Response to the article: Spread of COVID-19 cases in Africa

To the Editor,

I would like to take this opportunity to reply to some of the interesting comments made by González Rodríguez¹ on the article Why is the COVID-19 epidemic in Africa less “intense”?². First, I wrote the article a few months after the start of the COVID-19 pandemic, and did not therefore have the benefit of hindsight.

The article referred exclusively to Africa, and even now, one year on, the data continue to show that the epidemic is less intense in this continent than elsewhere. This is clearly illustrated by Fig. 1 of the article by González Rodríguez¹, where we can see that Africa is the second most populated continent, but the one with the lowest number of cases and deaths from COVID-19. Refining the geographical area even further, we can see from WHO country and global data³ and Worldometers data⁴ that tropical African countries are the least affected than other countries of this continent.

The minimum information needed to determine the impact of COVID-19 in a particular country is the number of cases and the mortality rate. I fully agree with González Rodríguez that COVID-19 cases are under-reported in Africa. This is due to poverty and scarcity of resources. It is true that testing was delayed in several African countries, but the main obstacle is that many patients do not go to the doctor and are not tested because they cannot afford to pay for the service. Interestingly, according to data from Worldometers⁴, by 19 April of last year, 946,894 tests/million inhabitants had been performed in Spain compared with only 1582 tests/million inhabitants in the Democratic Republic of the Congo (DRC). This phenomenon also occurs, to a lesser degree, on other continents. With regard to mortality, the criteria used to attribute deaths to COVID-19 are known to vary from country to country. Generally speaking, the death rate is underestimated. This distortion is sometimes due to political motives, and makes it impossible to accurately ascertain the real impact of the SARS-CoV-2 pandemic. A more accurate picture of the real impact can be obtained by studying the excess death rate^5,6. This parameter is measured as the difference between the reported number of deaths for a given period vs. the number of deaths that would be expected over that period in preceding years. Currently, it is reasonable to assume that excess deaths are mainly attributable to COVID-19, and though not exact, this calculation more closely reflects the real situation. In some countries, COVID-19-mortality rates are consistent with excess death rates, but in most the latter is higher. Spain is one of the countries in which the excess death rate exceeds the number of deaths attributed to COVID-19^5,6.

On the subject of the factors that can explain the low intensity of the pandemic in Africa, at least in the DRC, where I have lived for 2 years, I disagree with González Rodríguez’s suggestion this is due to the delayed arrival of the virus on the continent due to the early closure of borders and other social measures. This is because compliance with these measures, as shown by Wimba et al. in Bukavu⁷, a large city in eastern DRC, has been sketchy. This is also true of the capital, Kinshasa, which has a population equivalent to more than a quarter the entire population of Spain, and where people walk along the streets without masks, without observing social distancing, in continuous contact with each other in moto-taxis, taxis, crowded buses, and markets, and where confinement measures have hardly been implemented because it is impossible to comply with them. Furthermore, major deficits in health care due to lack of resources (for example, many countries have not yet begun their vaccination campaign), and the lack of sufficient beds and trained personnel to care for critically ill patients also contributes to extremely high mortality rates; however, only 745 deaths have occurred since the epidemic began⁴. In other words, despite the presence of social factors that would favour an exponential spread of the virus, this, paradoxically, has not occurred. Therefore, the lower intensity of the pandemic is really due to the presence of the other factors, although it is difficult to estimate the importance of each of these.

With regard to climate, available data on the influence of temperature, humidity and wind speed on the spread of the epidemic have a positive correlation with many African countries⁸. In fact, in European countries this same effect was observed in 2020 from May until August.

The important role of population pyramids in which a small proportion of the population is aged 65 years of age has also been established⁹; in my opinion, this may be the most important factor in the low mortality observed in these African countries.

There are few data regarding immunity and the role of genetics in COVID-19 resistance. However, there is evidence of a lower incidence of infection among people with the blood group O compared to the other groups. The most prevalent blood group in the DRC is, in fact, group O^10,11.

In my opinion, the higher death rates observed in Africa compared to Europe (see the author’s Fig. 2), despite the limitations of underreporting, is an interesting parameter that illustrates the quality of healthcare systems, as well as the evolution of their capacity to respond to the crisis. In the case of Africa, on 25 November 2020, the death rate was 2.39% and 2.64% on 19 April 2021⁴.

In conclusion, the COVID-19 pandemic in Africa, despite major limitations and shortcomings, continues to be less intense.