Most adults infected with COVID-19 in South Africa are asymptomatic cases: official

“The majority of COVID-19 infections are going unnoticed,” said Dr Shabir Mahdi, who is heading the University of Oxford’s vaccine trials in South Africa.

In an interview with CNBC on Friday, Mahdi 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, Mahdi said.

He estimated that only about 10 per cent of all COVID-19 cases are being officially reported. Mahdi said around 80 per cent 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.

Madhi said the results on whether the vaccine works as 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 per cent 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,” he said.

“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,” he said.

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