Low Covid death rate in Africa is still a mystery to scientists

Since the beginning of the pandemic, the district’s Covid response center has recorded only 11 cases of the disease and no deaths. The regional hospital is full, but with malaria patients. The door of the isolated infirmary for Covid patients is locked and overgrown. People fill collective spaces for events such as weddings, concerts and football matches, and there are no masks in sight.

Sierra Leone, a country of 8 million on the coast of West Africa, looks like a land inexplicably spared from a plague. What happened or didn’t happen here and in much of sub-Saharan Africa is a great mystery of the pandemic.

The low rate of infections, hospitalizations and deaths from the coronavirus in West and Central Africa is the focus of a debate that divides scientists from the continent and the rest of the world.

Could it be that the sick and dead were simply not accounted for? If the coronavirus has in fact caused less devastation here, what is the reason? If it was equally virulent, how is it that we didn’t realize it?

In an interview in Sierra Leone’s capital, Freetown, Leone Health Minister Austin Demby said the responses “are relevant not only to us but also to the greater public good”.

The assertion that Covid is not such a big danger in Africa has sparked a discussion about whether or not the African Union’s campaign to vaccinate 70% of Africans against the virus this year is the best use of health funds. , given that the devastation caused by other pathogens, such as malaria, appears to be much greater.

In the first months of the pandemic, there were fears that Covid could eviscerate Africa, running rampant through countries with health systems as weak as Sierra Leone, which, according to the World Health Organization (WHO), has only three doctors for each 100 thousand inhabitants. The high prevalence of malaria, HIV, tuberculosis and malnutrition was seen as a trigger for the disaster.

This did not happened. The first version of the coronavirus that toured the world had comparatively minimal impact in this region. The beta variant wreaked havoc in South Africa, as did delta and omicron, but much of the rest of the continent did not report comparable deaths.

Now, in the third year of the pandemic, new research reveals that there is no longer any doubt as to whether Covid has spread widely in Africa: it has.

Studies that tested blood samples to check for the presence of antibodies to Sars-CoV-2, the official name for the virus responsible for Covid, point out that about two-thirds of the population in most sub-Saharan countries have these antibodies. As only 14% of the population has received any type of anti-Covid vaccine, antibodies are mainly the result of infections.

A new WHO-led but not yet peer-reviewed analysis summarized research across the continent and found that by the third quarter of 2021, 65% of Africans had been infected — a higher incidence than many other parts of the world. Only 4% of Africans had been vaccinated when these data were collected.

Therefore, the virus is present in Africa. Is it killing fewer people?

Some speculation focused on the relative youth of Africans. The average age of Africans is 19, while in Europe it is 43 and in the United States 38. Almost two-thirds of people in sub-Saharan Africa are under 25, and only 3% are 65 or older.

This means that comparatively far fewer people have lived long enough to develop the health problems (cardiovascular disease, diabetes, chronic respiratory disease and cancer) that could greatly increase the risk of serious illness and death from Covid. Young people infected with the coronavirus are often asymptomatic, a fact that may be responsible for the low number of reported cases.

Several other hypotheses have been put forward. Hot weather and the fact that people spend most of their lives outdoors can make it difficult for the disease to spread. Or this may be due to low population density in many areas, or limited public transport infrastructure.

Perhaps exposure to other pathogens, including other coronaviruses and lethal infections like Lassa fever or Ebola, somehow provided people with protection.

But since Covid spread rapidly across South and Southeast Asia last year, these theories have become more difficult to accept. After all, India’s population is also young (average age of 28), and the climate in the country is also relatively warm.

But researchers found that the delta variant caused millions of deaths in India, far more than the 400,000 officially reported deaths. And rates of infection with malaria and other types of coronavirus are high in countries, including India, which are also experiencing high death rates from Covid.

Are Covid deaths in Africa just not being counted?

Most global Covid case tracking tools do not record any cases of the disease in Sierra Leone, because testing for the virus is virtually non-existent in the country. Without tests, there are no cases to report.

A research project at Njala University in Sierra Leone concluded that 78% of people have antibodies to this coronavirus. But Sierra Leone has only had 125 Covid deaths reported since the start of the pandemic.

Most people die at home, not in a hospital, either because they don’t have access to a hospital or clinic or because their families take them home to die. Many deaths go unreported to civil authorities.

This pattern is common across sub-Saharan Africa. Recent research by the United Nations Economic Commission for Africa found that official registration systems capture just one in three deaths.

The only sub-Saharan country where virtually all deaths are recorded is South Africa. And the data makes it clear that Covid caused many deaths in this country, much more than the reported deaths.

Excess mortality data reveals that between May 2020 and September 2021, 250,000 more people died from natural causes than predicted for that period, based on the pattern of previous years. The phases of increase in the death rate correspond to the increase in Covid cases, suggesting that the virus was the culprit.

Dr. Lawrence Mwananyanda, an epidemiologist at Boston University and special adviser to the president of Zambia, said he had no doubt that the impact of Covid in Zambia was as strong as in South Africa, but that Zambian deaths were not captured by a registration system. much weaker. Country with more than 18 million inhabitants, Zambia has only 4,000 reported cases of death from Covid.

“If this is happening in South Africa, why would it be any different here?” said the epidemiologist. In reality, he added, South Africa has a much stronger health system, which should point to a lower, not a higher, death rate.

A team of researchers that Mwananyanda led found that during the delta wave in Zambia, 87% of dead bodies in hospital morgues were infected with Covid. “The morgues were full. Nothing else was different. The only difference is that we Zambians have very incomplete data.”

The weekly The Economist, which has been tracking excess deaths throughout the pandemic, points to similar death rates across Africa. Sondre Solstad, responsible for the Africa model, said there were between 1 million and 2.9 million excess deaths on the continent during the pandemic.

“It would be beautiful if Africans were spared the coronavirus, but they are not,” he said.

But many scientists tracking the pandemic in the field disagree. It is said that it is not possible that hundreds of thousands or even millions of deaths from Covid have gone unnoticed.

“We haven’t seen mass burials in Africa. If that had happened, we would have noticed,” said Dr. Thierno Baldé, director of the WHO emergency response program for Covid in Africa.

The Doctor. Salim Abdool Karim, who is part of the African CDC’s Covid task force and was part of the team of researchers that accounted for surplus deaths in South Africa, believes that the total number of deaths in the entire continent is likely to be consistent with that of your country.

For him, there is simply no reason why Gambians or Ethiopians are less vulnerable to Covid than South Africans.

But he also stressed that it is clear that there are not large numbers of people coming to hospitals suffering from acute respiratory distress.

For him, the youth of the population is clearly a crucial factor, and at the same time, some older people who die from strokes or other Covid-induced causes are not being identified as having died from Covid. Many do not even make it to hospitals, and their death is not recorded.

But others are not getting sick in proportions similar to those seen in other countries and regions, and this is a mystery that needs to be solved.

“It’s tremendously important for things as basic as vaccine and treatment development,” explained Dr. Prabhat Jha, director of the Center for Research in Global Health, Toronto, who is leading a study to analyze causes of death in Sierra Leone.

Researchers working with Jha have been using innovative methods (such as looking for any revenue increases that city radio stations in Sierra Leone may have had in the past two years from publishing obituaries) to try to see whether deaths may have increased without for this to be noticed, but he said it is clear that there has been no great tide of extremely sick people.

Some organizations working on the Covid vaccination campaign say the effort should be reviewed in light of lower rates of illness and deaths. John Johnson, vaccination adviser to Doctors Without Borders, said vaccinating 70% of Africans made sense a year ago, when it looked like vaccines could guarantee long-term immunity and make it possible to end Covid transmission.

But now that protection against the virus is known to weaken over time, herd immunity no longer seems like a viable goal. Thus, in places like Sierra Leone, an immunization strategy that focuses only on the most vulnerable sectors of the population would make better use of available resources.

“Is vaccinating the population against Covid the most important thing in countries where there are much bigger problems with malaria, polio, measles, cholera, meningitis, malnutrition?” he asked.

“Is that what we want to spend our resources on in these countries? Because at this point, vaccination is not about helping these people: it’s about trying to prevent the emergence of new variants.”

And, he said, the new variants of Covid pose a greater danger in countries with older populations and with high levels of comorbidities such as obesity.

Other experts caution that the virus is still an unpredictable adversary and that restricting efforts to vaccinate the population of sub-Saharan Africa could still result in tragedy.

“We cannot get complacent and assume that Africa cannot go India’s way,” said Jha.

It is still possible that a new variant as infectious as the omicron but more lethal than the delta could emerge, he warned, leaving Africans vulnerable unless vaccination rates increase significantly.

“We should really avoid the arrogant idea that Africa is safe,” he said.

^{Translation by Clara Allain}