RSV Vaccine Effective in Preventing Hospitalization: Retrospective Analysis

A cross-sectional study aimed to assess the burden of respiratory syncytial virus (RSV)-associated hospitalizations in the United States before the introduction of the RSV vaccine in 2023. The study was published in JAMA Network Open and was led by Fiona P. Havers, MD.

The objectives were to describe the demographic characteristics of adult hospitalized with laboratory-confirmed RSV and to estimate annual rates and numbers of RSV-associated hospitalizations, intensive care unit (ICU) admissions, and in-hospital deaths.

Data from the RSV Hospitalization Surveillance Network (RSV-NET), a population-based surveillance platform that captured RSV-associated hospitalizations in 58 counties and 12 states–accounting for approximately 8% of the US population–was used and spanned seven surveillance seasons including 2016-2017 to 2022-2023.

Cases included were nonpregnant hospitalized adults aged 18 years or older residing in the surveillance catchment area with a positive laboratory-confirmed RSV test result within 14 days before or during hospitalization.

Rates were presented per 100,000 adults aged 18 years or older; differences in age group-specific rates were compared using χ² tests. A two-tailed P<.05 was considered statistically significant. Data analyses were conducted using SAS, version 9.4 (SAS Institute Inc).

Results

From the 2016-2017 through the 2022-2023 RSV seasons, there were 16,575 RSV-associated hospitalizations in adults (median interquartile range age, 70 [58-81] years; 9,641 women [58.2%]).

Excluding the 2020-2021 and the 2021-2022 seasons, when the COVID-19 pandemic affected RSV circulation, hospitalization rates ranged from 48.9 (95% CI, 33.4-91.5) per 100,000 adults in 2016-2017 to 76.2 (95% CI, 55.2-122.7) per 100,000 adults in 2017-2018.

Rates were lowest among adults aged 18-49 years (8.6; 95% CI, 5.7-16.8) per 100,000 adults in 2016-2017 to 13.1 (95% CI, 11.0-16.1) per 100,000 adults in 2022-2023 and highest among adults 75 years or older (244.7; 95% CI, 207.9-297.3) per 100,000 adults in 2022-2023 to 411.4 (95% CI, 292.1-695.4) per 100,000 adults in 2017-2018.

Annual hospitalization estimates ranged from 123,000 (95% CI, 84,000-230,000) in 2016-2017 to 193,000 (95% CI, 140,000-311,000) in 2017-2018. Annual ICU admission estimates ranged from 24,400 (95% CI, 16,700-44,800) to 34,900 (95% CI, 25,500-55,600) for the same seasons.

Estimated annual in-hospital deaths ranged from 4,680 (95% CI, 3,570-6,820) in 2018-2019 to 8620 (95% CI, 6,220-14,090) in 2017-2018.

Adults 75 years or older accounted for 45.6% (range, 43.1%-48.8%) of all RSV-associated hospitalizations, 38.6% (range, 36.7%-41.0%) of all ICU admissions, and 58.7% (range, 51.9%-67.1%) of all in-hospital deaths.

In this cross-sectional study of adults hospitalized with RSV before the 2023 introduction of RSV vaccines, RSV was associated with substantial burden of hospitalizations, ICU admissions, and in-hospital deaths in adults, with the highest rates occurring in adults 75 years or older.

“Given the large numbers of potentially vaccine-preventable hospitalizations and deaths associated with RSV, increasing vaccine coverage among adults at highest risk could reduce associated hospitalizations and severe clinical outcomes,” the researchers concluded.