FluTracking: Weekly online community based surveillance of influenza-like illness in Australia, 2018 Annual Report

Abstract

FluTracking experienced major growth in 2018, with participation numbers increasing 34.1% from 2017. The addition of 16,881 new participants brought the total number of participants for 2018 to 45,532. A majority of participants continued to complete their survey within 24 hours of the email being sent (mean 74.3% responses received in 24 hours). The rate of influenza-like illness (ILI) in 2018 was the lowest since FluTracking commenced in 2007 and was consistently low across all ages. The peak weekly ILI rate was consistent with previous years, occurring during the week ending 19 August. This preceded the peak in laboratory-confirmed influenza notifications by three weeks. During the peak week of FluTracking, 2.1% of unvaccinated, and 1.9% of vaccinated participants reported fever and cough. By the final survey of 2018, 65.6% of participants had received the annual influenza vaccine, compared with 60.2% in 2017. Vaccination rates in participants under five years of age doubled from 23.7% in 2017, to 55.6% in 2018. During the peak four weeks of reported ILI, a lower percentage of participants sought medical care in 2018 compared to 2017 (36.7% and 42.3% respectively), and fewer participants reported a positive laboratory test for influenza (0.8% and 4.8%). Overall the severity of the 2018 season was one of the lowest FluTracking has recorded. Rates of both influenza laboratory notifications and general practitioner (GP) ILI consultations were lower in 2018 than most prior years. We found a reduction in the percentage of FluTracking participants with ILI who were tested for influenza (3.2% compared with 5.0% in 2017), and who visited a medical practitioner (36.7% compared with 42.3% in 2017). The drop in laboratory-confirmed cases and Australian Sentinel Practices Research Network (ASPREN) reported GP consultations concurs with our survey results that 2018 was a milder influenza season than many previous.