Empirical Modelling of Confirmed Covid-19 Cases in Nigeria: Forecasts and Implications

Abstract

The world greeted the New Year 2020 with varying degrees of optimism. Overall, forecasts for 2020 were made with cautious optimism given the global slowdown in 2019. While at this, the Chinese city of Wuhan was being ravaged by a deadly severe acute respiratory syndrome coronavirus (SARS-CoV-2), which caused the 2019-nCoV or COVID-19 disease. The disease described by the World Health Organisation as a pandemic has dealt a severe blow on the health system and economic activities on a global scale. Substantial uncertainties surround the appreciation of the precise nature of the health challenge, its spread over time and other aspects all of which further complicate the deployment of appropriate measures in clinical interventions as well as dampen the effectiveness of broader macroeconomic policies especially for the developing countries with their multifarious structural weaknesses. This paper explored the nature of the COVID-19 both in terms of the shape of its growth curve and then estimated the basic reproduction number on the one hand, while also providing forecast of the path of the pandemic, particularly the number of infections for Nigeria. The Poisson, Negative Binomial and Wallinga and Teunis (2004) modelling techniques were used on data from Nigeria. As at April 28, 2020, the COVID-19 curve for Nigeria was upward sloping in nature with the steepness becoming marked from around 30 March 2020. This was about the same period that government ordered the lockdown of the epicentres of the pandemic. Also, the basic reproduction number was both time variant and relatively high for the national (2.25) and subnational [Lagos (3.44) and Abuja (2.77)] cases. The projections from the two standard models suggested that the incidence of infections may just begin to taper off by the end of the second quarter before stabilising at about the third quarter of 2020. This is suggestive of huge trade-offs with respect to losses in potential GDP and thereby of the need for government and other stakeholders to come up with proactive steps to mitigate the severity and reduce the duration of the imminent economic recession that will culminate.