Incidence, symptoms and medical care for influenza virus and respiratory syncytial virus illnesses among older adults in Eastern China: Findings from the China Ageing Respiratory Infections Study (CARES), 2015-2017

Abstract

SUMMARYIntroductionFew studies have examined the incidence of virologic-confirmed influenza virus and respiratory syncytial virus (RSV) infections in community-dwelling older adults.MethodsWe enrolled adults aged 60–89 years in Jiangsu Province, China and followed them weekly from December 2015–September 2017 to identify acute respiratory illnesses (ARI), collect illness information and respiratory specimens for laboratory testing.Results1,527 adults were enrolled, 0·4% reported ever receiving influenza vaccination. 95 PCR-confirmed influenza ARIs and 22 RSV ARIs were identified, among whom 4–5% required hospitalization. One death associated with RSV ARI while none for influenza ARIs was observed. From December 2015-August 2016, the cumulative incidences of influenza and RSV ARIs were 0·8% (95% CI:0·3–1·4) and 0·5% (95% CI:0·1–1·0), respectively. From September 2016-August 2017, the cumulative incidences were 6·1% (95% CI:4·7–7·7) and 1·0% (95% CI:0·5–1·6); the influenza and RSV ARI-associated hospitalization incidences were 0·3% (95% CI:0–0·8) and 0·1% (95% CI:0–0·2). Feverishness was more common in influenza (55%) than RSV ARIs (30%, p=0·03). Influenza (12·5 days, p=0·02) and RSV ARI symptoms (14·1 days, p=0·15) lasted longer compared to PCR-negative/other ARIs (11·0 days). Antibiotic use was more common for influenza (65%, p=0·02) and RSV (70%, p=0·04) ARIs than other ARIs (51%).ConclusionsWe observed a higher incidence of influenza relative to RSV infections among community-dwelling older adults compared to prior studies. Our findings suggest older adults may benefit from receiving influenza and RSV vaccines to reduce the occurrence of illnesses.