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Africa's low COVID-19 death toll

 Africa's Surprisingly Low COVID-19 Death Toll 

    Although Africa makes up 17% of the world's population, by July 2020, the continent only accounted for 3% of global COVID-19 cases and 5% of reported deaths. Researchers have attributed the disparity of cases and deaths in Africa to limited testing/diagnosis, stricter containment measures, a high population of young people, and higher asymptomatic or mild cases of COVID-19. However, the spread of the coronavirus in Africa has been poorly described and limited data has been produced to backup the disparity hypothesis. To better understand the low number of COVID-19 cases and deaths in Africa, a group of researchers collected and tested blood samples from thousands of Kenyan residents. Their results, which revealed interesting conclusions pointing to higher infection rates than reported, were published in the journal Science in November 2020.

Background

    Kenya's first case of COVID-19 was detected on March 12, 2020. By July 31, there were a recorded 20,636 cases and 341 deaths due to COVID-19. The increase in cases was significantly lower than that in Wuhan, Europe, and the United States. To better understand why this may be the case, researchers collected a total of 3,174 blood samples from 4 regional blood transfusion centers in Kenya (Mombasa, Nairobi, Kismu, and Eldoret) between April 30 and June 16, 2020. The samples were collected from individuals aged 15-66 years and used to conduct a seroprevalence survey.

    Seroprevalence surveys use blood samples to identify individuals in a population who have antibodies against a virus. In this study, blood samples were tested for the anti-SARS-CoV-2 IgG antibody. If an individual tests positive for the IgG antibody, this means that they were previously infected with the coronavirus and as a result, developed antibodies to fight off a second infection.  (See Antibody Responses in Children vs. Adults for more information)   

Study Results and Implications

    The study results indicate that the population-weighted and test-adjusted seroprevalence for Kenya was 4.3%. In other words, 4.3% of Kenyans developed IgG antibodies against the coronavirus. Seroprevalence was also found to be higher in younger age groups, peaking in 35-44 year olds and declining in those aged 45 or older.  However, seroprevalence was similar for both sexes. The 3 largest urban counties, Mombasa, Nairobi, and Kismu had the highest COVID-19 seroprevalence of 8%, 7.3% and 5.5%. 

    Kenya's seroprevalence rate of 4.3% was much higher than what researchers expected. With Kenya's population of 53 million people, a 4.3% seroprevalence would mean that 1.3 million individuals had a previous infection of COVID-19 and developed the antibodies against the virus. Yet, only 20,636 COVID-19 cases were reported at the time of the study. The significant inconsistency between these numbers suggests that many individuals were unaware they were once infected with the coronavirus, and/or there was an oversight in recording a majority of COVID-19 cases in the country's healthcare database. Furthermore, although Spain's seroprevalence and population size are very similar to that of Kenya's, Spain had over 70x more deaths (about 28,000) than Kenya's 341 deaths. Although Africa's low death toll still remains largely a mystery, scientists have formed speculations as to why that may be the case. Authors from the study cited Africa's younger population as one of the explanations behind Kenya's low death rate. The possibility of Kenyans having an "innate immunity to the disease" was also mentioned as another prospect by Dileep Mavalankar, director of the Indian Institute of Public Health. The study's researchers believe these results suggest that the effects of the coronavirus have been 'attenuated' or weakened in Africa. 


Sources

1. Uyoga, Sophie, et al. “Seroprevalence of Anti–SARS-CoV-2 IgG Antibodies in Kenyan Blood Donors.” Science, American Association for the Advancement of Science, 11 Nov. 2020, science.sciencemag.org/content/early/2020/12/01/science.abe1916. 

2. Shetty, Disha. “Kenyan Study Suggests Parts Of Africa Saw Fewer Severe Cases Of Covid-19 Despite Wide Spread.” Forbes, Forbes Magazine, 24 Nov. 2020, www.forbes.com/sites/dishashetty/2020/11/24/kenyan-study-supports-impression-that-covid-19-spread-weaker-in-africa/?sh=2f24dafe142b. 

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