CAPE TOWN, South Africa — About 12 million people in South Africa have "probably" been infected with the coronavirus, but that startlingly high number has not caused a similarly high death rate and might indicate a widespread "level of immunity," the country's health minister says.
More than 20% of South Africa's population of 58 million have had the virus at some point, Dr. Zweli Mkhize estimated this week. He cited studies that found the presence of coronavirus antibodies in blood samples taken from parts of the population. The findings have prompted the government to launch a national study, he said.
"South Africa has seen the surge receding, and thus raises the question of the level of immunity that may already be existing in society," he said.
Other studies have indicated that up to 40% of the population might be immune to the virus, Mkhize said. Some South African experts suggest that Africa's most developed economy may be approaching herd immunity, but scientists believe at least 70-80% of a population needs to be immune before there's any effect. And with COVID-19 it's unclear how long that immunity might last.
With confirmed virus cases dropping significantly, President Cyril Ramaphosa on Wednesday evening announced that South Africa's borders will reopen as of Oct. 1, with visitors required to show negative coronavirus test results no older than 72 hours before departure. Visitors will not be permitted from countries deemed at high risk, Ramaphosa said, not naming names.
Ramaphosa also announced further relaxed restrictions on public gatherings, to a maximum of 250 people indoors and 500 outdoors.
The president warned that the second wave of the pandemic in some countries has been worse than the first. "A second wave would be devastating to our country," he said.
South Africa's number of confirmed virus cases have dropped in recent weeks after a peak in late July that saw the country recording up to 15,000 cases daily, and raised fears that health services in some major cities might collapse. Official figures showed just 772 new cases on Tuesday.
South Africa is also seeing declines in hospital admissions, people in intensive care units and deaths attributed to COVID-19, health minister Mkhize said.
"Consistency across these indicators reassures us that, indeed, we are in the midst of a trough in the pandemic," he said.
South Africa has just over 650,000 confirmed cases of COVID-19, according to the government's latest official count, the eighth-highest caseload in the world. At its peak, South Africa was the fifth most affected country, behind the United States, India, Brazil and Russia, which all have much larger populations.
Experts have tried for months to figure out why South Africa's official death rate from COVID-19 is low — 15,641 people have died, according to government figures. There were fears at the start of the pandemic that poverty, crowded living conditions, restricted access to clean water and the high prevalence of tuberculosis and HIV would put South Africa, and Africa at large, in danger of millions of deaths.
So far, that hasn't happened. South Africa is by far the worst affected country in Africa with nearly half of the continent's 1.3 million confirmed cases. There have been 33,000 deaths from COVID-19 in the 54 countries in Africa, which has a population of 1.3 billion people. That death count is less than the number of people who have died in either the U.K. or Italy, and far less than the United States' 195,000 confirmed deaths.
But Africa's figures, tallied by the Africa Centers for Disease Control and Prevention, rely on figures from the individual countries and many have extremely limited testing.
The number of South Africa's actual deaths from COVID-19 is expected to be considerably higher. From early May until mid-September, the country has recorded 44,000 more deaths than the historic average. Many of those deaths are believed to be from COVID-19, but the people weren't tested. Other deaths could be people with other diseases who avoided care because of COVID-19 infection fears or couldn't access it because resources were diverted to the pandemic, experts have said.
"We think roughly 30,000 rather than 15,000 people have died from COVID-19," Shabir Madhi, professor of vaccinology at Johannesburg's University of the Witswatersrand, said in a webinar this week. "We must appreciate that there had been many deaths outside of hospitals."
Even with that higher level of deaths, South Africa's mortality rate from COVID-19 appears relatively low. Some health experts think that millions in South Africa's poor, densely populated townships — which many thought would be terribly affected by the virus — may have generated an immunity to the virus because of the previous and frequent spread of other coronaviruses, including those for the common cold and flu.
"They have been exposed, they developed this key cell immunity which helps them to fight the severe effects of COVID-19," said Madhi, the lead researcher on a clinical trial in South Africa of the coronavirus vaccine that Oxford University is developing with pharmaceutical company AstraZeneca. "They may have achieved an underpinning immunity."