JOHANNESBURG—Earlier this year, doctors and epidemiologists in South Africa’s economic capital were bracing for the worst. A new coronavirus strain was surging across the country, thousands of holidaymakers were due to return from Covid-19 hot spots, and one in three coronavirus tests was coming back positive.
Then something unexpected happened: Covid-19 cases started dropping.
Since mid-January, confirmed Covid-19 infections in South Africa have fallen from a record of nearly 22,000 a day to around 1,000, without a large-scale vaccination campaign or stringent lockdown. Fewer than 5% of Covid-19 tests are finding traces of the virus, a sign that health agencies are missing fewer cases. The government has lifted most of its remaining virus restrictions for the country of 60 million people.
The cause of this steep decline in cases remains somewhat of a mystery. As in other countries that have at some point experienced surprising drops in Covid-19 cases—such as India, Pakistan and some parts of Brazil—epidemiologists and virologists are piecing together different explanations for why the outbreak in South Africa isn’t following patterns set elsewhere.
Those range from important population groups reaching sufficient levels of immunity to slow down transmission, to people sticking more closely to social-distancing rules, such as wearing masks and voluntarily reducing contacts, when deaths were mounting before the decline.