University of Hong Kong microbiologist Yuen Kwok-yung said on Tuesday that a 33-year-old man who recovered from Covid-19 – only to test positive for the coronavirus again four months later – was most likely re-infected during a trip to Spain.
Yuen, a member of the government’s expert advisory group on Covid-19, said the man has quite a high viral load.
He said the case is different to other patients who have recovered, but remnants of the virus in their system meant they tested positive for Covid-19 again.
Yuen also said it was possible that the man’s immune response couldn’t protect him against a mutated virus, or that his antibodies only lasted a short time because of issues with his immune system.
Leung Chi-chiu from the Medical Association said this case may shed light on the development of vaccines.
He said the protection offered by vaccines may not be long-lasting, so people may need to be re-vaccinated.
“But as of this moment, we need to establish whether this is a true re-infection. Whether there is any significant change and mutation in the second viral strain, so as to evade the immunity caused by the first infection,” said Leung.