In a first such documented case, a 33-year-old Hong Kong man has tested positive for coronavirus after recovering from the same. The man tested positive for COVID-19 after returning from a trip to Spain in mid-August.
He was symptomatic the first time around, but no obvious symptoms were reported the second time, the team at the University of Hong Kong reported, as per a CNN report.
"The patient got re-infected 4.5 months after the first infection. Therefore, it shows that for this patient, the immunity induced by the first infection is short-lasting," Dr Kelvin Kai-Wang To of the University of Hong Kong, who worked on the study, said, as per the report.
The first infection was from a strain of the coronavirus most closely related to strains from the United States or England, and the second infection was most closely related to strains from Switzerland and England, researchers said.
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The findings cast doubts on claims of coronavirus immunity. The paper by the University of Hong Kong has been accepted by the journal Clinical Infectious Diseases but not yet published.
"The finding does not mean taking vaccines will be useless," Dr Kai-Wang To told Reuters. "Immunity induced by vaccination can be different from those induced by natural infection," To said.
A study published in July stated that recovered COVID-19 patients may lose their immunity to the disease within months, indicating that the novel coronavirus could reinfect people who have had it in the past, much like the common cold.
Also read: Recovered COVID-19 patients could lose immunity in months: UK study
A team from King’s College in London found that the amount of antibodies in recovered COVID-19 patients’ blood was significantly down after three months. Antibody levels fell as much as 23-fold over the period. In some cases, they became undetectable, the research revealed.
The presence of antibodies means that a person was exposed to the virus and has developed antibodies against it, which may mean that the individual has developed some immunity.
Also read: What is a COVID-19 antibody test and how to get it done? All your questions answered
Hong Kong had seen a surge in coronavirus infections in July, leading the government to implement its toughest social-distancing measures yet, which included limiting public gatherings to two people.
Since then infections have gradually declined, with the city reporting just nine infections on August 24. Overall, Hong Kong has recorded 4,692 infections, with 77 deaths.
More than 23.65 million people have been reported to be infected by the coronavirus globally and 811,895 have died, according to a Reuters tally.
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