By The Conversation

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There’s been an increase in COVID-19 deaths across Africa since mid-July 2021. But the impact of the pandemic in sub-Saharan Africa remains markedly lower compared to the Americas, Europe and Asia.

The reasons for this are not yet clear. Several factors have been suggested as potentially influencing the low burden of Covid-19 illness. These include age demographics, lack of long-term care facilities, potential cross-protection from previous exposure to circulating coronaviruses, limitations of SARS-CoV-2 testing which may have resulted in an undercounting of deaths, and effective government public health responses. In a recent paper our team of public health researchers, led by health analyst Janica Adams, examined these possible explanations by reviewing the scientific literature.

The aim was to help guide public health decision making to contain Covid-19. A number of hypotheses emerged from the literature review.

In this article we explore the most common ones. More research is needed to better understand how these factors contribute to the lower burden of Covid-19 disease in the African context.

Age has been observed as a significant risk factor for severe Covid-19 illness. Most deaths occur in those aged 65 or older. The median age in North and South America, Europe and Asia ranges from 32 to 42.5 years.

The age demographic structure of sub-Saharan Africa is much younger the median age is 18. The stark difference in age demographics can be demonstrated by comparing Canada and Uganda, which are similar in population size.

In Canada, the median age is 41.1. Around 18% of the population is 65 or older. In contrast, the median age of Uganda is 16.7. Only 2% of the population is 65 or older. Canada has recorded nearly 1.5 million Covid-19 cases and 27,000 deaths compared to fewer than 100,000 cases and 3,000 deaths in Uganda.

Covid-19 has a significant impact on older people. Countries with larger proportions of older people are more likely to be hardest hit.

Most elderly people in sub-Saharan Africa don’t live in long-term care facilities. These facilities pose significant risks for infectious diseases. Covid-19 has substantially affected those living in long-term care facilities.

During the first wave of the pandemic, about 81 percent of deaths in Canada occurred in those facilities.

In sub-Saharan Africa, provision of care is mostly left to families. This limits the number of formal caregivers and thus reduces the chance of transmission. An exception to this is South Africa, which has an established long-term care sector.

South Africa was the worst affected country in sub-Saharan Africa. And 33 percent of Covid-19 outbreaks in South Africa occurred in longterm care facilities during the first wave.

Potential cross-protection from local circulating coronaviruses It’s been suggested that prior exposure to circulating coronaviruses could reduce the severity of Covid-19 illness if people have developed antibodies.

A previous study demonstrated that prior exposure to endemic coronaviruses resulted in lower chance of death and lower disease severity compared to those who were not previously exposed.

Human-bat interactions are common in some rural areas of Africa. Limitations of SARS-CoV-2 testing There are concerns that the limited SARSCoV-2 testing may have resulted in an undercounting of Covid-19-related deaths in sub-Saharan Africa. Insufficient data collection may mean we don’t really know the incidence and prevalence of Covid-19.

Though varying across sub-Saharan Africa, testing levels have been low compared to other areas of the world.