Co-epidemics: have measures against COVID-19 helped to reduce Lassa fever cases in Nigeria?

While the coronavirus disease 2019 (COVID-19) pandemic has multiple devastating public health and socio-economic effects across the world, Nigeria along with other West African countries is simultaneously faced with a recurrent Lassa fever epidemic. The complicating scenario is the similarity in the clinical manifestation of COVID-19 and Lassa fever, making the misdiagnosis of the initial presentation of both diseases a significant risk with an increased likelihood of co-infection. However, the strict implementation of COVID-19 infection prevention and control measures across Nigeria after the initial outbreaks concurrently resulted in the reduction of Lassa fever cases. The abrupt change in the behaviour of Lassa fever epidemiological data, which are attributable to the implementation of COVID-19 infection prevention and control measures at the national, sub-national and community levels, requires detailed investigation during and after the COVID-19 epidemic to elucidate the interactions and evolutionary dynamics of Lassa fever cases in Nigeria.