A meta-analysis, a synthesis of 151 studies on seroprevalence in Africa between January 2020 and December 2021 and now uploaded to a preprint server while under peer review suggests up to 65% of Africans, continent-wide, have already been infected with SARS-CoV-2, the virus behind COVID-19. If the math is correct there were 97 times more infections in Africa than reported confirmed cases.  Despite acknowledged widespread natural immunity in Africa WHO pushes aggressively to vaccinate more of the population, to date only about 16% of the population on the continent is vaccinated against COVID-19.

Why Seroprevalence Studies?

Seroprevalence studies provide data on asymptomatic or under-reported infections that may have been missed by routine diagnostic testing, which in Africa has focused on travelers and people who came to hospitals with COVID-19 symptoms. While this new analysis provides insight into the evolution of the pandemic, routine testing remains a critical component of the COVID-19 pandemic in all countries.

Africa during the Pandemic

The WHO writes that by 6 April 2022, there were 11.5 million confirmed cases and more than 252 000 deaths reported on the continent. It is likely that numbers of actual exposure to the virus have increased even more since September 2021.”

WHO argues that the people of Africa have had milder COVID-19 cases compared with people in other parts of the world because there is a comparatively smaller proportion of people with risk factors such as diabetes, hypertension, and other chronic diseases that are associated with more severe cases and deaths?  Africa’s youthful population is also a protective factor. 

Other factors have been proposed, such as the frequent use of ivermectin in many of the countries in the continent as part of antiparasitic regimen.  This claim hasn’t been proven.

Delivering the Findings

During a press conference recently, Dr. Matshidiso Moeti, WHO Regional Director for Africa spoke along with the study’s Coordinating Lad Author, Professor Guéladio Cissé, Intergovernmental Panel on Climate Change, Swiss Tropical and Public Health Institute, University of Basel, Switzerland, and Dr. Irene Owusu Donkor, Postdoctoral fellow, African Postdoctoral Training Initiative and Research fellow, Noguchi Memorial Institute for Medical Research, Ghana. The study authors were part of the UNITY Studies Collaborator Group.

The Findings

This study, still not peer-reviewed hence shouldn’t be used for any conclusions as of yet reveals that exposure to SARS-CoV-2 skyrocketed from 3% (1.0-9.2% range) in June of 2020 to 65% (56.3-73% range) by September of 2021, or 800 million infections compared with 8.2 million cases reported at that time. The study showed that exposure to the virus rose sharply following the emergence of the Beta and the Delta variants.  

The analysis revealed that the true number of infections could be as much as 97 times higher than the number of confirmed reported cases. This compares to the global average where true number of infections is 16 times higher than the number of confirmed reported cases.

As reported in the WHO press release, seroprevalence varied widely within and across countries in Africa – higher in more dense urban areas than in less populated rural areas – and between age groups, with children aged 0-9 years having fewer infections compared with adults. Exposure to the virus also varied between countries and Africa’s sub-regions: seroprevalence appears to be highest in Eastern, Western, and Central African regions. 

Broad-based Pop Health Implications—Herd Immunity?

The new analysis suggests that more than two-thirds of all Africans have been exposed to the COVID-19 virus. Globally seroprevalence studies have found a significant under-counting of cases occurring across the globe with 45.2% of the world’s population estimated to have been infected with the virus by September 2021. It is, however, difficult to compare figures for Africa with those of other regions, as many of the studies conducted cover different time periods.

The continent differentiates itself from other regions by its a high number of asymptomatic cases, with 67% of cases having no symptoms.

“This analysis shows that current reported COVID-19 confirmed cases are only a fraction of the actual number of infections on the continent,” said Dr. Moeti, who continued “This under-counting is occurring worldwide and it’s no surprise that the numbers are particularly large in Africa where there are so many cases with no symptoms.”

Push for Vaccination

While this study reveals a substantial percentage of the population has already been infected with SARS-CoV-2 and thus has some levels of natural immunity and the WHO acknowledges that generally, the African population (young, fewer comorbidities, etc.) are less likely to experience severe disease nonetheless none of those factors were considered as part of a publicly shared COVID-19 risk-benefit analysis.

In fact, declaring that the virus is actually pervasive, circulating around the population, often in the form of new highly transmissible variants the WHO argues vaccines are more important than ever for the African population declaring “The seroprevalence analysis shows just how much the virus continues to circulate, particularly with new highly transmissible variants. The risks of more lethal variants emerging which overwhelm immunity gained from past infections cannot be brushed aside. Vaccination remains a key weapon in the fight against COVID-19.”

They base this rationale on “multiple studies” revealing that vaccination is beneficial for individuals who have already been infected. To date, about 209 million people representing 16% of the population have been vaccinated.   WHO continues to support countries’ ramp-up vaccination?

Call to Action: Follow the link to the study at medRxiv

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