Study uncovers staggering RSV impact on US adults, with ICU admissions and in-hospital deaths notably high—prompting calls for better testing and vaccine coverage to reduce the severe toll on those most vulnerable.

Study: Burden of Respiratory Syncytial Virus–Associated Hospitalizations in US Adults, October 2016 to September 2023. Image Credit: Jarun Ontakrai / Shutterstock

A study was recently conducted to estimate the prevaccine burden of respiratory syncytial virus (RSV)-related hospitalizations among US adults during the pre-RSV vaccination era. The study is published in JAMA Network Open.

Background

Respiratory syncytial virus (RSV) infections are associated with significant morbidity and mortality among US adults, especially those aged 60 years or above.

The US Centers for Disease Control and Prevention (CDC) recommended a single dose of an RSV vaccine for adults aged 60 years or above in June 2023. These recommendations are scheduled to be updated in June 2024 to provide a single vaccine dose to all adults aged 75 years or above and to adults aged 60 to 74 who are at higher risk of developing severe RSV infections.

Testing for RSV does not come under routine examinations for hospitalized adults with respiratory disease. Limited awareness among healthcare providers of RSV’s relevance to adult populations could be one potential reason behind the lack of testing. Another reason could be that an RSV diagnosis does not generally change the course of clinical treatment.

In this study, scientists quantified the numbers and rates of RSV-related hospitalizations, intensive care unit (ICU) admissions, and in-hospital deaths among US adults aged 18 years or above during the pre-vaccine period.

Study Design

The study analyzed data from the RSV Hospitalization Surveillance Network (RSV-NET), which conducts population-based monitoring of RSV-related hospitalizations in 58 counties across 12 states, covering an estimated 8% of the US population.
The study covered seven surveillance seasons from 2016 to 2023 and included cases of non-pregnant hospitalized adults aged 18 years or above who had a laboratory-confirmed RSV infection during hospitalization or within 14 days before hospitalization.

Age group-specific and overall RSV-related hospitalization rates per 100,000 adults were estimated in the study. Annual numbers of hospitalizations were projected by extrapolating the estimated rates to the US population, with adjustments for RSV test sensitivity and the under-detection of RSV among hospitalized adults with acute respiratory diseases.

Important Observations

During the study period, 16,575 RSV-related hospitalizations among adults were identified. Among these patients, 58% were females, 42% were males, and the median age was 70.

The highest peak in hospitalization rates was observed each January during the study period. A reduced incidence of RSV was observed between 2020 and 2022, which coincided with the coronavirus disease 2019 (COVID-19) pandemic period.

During the entire study period, 19% of patients were admitted to the ICU, and 4.3% died in hospital. The highest number of in-hospital deaths was observed among patients aged 75 years or above.

The seasonal hospitalization rate was 48.9 per 100,000 adults from 2016 to 2017, and it increased to 76.2 per 100,000 adults from 2017 to 2018. The lowest rate of hospitalization was observed among adults aged 18 to 49, and the highest rate was observed among adults aged 75 years and above.

Extrapolation of adjusted hospitalization rates to the US adult population showed that annual hospitalization estimates ranged from 123,000 in 2016-2017 to 193,000 in 2017-2018. For the same periods, annual ICU admission estimates ranged from 24,400 to 34,900.

The estimated annual in-hospital deaths ranged from 4,680 in 2018-2019 to 8,620 in 2017-2018. The majority of disease burden, including RSV-related hospitalizations, ICU admissions, and in-hospital deaths, occurred in adults aged 65 years and above.

Among adults aged 75 years or above, 46% of hospitalizations, 39% of ICU admissions, and 59% of in-hospital deaths occurred. For those aged 65 years or older, the estimated number of hospitalizations was 85,000 in 2016-2017 and 136,000 in 2017-2018.

Study Significance

The study’s analysis of laboratory-confirmed RSV infection-related hospitalizations indicates a notably high burden of severe RSV infection, with an estimated 123,000 to 193,000 hospitalizations, 24,400 to 34,900 ICU admissions, and 4,680 to 8,620 in-hospital deaths occurring annually among US adults.

The study highlights the significant impact of RSV on respiratory disease among adults, especially those aged 65 years or older.

In the US, testing rates for RSV are considerably low among hospitalized adults with acute respiratory disease. The current study shows that less than 50% of hospitalized patients with acute respiratory disease undergo RSV testing.

The authors recommend that both clinicians and patients increase their awareness of RSV infections in adults by promoting multiplex respiratory virus testing and improving RSV vaccine accessibility.

Current evidence confirms that RSV vaccines are effective in preventing hospitalization and death due to the virus. The study advises that increasing vaccine coverage among high-risk adults could help reduce the risk of severe RSV outcomes.