Why low COVID-19 death rates in Africa

More effective response

An important possibility is that the public health response of African countries, prepared by previous experiences (such as outbreaks or epidemics) was simply more effective in limiting transmission than in other parts of the world.

However, in Kenya it’s estimated that the epidemic actually peaked in July with around 40% of the population in urban areas having been infected. A similar picture is emerging in other countries. According to a report published in August in the journal `Science’ titled “Africa’s pandemic puzzle: why so few cases and deaths?”, after testing more than 3000 blood donors, immunologist Sophie Uyoga of the Kenya Medical Research Institute–Wellcome Trust Research Programme and colleagues estimated that one in 20 Kenyans aged 15 to 64—or 1.6 million people—has antibodies to SARS-CoV-2, an indication of past infection.

That would put Kenya on a par with Spain in mid-May, when that country had 27,000 official COVID-19 deaths. Kenya’s official toll stood at 100 when the study ended. And Kenya’s hospitals are not reporting huge numbers of people with COVID-19 symptoms.

Other antibody studies have yielded similarly surprising findings. From a survey of 500 asymptomatic health care workers in Blantyre, Malawi, immunologist Kondwani Jambo of the Malawi–Liverpool Wellcome Trust Clinical Research Programme and colleagues concluded that up to 12.3% of them had been exposed to the coronavirus. Based on those findings and mortality ratios for COVID-19 elsewhere, they estimated that reported number of deaths in Blantyre at the time, 17, was eight times lower than expected.

Scientists who surveyed about 10,000 people in two cities in Mozambique, Nampula and Pemba, found antibodies to SARS-CoV-2 in 3% to 10% of participants, depending on their occupation; market vendors had the highest rates, followed by health workers. Yet in Nampula, a city of approximately 750,000, a mere 300 infections had been confirmed at the time. Mozambique only has 16 confirmed COVID-19 deaths. Yap Boum of Epicentre Africa, the research and training arm of Doctors Without Borders, says many people in Cameroon have COVID-19 antibodies as well.

This implies that measures put in place had little effect on viral transmission per se, though it does raise the possibility that herd immunity is now playing a role in limiting further transmission.

At the same time there is another important possibility: the idea that viral load (the number of virus particles transmitted to a person) is a key determinant of severity. It has been suggested that masks reduce viral load and that their widespread wearing may limit the chances of developing severe disease. While WHO recommends mask wearing, uptake has been variable and has been lower in many European countries, compared with many parts of Africa.

So is Africa in the clear? Well, obviously not. There is still plenty of virus around and we do not know what may happen as the interaction between the virus and humans evolves.

However, one thing that does seem clear is that the secondary effects of the pandemic will be Africa’s real COVID-19 challenge. These stem from the severe interruptions of social and economic activities as well as the potentially devastating effects of reduced delivery of services which protect millions of people, including routine vaccination as well as malaria, TB and HIV control programmes.

Research agendas

Major implications of the emerging picture include the need to re-evaluate African COVID-19 research agendas. While many of the priorities originally identified may still hold, their relative importance is likely to have changed. The key point is to deal with the problems as they are now rather than as they were imagined to be six months ago.

The same thing applies for public health policy. Of course, basic measures such as hand washing remain essential (regardless of COVID-19) and wearing masks should be continued while there is any level of COVID-19 transmission. However, other measures with broader effects on society, especially restrictions on educational and economic activity, should be under continuous review.

A key point now is to increase surveillance and ensure that flexible responses are driven by high quality real time data.

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Kevin Marsh is Professor of Tropical Medicine, University of Oxford and Moses Alobo is Programme Manager for Grand Challenges Africa, African Academy of Sciences.

Source:theconversation