Rates of Hospitalizations for Respiratory Syncytial Virus, Human Metapneumovirus, and Influenza Virus in Older Adults

Background. We performed a prospective study to determine the disease burden of respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) in older adults in comparison with influenza virus. Methods. During 3 consecutive winters, we enrolled Davidson County (Nashville, TN) residents aged >= 50 years admitted to 1 of 4 hospitals with acute respiratory illness (ARI). Nasal/throat swabs were tested for influenza, RSV, and HMPV with reverse-transcriptase polymerase chain reaction. Hospitalization rates were calculated. Results. Of 1042 eligible patients, 508 consented to testing. Respiratory syncytial virus was detected in 31 participants (6.1%); HMPV was detected in 23 (4.5%) patients; and influenza was detected in 33 (6.5%) patients. Of those subjects aged >= 65 years, 78% received influenza vaccination. Compared with patients with confirmed influenza, patients with RSV were older and more immunocompromised; patients with HMPV were older, had more cardiovascular disease, were more likely to have received the influenza vaccination, and were less likely to report fever than those with influenza. Over 3 years, average annual rates of hospitalization were 15.01, 9.82, and 11.81 per 10 000 county residents due to RSV, HMPV, and influenza, respectively. Conclusions. In adults aged >= 50 years, hospitalization rates for RSV and HMPV were similar to those associated with influenza.