Particularités de la 3e vague de la pandémie à COVID-19 en Afrique sub-Saharienne, cas de la République Démocratique du Congo comme exemple

During an epidemic, a wave is defined as one or more peaks in the number of infections. It can also refer to the repetition of epidemic cycles. According to many experts, repetitive waves are the norm in the epidemiology of viral infections; only the development of effective vaccines or curative drugs can ultimately break these cycles. Since the first cases reported in Wuhan in China, in December 2019, the pandemic of infection of “SARS-CoV-2 namely the "coronavirus disease 2019" (COVID-19) has already experienced 3 waves having affected all continents. Some countries, especially in Europe, even fear entering the fourth wave. In sub-Saharan Africa (SSA), after a first wave (March, April, May and June 2020) and a second wave (November, December 2020 and January 2021), the World Health Organization (WHO) has again sounded the alert in May 2021 following the upsurge in the number of COVID-19 cases in SSA. In DR Congo, it was on June 3, 2021 that the government officially announced the country's entry into the third wave with the city of Kinshasa as the epicenter of the pandemic. In the first two waves, several observers called the situation in SSA countries a paradox. Considering the denial of the disease and the non-respect of barrier gestures by a large part of the population, the weakness of the health systems, the absence of equipped intensive care unit, the limited number of qualified medical staff and the absence of oxygen production units, we were convinced that the SSA would experience a disaster. However, the poorest continent on the planet was also the least affected both in numbers of cases of infections and in number of deaths. Among the few countries that had been exceptions were Nigeria and South Africa, the two largest economic powers of the continent. Among the hypotheses that could explain this relative protection of SSA, we mention the youth of its population, the limited number of international flights, the relatively favourable climatic environment and probably the cross-immunity. The role of genetic factors has so far not been proven. Long before the outbreak of the third wave of COVID-19 in DR Congo, the news cycles were dominated by the launches of massive vaccination campaigns around the world. This step was described as historic, especially since it is practically the largest vaccine purchase and supply operation in human history. The "COVID-19 Vaccines Global Access" (Covax) initiative had the objective of ensuring an equitable distribution of vaccines against COVID-19 throughout the world, and the DR Congo had opted for the use of the AZD1222 vaccine (Astra Zeneca = Vaxzevria), which meets the storage conditions existing in the country (between 2 and 8 degrees Celsius). Very early, this vaccination program was compromised. Because of the controversies around the possible side effects of the vaccine (thrombosis in particular), 1,300,000 doses of vaccines had been redistributed to other countries. Of the remaining 400,000 doses, a part of the vaccine was destroyed for reasons of non-use before the expiry date. To date, all of the country's 26 provinces are affected by COVID-19 and the vaccination campaign has been temporarily suspended. The third wave of COVID-19 was favoured by several combined factors such as the non-closure of national borders and international airports, denial of the disease, inefficient use of public health measures, vaccination failure, etc. This wave is largely linked to the Delta variant of SARS-CoV2 already detected in 124 countries including the DR Congo. The R0 level (average number of patients that a contagious person can infect) of the historical SARS-CoV-2 virus is estimated at 3, that of the Alpha variant at around 4.5 and that of the Delta variant at around 6.6 (in the absence of barrier measures including vaccination). The virulence and immune escape potential of this variant are currently the subject of many studies, sometimes contradictory. Most of them show reduced efficacy of vaccines against this variant. Others report that having previously contracted COVID-19 would not be a guarantee against reinfection with this variant. In fact, antibodies produced during a first infection with the Alpha variant would confer good protection against all the variants, but those developed following an infection with the Beta or Gamma variants seemed less effective in the event of exposure to the Delta variant. Compared to the two previous waves, the third has particular kinetics: the circulation of the virus accelerated during May 2021 in Kinshasa, with a larger number of people hospitalized in June than the previous peaks. Around mid-July 2021, the number of cases began to decline as some provinces in the country, especially those in the East, experience an outbreak of cases. While men are still more affected than women, the frequency of young patients seems to be increasing. As in two previous waves, we do not observe high mortality as in other continents where the Delta variant circulates. The official statistics of cumulative deaths published by the national technical secretariat for the response against COVID-19 indicate a lethality of 2.1 %. This has been declining continuously since the first wave. Better preparation of healthcare teams, earlier referral of patients and improvement of equipment in hospital partly explain these results, even if documented cases of community deaths without systematic screening for COVID-19 can bias the statistics. Even if the SSA always seems to be more resistant to COVID-19, we have to be careful in the face of this new virus. Experience of the last two years having shown that few vaccinated people have presented severe forms of COVID-19, so it should be recognized that to date, the best way to achieve collective immunity of the population remains vaccination. "Sometimes the germ mutates and becomes more dangerous during an epidemic wave; however, the more the pathogen kills humans, the less it spreads", said Laurent-Henri Vignaud (science historian at the University of Bourgogne, France). Source : Cellule d’analyse, Secretariat technique de la riposte contre la Covid-19, Ministere de la sante, RD Congo Source : Cellule d’analyse, Secretariat technique de la riposte contre la Covid-19, Ministere de la sante, RD Congo Conflict of interest The author declared no competing interest References Renuka Raman, Krishna J. Patel, Kishu Ranjan. COVID-19: Unmasking Emerging SARS-CoV-2 Variants, Vaccines and Therapeutic Strategies. Biomolecules 2021; 11(7): 993. DOI: 10.3390/biom11070993. Zeyaullah M, AlShahrani AM, Muzammil K, Ahmad I, Alam S, Khan WH, Razi Ahmad. COVID-19 and SARS-CoV-2 Variants: Current Challenges and Health Concern. Front Genet. 2021; 12: 693916. doi: 10.3389/fgene.2021.693916.