Over half of Covid-19 infected adults in South Africa are asymptomatic: Official

A top health official in South Africa has said that about 50 to 66 percent of all the adults infected with the Covid-19 disease in the country are asymptomatic, with many infections going undetected.

The coronavirus, which first emerged in China's Wuhan city, has claimed 3,860 lives in South Africa with over 2,50,000 confirmed cases.

“The majority of Covid-19 infections are going unnoticed,” according to Dr Shabir Madhi, the leader of the South African leg of an international vaccine trial headed by the University of Oxford.

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In an interview with CNBC on Friday, Madhi said the high number of asymptomatic cases was causing difficulties in vaccine trials.

The enrolment process has shown that far more people are asymptomatic than what was previously believed, he said.

He estimated that only about 10 percent of all Covid-19 cases are being officially reported.

Madhi said around 80 percent of all children who are infected are asymptomatic.

The clinical trials require people who have not been infected by the virus. Part of the enrolment process for the Covid-19 vaccine trial involves the screening of individuals.

Qualifying participants are randomly allocated into one of two groups -- vaccine group or placebo group.

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Madhi said the results on whether the vaccine works as a protection against Covid-19 would be available by the end of November this year, but the trials may be extended into the second quarter of next year.

He warned against 'undue' optimism, reminding that only 10 percent of vaccines that go into clinical trials are eventually licensed for use.

“Right now there are approximately 200 vaccines that are being developed (around the world) for Covid-19.

“It would be a huge accomplishment if, over the next 12 to 18 months, we are successful in showing that even one out of every 20 of the vaccines that go into human studies are safe and provide some protection against Covid-19,” Madhi said.

He said that for the next year at least, the only reliable protection against the Covid-19 would be the non-pharmaceutical interventions of handwashing, sanitisation, and social distancing.