A 33-year-old man from Hong Kong became the first documented case of Covid-19 reinfection in the world, according to researchers at the University of Hong Kong, state media reported.
The patient was discharged after being cured of the virus in April but earlier this month tested positive again after returning from Spain, state broadcaster RTHK said.
According to the city’s health authorities, it was initially thought that man could be a “persistent carrier” of SARS-CoV-2 – the coronavirus behind the Covid-19 pandemic – and was carrying the virus inside his body since his previous condition.
However, researchers at the University of Hong Kong found that the genetic sequences of the virus strains that the man contracted in April and August were clearly different.
This discovery poses a setback for those formulating their pandemic strategy on the supposed immunity gained after overcoming the disease.
“Many believe that recovered Covid-19 patients have immunity against re-infection because most developed a serum neutralizing antibody response,” said the study by the Hong Kong university.
However, the researchers underlined that “there is evidence that some patients have waning antibody level after a few months.”
The study has been accepted by the medical journal ‘Clinical Infectious Diseases’, published by the Oxford University in England.
“Our findings suggest that the SARS-CoV-2 may persist in the global human population as is the case for other common cold-associated human coronaviruses, even if patients have acquired immunity via natural infection,” said the experts from the University of Hong Kong.
Hence, they recommended patients who recovered after getting Covid-19 to continue to wear masks and maintain social distancing.
Similarly, the absence of lasting natural immunity would mean that those recovered from the disease would still need to get vaccinated once an effective vaccine is discovered.
“Since immunity could be non-durable (…), vaccination should also be considered for those who have gone through an episode of infection,” underlined the experts.
In mid-July, the World Health Organization (WHO) expressed hope that those recovered from Covid-19 would enjoy some degree of immunity for several months.
WHO epidemiologist Maria van Kerkhove had then underlined that in cases of other coronaviruses such as MERS and SARS the immunity lasted for some 12 months or longer.
EFE-EPA
