Hong Kong finds first documented case of COVID-19 reinfection

A man who had recovered from the virus was infected again four-and-a-half months later.

The University of Hong Kong's findings indicate the disease, which has killed more than 800,000 people worldwide, may continue to spread amongst the global population despite herd immunity, they said.

The 33-year-old male was cleared of COVID-19 and discharged from a hospital in April, but tested positive again after returning from Spain via Britain on Aug. 15.

The patient had appeared to be previously healthy, researchers said in the paper, which was accepted by the international medical journal Clinical Infectious Diseases.

He was found to have contracted a different coronavirus strain from the one he had previously contracted and remained asymptomatic for the second infection.

"The finding does not mean taking vaccines will be useless," Dr. Kai-Wang To, one of the leading authors of the paper, told Reuters. "Immunity induced by vaccination can be different from those induced by natural infection," To said. " will need to wait for the results of the vaccine trials to see if how effective vaccines are."

World Health Organization (WHO) epidemiologist Maria Van Kerkhove said on Monday that there was no need to jump to any conclusions in response to the Hong Kong case.

Instances of people discharged from hospitals and testing positive again for COVID-19 infection have been reported in mainland China. However, in those cases, it was not clear whether they had contracted the virus again after full recovery - as happened to the Hong Kong patient - or still had the virus in their body from the initial infection.