Coronaviruses are a group of related Ribonucleic acid (RNA) viruses that belongs to the Coronaviridae family (and the order Nidovirales) and widely disseminated in human beings (Huang et al., 2020). Most of the coronavirus infections in human have mild symptoms. The outbreaks of the two other coronaviruses (known as beta-coronaviruses), which include severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), have caused more than 10,000 cumulative cases in the past two decades, with the death rates of about 10% for SARS-CoV and 37% for MERS-CoV (Huang et al., 2020). The novel coronavirus disease 2019 (named COVID-19) started in Wuhan, Hubei province of China and spread worldwide, have been declared a Public Health Emergency of International Concern by the WHO on January 30, 2020 (WHO, 2020a), and later named the 1st pandemic caused by coronaviruses on March 11, 2020 (WHO, 2020b). As of June 3, 2020, COVID-19 affected over 6.5 million people with more than 386000 fatalities worldwide (WHO, 2020c).
Nigeria has reported its first (imported) case of COVID-19 on February 27, 2020 following the case definition by the NCDC (NCDC, 2020; Ohia, 2020). After which community transmission takes place due to inadequate contacts tracing from index case and lack of early closure of boarders to prevent further spread. The fact that the control of COVID-19 pandemic rely heavily on a country’s health care system. Nigeria is currently witnessing a rapid increase of COVID-19 cases probably due to the poor health care system, making it more vulnerable to the virus especially with population of over 200 million people (the highest in Africa). In northern region, Kano state has confirmed its first case of COVID-19 on April 11, 2020 (NCDC, 2020), and since then there might have been issues of under-ascertainment that exists roughly from 22 to 27 April 2020. This is likely due to the lack of sufficient health care facilities (such as test kits, gowns, and facemasks), limited diagnostic testing of suspected patients, and some other unknown reasons. Being the commercial center and the most populace state in Nigeria (with more than 10 million people), Kano is likely the most vulnerable for COVID-19 in northern Nigeria (Gilbert, 2020). As of June 3, 2020, there have been 970 cases of COVID-19 infections confirmed in Kano, Nigeria including 45 deaths (NCDC, 2020). Further the fact that few COVID-19 diagnostic testing was done in Nigeria. In particular, As of May 26, 2020 only about 69,801 people were tested throughout the country (NCDC, 2020). This together with the fact that autopsies and testing of deceased individuals are not generally carried out in the country (in some cases, for traditional or religious reasons), clearly suggests a gross under-ascertainment of the true scenario of the pandemic in the country.
Recently, there were numerous researches focusing on mathematical and statistical modelling to study the dynamics transmission of COVID-19 pandemic since its emergence in Wuhan, China (Li, 2020; Zhao et al., 2020a; Zhao et al., 2020b; Ngonghala et al., 2020; Eikenberry et al., 2020; Tang et al., 2020; Wu et al., 2020; Musa et al., 2020; Gilbert et al., 2020; Lin et al., 2020). Some of these studies focused on estimation of basic reproduction number by using the serial intervals and intrinsic growth rate (Zhao et al.,2020a; Zhao et al., 2020b) or using ordinary differential equations and Markov Chain Monte Carlo methods (Ngonghala et al., 2020; Eikenberry et al., 2020; Tang et al., 2020; Lin, 2020). However, few studies have been done to understand the transmission of COVID-19 pandemic in Africa (Gilbert et al., 2020; Musa et al., 2020).
In this study, we aim to investigate the epidemiological patterns, and estimate the number of under-ascertainment cases and of the COVID-19 outbreak in Kano, Nigeria. We hope our results in this study will be useful to inform the world community of the under-ascertainment issues and the value of in order to help to curtail the spread of the virus. In addition, our study will make a short-term forecast of COVID-19 cases in order to predict possible scenario and informed decision makers in the country about the importance of sustaining stringent measures as recommended by the WHO and other health related organizations as the virus is yet to have effective treatment or vaccination. All measures are currently directed primarily to non-pharmaceutical interventions (NPIs), like social (physical) distancing, community lockdown, quarantine of suspected cases, contact tracing, isolation of confirmed cases and the use of facemasks in general public.