December 03, 2013
1 min read

RSV milder than flu in older adults

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Although respiratory syncytial virus is common in older adults, it appears to be a milder illness than influenza, researchers from Marshfield Clinic Research Foundation have found.

“RSV appears to cause milder illness than influenza in this population, although RSV disproportionately affected the oldest age groups compared to influenza,” the researchers wrote in Clinical Infectious Diseases. “A greater understanding of factors triggering severe RSV disease in older populations will require further study of immunosenescence and other host factors.”

The researchers analyzed nasopharyngeal swabs from patients aged at least 50 years who had acute respiratory illness and were recruited for studies of influenza vaccine effectiveness. The swabs were tested for RSV, and clinical data on the patients were obtained from medical records. The mean age of the patients was 64.2 years, and the mean interval from illness onset to sample collection was 4 days.

Among the 2,225 samples tested from 2004 to 2010, a single respiratory virus was found in half. The most common virus was influenza (17%), followed by human rhinovirus (10%) and RSV (8%). The RSV samples were divided equally between RSV A and RSV B. In multivariate analyses, older age, cough, nasal congestion and wheezing were significantly associated with RSV.

Compared with influenza, RSV was associated with older age and longer interval from illness onset to clinical encounter. Fewer people with RSV were admitted to the hospital within 30 days after illness onset vs. those with influenza.

“Other studies have identified congestive heart failure and chronic pulmonary disease as risk factors for severe RSV illness in older adults,” the researchers wrote. “These conditions were not associated with RSV in our community cohort of adults aged 50 and older with mostly outpatient illness.”

Disclosure: The researchers report no relevant financial disclosures.