Residents don face masks in Hung Hom, Hong Kong, Aug 13, 2020. (WANG SHEN/XINHUA)

HONG KONG - More research evidence is needed to validate the world’s first case of coronavirus reinfection, a leading mainland infectious disease expert said on Tuesday.

Mainland expert Zhang Wenhong shared his views with China Daily a day after a Hong Kong resident was learnt to have contracted a different coronavirus strain from the one he had previously contracted and recovered from an initial bout in April. He remained asymptomatic for the second infection.

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Mainland expert Zhang Wenhong said if there were no more reports of reinfection in Hong Kong or elsewhere, the Hong Kong patient's case could be treated as an isolated incident

According to researchers at the University of Hong Kong (HKU), it is the first documented instance of human reinfection of the coronavirus.

The man, in his 30s, tested positive on returning to Hong Kong from Europe this month, indicating that it was a reinfection rather than a relapse, according to the HKU research team.

Zhang, director of the department of infectious diseases at Shanghai Huashan Hospital Affiliated with Fudan University, said if there were no more reports of reinfection in Hong Kong or elsewhere, the Hong Kong patient's case could be treated as an isolated incident.

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

The researchers include Yuen Kwok-yung, chair professor of the Department of Microbiology at HKU, and To Kai-wang, clinical associate professor with the Department of Microbiology of the university.

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In a blog posted on Tuesday, Zhang said in cases of relapse on the mainland, Hong Kong and elsewhere, residues of non-transmissible nucleic acid with little medical significance had been found.

He said more research was needed in the Hong Kong patient's case to ascertain whether nucleic acid residues or live virus had contributed to the positive test result. If live virus is found, studies would be needed in order to compare the genetic sequences of nucleic acids of the strains of the virus that caused the two instances of infection, the medical expert said.

“We cannot base our conclusion on news reports,” Zhang said. He pointed out how reports of reinfection in the US had not been supported by scientific studies.

If reinfection does occur, regions experiencing massive coronavirus outbreaks could be susceptible, Zhang said.

He said it was most unusual that the Hong Kong patient had contracted the infection within four and a half months of recovering as immunity following an infection usually lasted longer.

Meanwhile, Yuen said vaccination is still the most pragmatic and important way to fight the pandemic, calling on the public to wear masks, keep social distancing and observe hand hygiene.  

With inputs from Xinhua