Low interim influenza vaccine effectiveness, Australia, 1 May to 24 September 2017

Abstract

In 2017, influenza seasonal activity was high in the southern hemisphere. We present interim influenza vaccine effectiveness (VE) estimates from Australia. Adjusted VE was low overall at 33% (95% confidence interval (CI): 17 to 46), 50% (95% CI: 8 to 74) for A(H1)pdm09, 10% (95% CI: -16 to 31) for A(H3) and 57% (95% CI: 41 to 69) for influenza B. For A(H3), VE was poorer for those vaccinated in the current and prior seasons.

Prediction of influenza vaccine effectiveness for the influenza season 2017/18 in the US

“…This result suggests that vaccine would not be efficient against majority of Australian H3N2 viruses in the flu season 2017. This conclusion is in accord with reported low VE of influenza vaccine in Australia in 2017 flu season 2 .…”

“…This result suggests that VE, at least in the beginning of this flu season will not be suboptimal in the US 2 . As for the prediction of VE in Australia, this could change during the flu season if some of the viruses from the small cluster would emerge.…”

“…Low VE of influenza vaccine in Australia prompts the US and the European health authorities to prepare for the severe influenza season 2017/2018 with suboptimal VE on the Northern hemisphere 2 . On the other hand, there are no data or reported analysis of H3N2 viruses circulating in US in 2017 that would allow to predict the VE for the next flu season.…”

“…In the 2017, flu season in Australia VE was only 10% 2 , which resulted in very high numbers of hospitalization and deaths among vaccinated patients. Most vulnerable was the elderly population of patients (>65 years).…”

“…Most vulnerable was the elderly population of patients (>65 years). This low VE was ascribed to variability of the H3N2 influenza viruses that were dominant in Australia that season 2 .…”