Certain variables used in influenza-like illness surveillance may lead to the underestimation of RSV incidence among adults, according to results published in the International Journal of Infectious Diseases. Giancarlo Icardi, MD, and colleagues used influenza-like illness surveillance to analyze samples for influenza, RSV, and other respiratory illnesses. Among 1,240 adults tested with influenza-like illness surveillance, researchers identified RSV in 5.2% of cases. The prevalence of fever/feverishness was significantly lower (83.3%) in individuals who tested positive for RSV and negative for both viruses (79.4%) than in patients positive for influenza (96.2%). Almost all adults positive for RSV—98.3%—reported a cough. Compared with subjects who tested negative, the adjusted relative risk ratio of cough in RSV-positive subjects was much higher than in influenza-positive subjects (6.89 vs 2.79). Using acute respiratory illness with cough as the RSV case definition increased specificity
