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.
[E]pidemiologists 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.
The simplest explanation for the sudden mid-January drop in cases is that sections of the population had reached a level of immunity that made it harder for the virus to jump between different groups, said Jinal Bhiman, a principal medical scientist at the NICD.
Only about 1.5 million South Africans, around 2.5% of the population, have tested positive for Covid-19. But it is clear that the actual level of infection has been much higher.