RSV disease burden in older adults is greater than previously thought in the U.S. and other high-income countries, according to industry-funded studies.

Noting that RSV-associated acute respiratory infection (ARI) is an underrecognized cause of illness in older adults, authors of a report published in the International Society for Influenza and other Respiratory Virus Diseases conducted a systematic literature review and meta-analysis to better understand the effects.

The researchers gathered data on RSV-ARI and related hospitalization attack rates and in-hospital case fatality rates (hCFR) in adults aged 60 years or older from the U.S., Canada, European countries, Japan, and South Korea. To do so, they conducted a systematic literature from January 1, 2000, to November 3, 2021, or via other methods (citation search, unpublished studies cited by a previous meta-analysis, gray literature, and an RSV-specific abstract booklet). The study team then performed a random effects meta-analysis on estimates from the included studies.

Ultimately, 21 studies were included in the meta-analysis. The researchers determined, based on pooled estimates, the following risks:

• 1.62% (95% CI: 0.84-3.08) for RSV-ARI attack rate
• 0.15% (95% CI: 0.09-0.22) for hospitalization attack rate
• 7.13% (95% CI: 5.40-9.36) for hCFR.

“In 2019, this would translate into approximately 5.2 million cases, 470,000 hospitalizations, and 33,000 in-hospital deaths in ≥60-year-old adults in high-income countries,” the authors wrote.

“RSV disease burden in adults aged ≥60 years in high-income countries is higher than previously estimated, highlighting the need for RSV prophylaxis in this age group,” the researchers concluded.

An FDA advisory panel recently recommended two vaccines to become the first to be approved to protect against RSV in older adults. The final decision will be made by the FDA over the next few months.

The FDA has said that RSV contributes to more than 10,000 deaths a year among people aged older than 65 years, plus at least 60,000 hospitalizations.

Another recent industry study published in Clinical Infectious Diseases modeled the epidemiology of RSV in the U.S., with a special focus on adults aged 60 years and older with and without vaccination.

“In the absence of a vaccine, we project 17.5-22.6 million symptomatic RSV ARI cases per year in ≥18-year-olds in the U.S., with 3.6-4.8 million/year occurring in ≥60-year-olds,” according to the authors. “Modelling indicates that up to 2.0 million symptomatic RSV ARI cases per year could be prevented in ≥60-year-olds with a hypothetical vaccine (70% vaccine efficacy against symptomatic ARI, and 60% vaccine coverage), and up to 0.69 million cases per year can be prevented in the non-vaccinated population, assuming 50% vaccine impact on infectiousness.”

A third study in Infectious Disease and Therapy demonstrated how the burden of RSV in adults aged older than 60 years might be greatly underestimated, at least partly because there are low levels of RSV testing among adults hospitalized for lower respiratory tract infection (LRTI) in the U.S.

“Without RSV-specific treatment for adults, testing is uncommon, leading to potential underestimation of RSV incidence in real-world data studies,” according to the researchers who sought to quantify the frequency of RSV testing during LRTI-related hospitalizations of older adults to help interpret incidence estimates.

To do that, they used administrative and billing data for hospitalizations of adults aged 65 years or older with a primary or secondary diagnosis of LRTI during the 2016-2019 RSV seasons (October-April), extracting data from the U.S. all-payer Premier Healthcare Database.

The results indicated that most of the 937 study hospitals performed RSV testing infrequently during LRTI hospitalization. In fact, the median percentage of LRTI hospitalizations with RSV testing was 4.3%, and 78.4% of hospitals performed RSV testing in less than 25% of LRTI-related hospitalizations.

They add that RSV testing varied by hospital type. Median percentage tested was significantly higher for:

• Hospitals with ≥200 beds (9.1%) versus <200 beds (1.6%)
• For teaching (11.0%) versus nonteaching (2.5%) hospitals
• In urban (7.4%) versus rural (0.7%) settings.

The authors pointed out that the median percentage of RSV testing increased over time, from 0.8% to 6.3% between the 2016/17 and 2018/19 seasons.

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