RSV Infections Take Toll on Adults

Approximately 1 in 20 adults with outpatient respiratory syncytial virus (RSV) infections were readmitted to the hospital within 28 days, based on new data from more than 67,000 cases.

RSV remains a top cause of acute respiratory tract infections among adults in the United States, with an estimated 159,000 hospitalizations in those aged 65 years or older, wrote Suzanne N. Landi, MPH, PhD, of Pfizer Inc., New York City, and colleagues in a study published in JAMA Network Open.

“Currently, limited estimates exist to determine the risk of hospitalization following outpatient RSV disease diagnoses in the United States,” said corresponding author Joshua T. Swan, PharmD, MPH, in an interview.

The current study was conducted to inform development of clinical trials, said Swan, senior director and category clinician in internal medicine and disease development at Pfizer, the sponsor of the study. These trials would assess the efficacy of an outpatient RSV antiviral treatment in preventing RSV-related hospitalization within 28 days among adults at a high risk for progression to severe illness, he said.

The authors reviewed data from 67,239 adults aged 18 years or older with medically attended RSV infections between October 1, 2016, and September 30, 2022. The data came from three databases: Optum (2771 patients), TriNetX (7442 patients), and Veradigm Network Electronic Health Record (VNEHR; 57,026 patients).

The primary outcome was all-cause hospitalization within 28 days of medically attended RSV.

Overall, the proportions of patients hospitalized within 28 days of infection were 6.2%, 6.0%, and 4.5% in Optum, TriNetX, and VNEHR databases, respectively.

Approximately two thirds of the patients (62%-67% across the three databases) were women, and 14.0%-54.5% were aged 65 years or older. The researchers also identified comorbidity prevalences of 20.0%-30.5% for chronic obstructive pulmonary disease (COPD), 14.6%-24.4% for congestive heart failure (CHF), and 14.6%-24.4% for asthma.

A majority of the patients (ranging from 74.5% to 90.6% across the three databases) fell into a high-risk subgroup, defined as age 65 years or older with asthma, COPD, and CHF. In this high-risk group, the proportions of hospitalizations were 7.6%, 8.5%, and 6.5% for Optum, TriNetX, and VNEHR, respectively.

The findings were limited by several factors, including the use only of data from outpatient settings, which cannot be used to estimate the RSV burden in the general population, and the reliance only on diagnosis or procedure codes to identify comorbidities, the researchers noted.

However, “The absolute risk of hospitalization of 1 out of 20 patients observed in our study represents significant and meaningful risk for vulnerable adults, in a disease where much of the public’s attention has historically focused on risk of hospitalization for young children,” Swan told Medscape Medical News. “These results highlight the unmet medical need for outpatient interventions and preventive measures that can reduce hospitalizations,” he added.

Don’t Underestimate RSV Impact

The current study highlights the fact that RSV is a major cause of respiratory viral illness, said David R. Manoff, MD, associate professor of clinical thoracic medicine and surgery at Temple University, Philadelphia, in an interview.

“Historically, influenza, and, more recently, COVID-19 infection have generally been thought of as more likely to cause harm and, thus, have been more emphasized in terms of both vaccination and treatment,” said Manoff, who was not involved in the study.

The current study provides new evidence that infection with RSV can be far more serious than often recognized and a major potential source of both hospitalization and morbidity, Manoff told Medscape Medical News. In fact, data published in the Morbidity and Mortality Weekly Report in 2023 showed that the risks of needing oxygen, intensive care unit (ICU) admission, intubation, and death were actually higher in patients hospitalized with RSV infections than in those hospitalized with influenza or COVID-19, he noted. “Understanding which population is hospitalized in the first place is vital to targeting prevention measures,” he added.

The new data are consistent with previous studies showing that most patients with RSV infection have primarily upper respiratory tract infection–type symptoms, but that a minority will develop lower respiratory tract disease, Manoff noted.

The findings add to the argument for implementation of RSV vaccination, especially in high-risk individuals, and support the need for RSV testing when patients present for care, he said.

However, more research is needed to reflect recent numbers, Manoff told Medscape Medical News. The study timeframe of 2016-2022 not only precedes commercially available RSV vaccines but also includes the period of increased isolation and masking seen during the COVID-19 pandemic years of 2020-2021, Manoff explained. “We need to see if the same trends continue in the post-pandemic era,” he said. Additionally, the studies leading to approval of the RSV vaccine showed a reduction in hospitalization with RSV, and it is important to see how this reduction translates in real-world data and whether the RSV vaccines are reducing need for ICU admission, intubation, and death, Manoff said.

The study was funded by Pfizer, and Swan is a Pfizer employee. Manoff had no financial conflicts to disclose.