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University of Hong Kong documents world's first case of covid-19 re-infection

People wearing masks to protect against the coronavirus, walk across a street in Hong Kong (AP)Premium
People wearing masks to protect against the coronavirus, walk across a street in Hong Kong (AP)

Putting the belief to rest that recovered covid-19 patients have immunity against re-infection because most developed a serum neutralizing antibody response, The University of Hong Kong (HKU) on Monday documented the world's first case of covid-19 re-infection

New Delhi: Putting the belief to rest that recovered covid-19 patients have immunity against re-infection because most developed a serum neutralizing antibody response, The University of Hong Kong (HKU) on Monday documented the world's first case of covid-19 re-infection.

Researchers from Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong (HKU), said that they have proven the first instance of human re-infection by SARS-CoV-2 by using the next generation sequencing.

The team showed that the genome sequence of the virus strain in the first episode of covid-19 infection is clearly different from the genome sequence of the virus strain found during second episode of infection.

The scientists have cautioned that patients with previous covid-19 infection should also comply with epidemiological control measures such as universal masking and social distancing.

“Our findings suggest that 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,"’the scientists said.

The researchers said that there is evidence that some recovered patients of covid-19 have waning antibody level after few months. Since the immunity can be short lasting after natural infection, the scientists said that vaccination should also be considered for those with one episode of infection.

“Moreover there are also reports that the virus RNA can wax and wane in the respiratory secretions of convalescent patients for up to 3 months," said the statement adding that it is unclear whether these patients are prolonged virus shedders or have re-infection by another strain of SARS-CoV-2 as no viral genome sequencing is performed to differentiate these two possibilities.

The work has been accepted by the international medical journal Clinical Infectious Diseases on 24 August 2020, HKU said in a press statement.

The researched reviewed an apparently young and healthy patient had a second episode of covid-19 infection which was diagnosed 4.5 months after the first episode.

Viral genomes from first and second episodes belong to different clades/lineages. A total of 24 nucleotides were different between the viruses from the first and second episode. Amino acid differences can be found be found in 9 proteins, including a 58-amino acid truncation of ORF8 protein that was present only in the virus from the first infection, the researchers found.

“This case illustrates that re-infection can occur just after a few months of recovery from the first infection," said the statement.

The research team included Dr. Kelvin Kai-Wang To, Clinical Associate Professor, Department of Microbiology, Li Ka Shing Faculty of Medicine, HKU, Professor Ivan Fan-Ngai Hung, Clinical Professor, Department of Medicine, Li Ka Shing Faculty of Medicine, HKU, Professor Kwok-Yung Yuen, Henry Fok Professor in Infectious Diseases, Chair Professor of Department of Microbiology, Li Ka Shing Faculty of Medicine, HKU, Co-Director of the State Key Laboratory of Emerging, Infectious Diseases and Academician of the Chinese and the Academy of Engineering.

The research has raised alarm bells in India.

“This raises concern for all of us as we are dealing with this new virus and none of us really know how this will behave in the long run," said Dr Shuchin Bajaj, fighting covid at Project StepOne, an empanelled partner for telemedicine consultations on Aarogya Setu Mitr.

Bajaj recounted his experiences that he has seen that the plasma donors who come to the hospitals some of them do not have any antibodies as well and some have good anti body level when they come to donate the first time but then the anti bodies ate completely negligible when they come for the second or the third time or if they come to donate after 1-2 months of infection.

“Definitely this is evident that immunity is not very long lasting and anti bodies level do go down. If reinfections are happening then that means we have to live and fight with this virus for a very long long time to come," said Bajaj.

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