Circulation and seasonality of influenza viruses in different transmission zones in Africa from 2013-2019 

Background: The Influenza Viruses are responsible for more than 5 million of severe cases and 290,000 to 650,000 deaths every year worldwide. Developing countries support 99% of deaths caused by Influenza in children under age of 5. This paper aims to determine the dynamics of influenza viruses in African transmission areas to identify regional seasonality for appropriate decision making and development of regional preparedness and response strategies. Methods: : We used data from the FluMart website collected by Influenza national programs for seven periods of transmission (2013-2019). We calculate the weekly proportions of positive influenza cases and follow the trend of the transmission in countries in the Africa continent to determine the seasonality. Results: : Over the period, Influenza A(H1N1) pdm 2009, A(H3N2), A(H5N1) viruses, as well as influenza B Victoria and Yamagata lineages identified circulated in the African regions. A(H1N1) pdm 2009 and A(H3N2) were highly circulated in northern and southern Africa. Influenza activity follows an annual and regional variation. In the tropical band, from the easter to the western via the middle, influenza activity is marked by the predominance of A subtypes despite the strong circulation of all B lineages. In the southern and northern Africa, only season has been identified for both regions. In the Eastern, four influenza seasons are differentiated and three for the Western part. Conclusions: : The circulating dynamic generates five periods of intense activity during the seasons, so five types of prevention zone. Particularly the tropical band, which is a mixing zone for all influenza viruses, seasons start in the Eastern to end in the Western. Health authorities from countries with same seasons, will need to implement concerted preparedness and control activities.