A new international study emphasized the growing need for a vaccine and the adoption of prevention strategies to reduce the burden of RSV disease in older adults.

The authors pointed out in the journal Open Forum Infectious Diseases that RSV is a significant cause of disease burden in older adults, whether they are community-dwelling (CD) or live in long-term care facilities (LTCFs).

“Despite the observed low severity of cRSV-ARI [confirmed RSV-acute respiratory infection], our results support the need for RSV prevention strategies among adults ≥50 years old,” the authors wrote.

The data on RSV disease burden in adults “remain scarce,” leading to a prospective cohort study covering two RSV seasons (Season 1: October 2019-March 2020 and Season 2: October 2020-June 2021). RSV-ARIs were identified through active surveillance, in medically stable CD adults aged 50 years and older in Europe or adults aged 65 years and older in LTCFs in both Europe and the United States. Polymerase chain reaction from combined nasal and throat swabs was used to confirm RSV infection.

The analysis included 1,251 adults in CD and 664 LTCFs in Season 1 and 1,223 adults in CD and 494 in LTCFs for Season 2. The researchers report that, during Season 1, overall incidence rates ([IRs] cases/1,000 person-years) and attack rates (ARs) for cRSV-ARIs were 37.25 (95% CI, 22.62-61.35) and 1.84% in adults in CD and 47.85 (CI, 22.58-101.4) and 2.26% in adults in LTCFs. Complications occurred for 17.4% (CD) and 13.3% (LTCFs) of cRSV-ARIs, while one cRSV-ARI occurred in Season 2 (IR = 2.91; CI 0.40-20.97; AR = .20%), without complications.

They added that no cRSV-ARIs led to hospitalization or death, although viral pathogens were codetected in ≤17.4% of cRSV-ARIs.

Background information in the study pointed out that human RSV is an RNA virus of the family Pneumoviridae, and “two antigenically distinct subtypes (RSV-A and RSV-B) exist and cocirculate with alternating dominance but without any clear pattern.”

Detection is difficult, the researchers wrote, because the clinical symptoms of RSV infection are not specific in adults and differentiation from other respiratory pathogens is challenging without laboratory confirmation. Furthermore, they advised, virus titers in respiratory secretions are usually lower in adults compared with children and shedding is of shorter duration. Infections tend to start with mild symptoms leading to delays in seeking medical advice and less likelihood of testing positive for RSV.

“Therefore, the burden of RSV infection continues to be underestimated in the older adult population,” the authors wrote, adding, “Still, RSV is increasingly recognized as an important pathogen in adults because it can lead to severe lower respiratory tract disease in patients with comorbidities (in particular, immunocompromised adults and those with cardiopulmonary conditions) and in older adults, due to immunosenescence.”

Cases also are rapidly increasing—rising globally from 1.5 million in 2015 to 5.2 million in 2019. In-hospital deaths more than doubled from 14,000 to 33,000, the study pointed out.

“Knowing the true burden of RSV disease in the general adult population and in older adults is crucial in the evaluation and future implementation of novel antiviral agents for treatment and vaccines for prevention of RSV, which are currently under development,” the study concluded.

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