A study analyzing data from October 2016 to September 2023 revealed a significant caseload. respiratory syncytial virus (RSV) 2023 was seen in hospitalized US adults before the availability of RSV vaccines; This suggests that increasing RSV vaccination among older adults may help reduce serious clinical outcomes and healthcare burdens.¹

Researchers believe the findings highlight the significant burden of RSV in the older adult population before vaccines became available. | Image source: angellodeco – Stock.adobe.com

The cross-sectional study was published at: JAMA Network Open.

“This analysis used 2016 to 2023 data from the population-based RSV Hospitalization Surveillance Network (RSV-NET) to describe the demographic characteristics of adults 18 years of age and older hospitalized with laboratory-confirmed RSV and to estimate the rates and numbers of RSV-related hospitalizations , intensive care unit (ICU) admissions, and in-hospital deaths,” the study researchers wrote.

On June 26, 2024, the CDC’s Advisory Committee on Immunization Practices (ACIP) updated its recommendations that all adults age 75 and older and adults age 60 to 74 who are at increased risk for severe RSV should receive a single dose of RSV vaccine. Arexvy (GSK), Abrysvo (Pfizer) or mResvia (Moderna)).²

RESP-NET conducts population-based surveillance of hospitalizations for RSV, COVID-19, and influenza in the United States.¹ The data captured laboratory-confirmed RSV-related hospitalizations in 58 counties in 12 states, covering approximately 8% of the U.S. population. Eligible participants included nonpregnant adults 18 years of age or older who tested positive for RSV during hospitalization or within the previous 14 days.

The primary outcome of the study was the burden of RSV in US adults, as measured by rates of RSV-related hospitalization, intensive care unit admission, and in-hospital mortality.

The study identified a total of 16,575 laboratory-confirmed RSV-related hospitalizations between the 2016-2017 and 2022-2023 RSV seasons; reverse transcription polymerase chain reaction (RT-PCR) was the primary diagnostic test (98.7%). Additionally, a significant majority of the patients (62.6%) were 65 years of age or older.

Hospitalization rates peak in January each year and there have been significant disruptions during the COVID-19 pandemic. 19.1% of cases were admitted to the intensive care unit and 4.3% of patients died in hospital; The highest mortality rate (5.8%) was observed in adults aged 75 years and older.

Testing practices have improved over time, with the rate of adults hospitalized rising from 30.4% in 2016-2017 to over 60% in 2022-2023. While the unadjusted hospitalization rate ranged from 8.8 to 21.2 per 100,000 adults, adjusted rates varied significantly by age, peaking among adults 75 and older. The estimated number of annual RSV-related hospitalizations ranged from 123,000 in 2016-2017 to 193,000 in 2017-2018; ICU admissions and in-hospital deaths also show a significant burden.

Older adults, particularly those age 75 and older, had the most severe outcomes, representing 45.6% of hospitalizations, 38.6% of intensive care unit admissions, and 58.7% of in-hospital deaths.

But the researchers also acknowledged some limitations. First, RSV testing relied on clinician discretion, potentially leading to an underestimation of the true RSV burden. Although adjustments have been made for test practices and test sensitivity, the underlying assumptions may be incorrect. Therefore, load estimates may be biased. Additionally, the analysis did not include nonrespiratory complications of RSV or evaluate primary causes of hospitalization. Finally, RSV-NET data may not be fully generalizable to the entire US population.

Despite these limitations, researchers believe the findings underscore the significant burden of RSV in the older adult population before the vaccine was introduced.

“The study found that the majority of hospitalizations occurred among older adults, with the highest hospitalization rates occurring in people age 75 and older,” the researchers wrote. “Given the large number of potentially vaccine-preventable hospitalizations and deaths associated with RSV, increasing vaccine coverage among adults at highest risk may reduce associated hospitalizations and serious clinical outcomes.”

References

1. Havers FP, Whitaker M, Melgar M, et al. Burden of respiratory syncytial virus-associated hospitalizations in US adults, October 2016 to September 2023. JAMA Netw On. 2024;7(11):e2444756. doi:10.1001/jamanetworkopen.2024.44756

2. Steinzor P. FDA approves Abrysvo RSV vaccine for high-risk adults. AJMC. 23 October 2024. Access date: 14 November 2024. https://www.ajmc.com/view/fda-approves-abrysvo-rsv-vaccine-for-adults-at-increased-risk.