Since the end of 2019, an outbreak of coronavirus disease 2019 (COVID-19), now a pandemic (2020 (World Health Organization, 2020b; Gilbert, 2020), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (World Health Organization, 2020a) has hit China severely, in particular, the epicenter, Wuhan, the capital city of Hubei province. The city has been locked down since January 23, 2020 and the lockdown has been lifted on April 8, 2020. As of the March 23, the epicenter has moved to Europe and US, after the outbreak was largely controlled in China. Many countries are facing a rapid increasing trend of confirmed cases. The case-fatality-rate varies wildly from country to country. As of 13 April 2020, about 2 million people have been infected with COVID-19 with over 117,000 death globally (out of which about 90% of the death cases were from United State and Europe) (World Health Organization, 2020a; World Health Organization, 2020c).
Africa reported its first case of COVID-19 in Egypt on 14 February 2020 (Gilbert, 2020; World Health Organization, 2020c).
As of 13 April 2020, a total of 15207 infected cases were reported, with 831 fatal cases, giving an overall case fatality rate (CFR) of 5.47% throughout Africa, among them only 3 cases with no death reported in February 2020 (World Health Organization, 2020c).
The African region has been described as one of the most vulnerable with the COVID-19 infection (Gilbert, 2020) in the initial phase, due to the fact that Africa is important commercial partner of China and as a result, large volume of business person travel to the region. Since the epicenter is now in Europe, due to the close tie between Africa and European countries, African countries face even bigger threat.
Several control measures have currently been taken by most of the African countries to prevent/reduce the spread of COVID-19, especially against case importation from the COVID-19 epicenters. Some of the measures includes travel ban to and from the most COVID-19 hit countries, school closures, temporary ban of religious gathering and so on (Gilbert, 2020; World Health Organization, 2020d; Nigeria Center for Disease Control, 2020). Nevertheless, the ability to curtail or reduce and control the local transmission after case importation depends largely with how African government are seriously sustaining the current recommended measures. Due to the fragile health care system, insufficient health workers, lack of water, and sanitizers for maintaining hygiene in the region. African countries need to find their optimal strategies to stop the spread of COVID-19 in its region.
Numerous epidemiological studies have been conducted to understand the transmission dynamics of COVID-19, which is quantified in two key parameters, the basic reproduction number (the expected number of secondary cases that may be caused by a typical primary case during his/her infectious period in a wholly susceptible population, R0) and the serial interval (time delay between the symptom onset of a primary case and his/her secondary case, SI). High reproductive number and short serial interval imply rapid growth. In the initial phase, the epidemic (number of new cases over time) typically exhibited exponential growth. The basic reproduction number is a function of the exponential growth rate (r) and the serial interval. Studies on the basic reproduction number, exponential growth rate and serial interval (Zhao et al., 2020a; Ma, 2020; Nishiura et al., 2020; Du et al, 2020; and Zhao et al., 2020b), many of which have shown the R0 ranges from 2.0 to 4.0, and initial under-reporting/under-detection during the early phases of the outbreak in Wuhan, China.
The aim of this study is to estimate the exponential growth rate and the basic reproduction number the COVID-19 pandemic in Africa at the early stage, which should be valuable in informing the official and public in the preparedness against COVID-19 spread, forecasting the trend, and highlighting the importance of sustaining strict measures in order to curtail the spread.