Review of global influenza circulation, late 2019 to 2020, and the impact of the COVID-19 pandemic on influenza circulation

Overview

This report summarizes the chronology, epidemiology and virology of influenza seasons between the end of 2019 and the end of 2020 in the temperate regions of the northern and southern hemispheres and the tropical and equatorial regions. Data on influenza activity during this period were derived primarily from reports published by national ministries of health and other official bodies and data reported to WHO through FluNet or FluID. Transmission characteristics, illness and mortality are presented by influenza transmission zone in each temperate hemisphere and in the tropical zone. A small literature review was conducted on possible interactions between respiratory viruses to make hypotheses on the impact of COVID-19 on influenza circulation in 2020.