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thus covering the first 6 months of the outbreak. This database covered the 54 African countries (classified in the AFRO
zone or in the EMRO zone), as well as two territories located in the Indian Ocean (Reunion and Mayotte). Only one
territory did not declare any case by August 2020: The island of Saint Helena, located in the middle of the Atlantic Ocean,
one of the rare territories to have escaped the Spanish flu pandemic of 1918-1919 because of its geographic isolation
(McSweeny, Colman, Fancourt, et al., 2007).
Demographic data for these countries were taken from the United Nations Population Division database: Population
in 2020, age structure, mortality, fertility, and urbanization (United Nations, 2014; United Nations, 2019). The data on
country area, allowing the calculation of the population density, came from the FAO database (FAO-Stats, 2019). This
was added a database on the geographical distribution of the population, but which does not cover the islands (Linard,
Gilbert, Snow, et al., 2012). The economic data came from the World Bank database (World Bank, 2019), which were
supplemented when necessary by the Index Mundi database (Index Mundi, 2020): GDP per capita in purchasing power
parity and in constant dollars; air traffic (in passengers per million populations).
2.2. Methods

This study links epidemiological parameters to demographic, economic, and public health parameters. The following
indicators were defined:
− Cumulative incidence = Number of cumulative notified cases by August 15, divided by mid-year population (July 01,
2020), expressed in million inhabitants.
− Weekly incidence = Number of cases occurring during the week, from Sunday to Sunday.
− Case fatality = Number of deaths declared/number of cases declared (per 1000 cases).
− The epidemic’s net reproduction rate (R ), also called the “basic reproductive rate” in epidemiology (Anderson and
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May, 1991), was calculated in two ways:
− Weekly R = 2 × Number of cases of the week/Number of cases of the two previous weeks. This calculation is
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justified because the contamination mainly occurs during the 2 weeks following the primary infection.
− R smoothed over the period: It is calculated as the growth rate of the number of weekly cases (r), obtained by
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logarithmic adjustment, and by the average duration between the index and secondary cases (d) = 9 days, according
to the classic formula: R = exp (r × d). The average interval between index and secondary cases was chosen so that
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the two measurements were identical over the same period.
The country characteristics were divided into five groups, corresponding to specific thresholds, and classified from least
developed to most advance. The categories of demographic transition were developed in the same way based on the criteria
of fertility and mortality. These categories with the selected thresholds are displayed in Table 1. A multivariate analysis is
presented at the end of the study, which is a linear regression on country characteristics, with an aim trying to explain differences
in incidence and case fatality between countries. Main results are presented in graphic form to better show patterns. Charts
showing incidence or case fatality are organized according to increasing economic development or demographic transition.
A priori, one could have expected a function parallel to the second bisector (more development corresponding to fewer cases
and fewer deaths), but in most cases, the diagram was reversed (more development associated with more cases), with a few
exceptions. Univariate relationships were confirmed by multivariate analysis, except those that were canceled out by the
correlations between variables and one variable which had an inverted relationship: The population age structure.

3. Results

3.1. Diffusion of the COVID-19

First cases of COVID-19 in Africa were notified to WHO in February 2020, by Egypt (February 15), Algeria (February
26), and Nigeria (February 28), practically at the same time as European countries, which were probably the main sources
of infection (Mehtar, Preiser, Lakhe, et al., 2020). Within 3 months, COVID-19 affected all African countries, the last
affected being Comoros (May 01) and Lesotho (May 13). Of the 56 African countries or territories reporting cases, 45
made their first report in March, and 6 in April. The spread of the virus was therefore very rapid, faster even than that of
the Spanish flu of 1918-1919 (Martini, Gazzaniga, Bragazzi, et al., 2019), and out of all proportion compared with other
emerging diseases such as HIV/AIDS which spread in the continent over several years (Buvé, Bishikwabo-Nsarhaza,
and Mutangadura, 2002), or Ebola which remained confined in a few countries (Kramer, Pulliam, Alexander, et al.,
2016). In fact, infectious diseases transmitted by the respiratory tract spread very quickly, and all the more quickly as the
communication routes are dense and travels are fast (planes, automobiles, coaches, public transport, etc.).

International Journal of Population Studies | 2020, Volume 6, Issue 2 3