Africans may be twice
as likely to experience Covid-19 without any illness, compared with
people in the rest of the world, according to preliminary analysis by
the African branch of the World Health Organization.
The results from several blood-sample studies in
Africa could help to explain the low death rate that has confounded the
early predictions of devastation on the continent.
More than 80 per cent of Africans who were infected
with the virus were asymptomatic, the preliminary analysis found, based
on testing in several African countries. This compares with an estimated
40 per cent to 50 per cent who were asymptomatic in the rest of the
world.
“This is reinforced by
the fact that we have not seen health systems overwhelmed by very large
numbers of cases, and we’re also not seeing evidence of excess mortality
due to Covid-19,” said Matshidiso Moeti, the WHO regional director for
Africa, in a media briefing on Thursday.
Africa, with a population of 1.2 billion, has
recorded about 1.4 million cases and fewer than 35,000 deaths from the
virus – far lower, proportionally, than other regions of the world. The
United States, with slightly more than a quarter of Africa’s population,
has recorded 7.1 million cases and more than 206,000 deaths.
Some of the difference is explained by lower testing
rates in Africa, where only 1 per cent of the population has been
tested for the virus. But this fails to explain all of the difference.
“The missed Covid-19 cases are largely because they are asymptomatic,”
the WHO Africa branch said in a statement. “In addition, there is no
evidence of miscalculation of death figures, which are more difficult to
miss statistically.”
The case fatality rate in Africa has been 2.4 per
cent so far, significantly lower than the rate in most European and
North American countries.
Even when estimates include thousands of excess
deaths, likely to be caused by Covid-19 but not officially recorded as
such, the death rate in Africa has been lower than many experts had
expected. And the pandemic is now diminishing here: The number of new
African cases has been dropping for the past two months.
At the WHO briefing, experts cited several possible
factors to explain the lower rates of death and illness in Africa,
although they emphasized that more study is needed.
The most widely accepted factor is Africa’s youthful
population. Only about 3 per cent of Africans are over the age of 65,
the age group in which illness and death from the coronavirus are most
common. (By comparison, about 18 per cent of Canada’s population is over
the age of 65.)
More than 90 per cent of African coronavirus cases
have occurred among people under the age of 60, who are better able to
shrug off the virus. Death rates have been
higher in Algeria and South Africa where a larger percentage of the
population is over the age of 65, Dr. Moeti said.
Another factor could be Africa’s lower population
density and the fact that many people live in rural areas, spending more
time outdoors, analysts say. There is growing evidence that outdoor
spaces, because of their greater ventilation, tend to reduce exposure to
the virus, making it less dangerous.
“It doesn’t transmit very well outdoors, and Africa
has a significant population that is rural and spends a lot of time
outdoors,” Francisca Mutapi, professor of global health infection and
immunity at the University of Edinburgh, said at the Africa WHO
briefing.
Sam Agatre Okuonzi, a Ugandan health researcher and
hospital administrator, told the briefing that he agreed that Africa’s
risk of coronavirus infection may have been reduced by its larger rural
population.
A third factor was the imposition of early strict
lockdowns in many African countries, at a time when case numbers were
relatively small. This postponed the worst of the pandemic, allowing
hospitals and health workers to be better prepared with the latest
treatment methods.
A study this month by South Africa’s biggest medical
insurance company, Discovery Health, concluded that the lockdown in
South Africa will have averted 16,000 deaths by the end of the year. The
lockdown, now largely lifted, was one of the strictest in the world,
contributing to a sharp economic decline this year.
“Governments took early, quite drastic action
through the lockdowns, at great cost to their economies clearly, and
this has bought us some time,” Dr. Moeti said.
“It needs to be acknowledged because it made a
difference. And it made a difference at a high cost. They were tough,
courageous, very costly. We need to sustain this, so that the cost is
justified.”
A fourth factor, she said, was Africa’s relatively
poor road network and access to international flights, which slowed the
arrival of the virus and its transmission to rural areas.
“Africa is less internationally connected than other
regions,” Dr. Moeti said. “So we had some protection when the virus
first arrived.”
