IT is impossible to contract coronavirus twice, according to the South Korean centre for disease control and prevention (CDC).

Researchers there concluded that reported cases of people relapsing were the result of testing faults.

A total of 245 people have died in South Korea after being diagnosed with Covid-19, out of 10,000 confirmed cases – a mortality rate of just 2.3%.

Around 280 patients were thought to have become infected for a second time, sparking fears that the virus was mutating too quickly for people to get the chance to develop immunity.

But CDC scientists found there was no evidence of changes in Covid-19 which would be sufficient to disguise it from the human immune system.

In the cases of those who were diagnosed for a second time, the researchers reported false positives produced by the polymerase chain reaction (PCR) test, which checks for particles of the virus in the blood.

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The CDC also found that Covid-19 does enter a person’s cell nucleus. "This means it does not cause chronic infection or recurrence," explained Dr Oh Myoung-don, the head of the CDC committee.

However, the possibility of the coronavirus potentially mutating in the future and re-infecting people, as flu does, was not ruled out.

The new finding could impact the World Health Organisation’s guidance on so-called "immunity passports".

Previously, WHO had warned against allowing those who have antibodies for the virus to return to work, stating there was "no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection".