Viral etiology of 363 elderly people with influenza-like illness and severe acute respiratory infections in Pudong New Area, Shanghai

Objective To understand the epidemiological characteristics of common respiratory viruses among influenza-like illness (ILI) and severe acute respiratory infections (SARI) in Pudong New Area, Shanghai, so as to help estimate the disease burden and conduct the valuable control strategies. Methods Respiratory specimen (throat swab or sputum) from cases older than 65 years old with ILI/SARI were collected from outpatient and inpatient settings in four sentinel hospitals in Pudong New Area. Each specimen was tested by multiplex PCR for eight target viral etiologies, including influenza virus, human rhinoviruses (HRV), human para-influenza virus (PIV), adenoviruses (ADV), respiratory syncytial virus (RSV), human metapneumovirus (hMPV), human coronavirus (hCoV) and human bocavirus (hBoV).Chi-square tests or Fisher's Exact Test were used to compare and analyze. Results From January 1st, 2014 to June 30st, 2016, a total of 363 elderly cases with ILI/SARI were enrolled, with 202 (55.65%) male and a median age of 70 years old. 142(39.12%) patients were detected positive for any one of the eight viruses. Influenza was the predominant virus (20.94%, 76/363), with the positive proportion of (29.83%) among ILI cases and (12.09%) among SARI cases. The Influenza infection presented two seasonal peaks in winter (December to February) and summer (July to September). Conclusion Influenza is identified as the leading viral pathogen both among ILI and SARI cases older than 65 years old, and two seasonal epidemic peaks areobserved in Shanghai. Influenza vaccination strategy should be advocated for the elderly population in Shanghai.