.

Among the 7998 patients positive for RSV, COVID-19, or influenza, hospitalization rates varied: 484 (6.1%) for RSV, 6422 (80.3%) for COVID-19, and 1092 (13.7%) for influenza. Peak hospitalizations for RSV and influenza occurred from November to December 2022, while COVID-19 hospitalizations remained consistently high throughout.

Among patients with RSV, disease severity outcomes, such as the need for advanced respiratory support or death, were comparable to unvaccinated COVID-19 and influenza patients but higher than vaccinated counterparts. For instance, 12.0% of patients with RSV required invasive mechanical ventilation (IMV) or died, compared to 201 (14.1%) of unvaccinated COVID-19 patients and 458 (9.2%) of vaccinated COVID-19 patients. RSV patients were more than twice as likely to receive advanced respiratory support compared to vaccinated COVID-19 (adjusted odds ratio [aOR], 2.03; 95% CI, 1.64-2.51) or influenza patients (aOR, 2.71; 95% CI, 1.89-3.87).

Similar trends were observed among older adults. Additionally, when assessing peak respiratory severity, RSV patients exhibited higher overall severity compared to unvaccinated COVID-19 and influenza patients, and substantially higher severity than vaccinated individuals. RSV subtypes A and B, circulating since early 2020, displayed comparable clinical outcomes. In contrast, COVID-19 patients predominantly had SARS-CoV-2 Omicron lineages, with BA.1 showing the greatest severity. Influenza A(H3N2) was the predominant subtype among influenza patients and exhibited lower or similar severity compared to influenza A(H1N1).

“In this cohort study among adults hospitalized in the US during the 16 months preceding recommendations for the first adult RSV vaccines, RSV disease severity was similar to severity of COVID-19 and influenza disease among unvaccinated patients and substantially higher than COVID-19 and influenza disease among vaccinated patients,” concluded the study authors. “Severity of RSV disease among adults may be important to consider as RSV vaccine policy evolves,” they added.

Reference

Surie D, Yuengling KA, DeCuir J, et al. Severity of respiratory syncytial virus vs COVID-19 and influenza among hospitalized US adults. JAMA Netw Open. 2024;7(4):e244954. doi:10.1001/jamanetworkopen.2024.4954