AsianScientist (Aug. 26, 2020) – A 33-year-old resident of Hong Kong is the world’s first documented case of COVID-19 reinfection, with the second episode occurring 142 days after the first. The study, set to be published in Clinical Infectious Diseases, has important implications for public health strategies against COVID-19.
Scattered reports of COVID-19 reinfection surfaced early on in the pandemic. But without clear scientific data, it remained vague whether these were cases of reinfection or drawn-out illnesses. In some instances, recovered patients falsely tested positive after screening picked up traces of dead virus fragments. Despite this, experts have long suspected that immunity to SARS-CoV-2—the virus that causes COVID-19—may be fleeting, as studies have shown that immunity to other coronaviruses like SARS-CoV and MERS lasts a few years at most.
During the first round of infection, the patient presented with mild COVID-19 symptoms: cough, sore throat, headache and fever—eventually testing positive for the coronavirus on 26 March. Two weeks and two negative RT-PCR tests later, he was discharged from the hospital.
Less than five months after his initial infection, the coronavirus struck again. Returning to Hong Kong on 15 August via the United Kingdom after traveling in Spain, the patient tested positive once more during entry screening at the Hong Kong airport despite showing no symptoms this time around.
To make sense of this mystery, a team led by Professor Yuen Kwok-Yung from the University of Hong Kong analyzed specimens collected from the patient during both bouts of coronavirus infection. Through next generation sequencing, the researchers found that each infection was caused by a unique strain of SARS-CoV-2.
In fact, there was a 24-nucleotide difference between the viruses from the first and second episode, resulting in amino acid changes in nine proteins. Further genetic analysis showed that the first viral genome was closely related to earlier strains present in the US or England, while the second was closely related to strains collected from Europe in July and August.
According to the authors, their results show that achieving herd immunity is unlikely to fully eradicate COVID-19. But subsequent infections may be milder or even asymptomatic. In the case of the 33 year-old patient, while his residual antibodies were not able to prevent reinfection, they may have partially controlled the disease.
Given that reinfection is possible, the authors state that recovered COVID-19 patients should also be considered for vaccine programs. They also recommend that individuals previously infected with COVID-19 continue to comply with precautionary measures such as wearing face masks and practicing safe distancing.
“Our findings suggest that SARS-CoV-2 may persist in humans as is the case for other common-cold associated human coronaviruses, even if patients have acquired immunity via natural infection or via vaccination,” the authors said in a press statement. “Further studies on reinfection, which will be vital for the research and development of more effective vaccines, are warranted.”
Copyright: Asian Scientist Magazine; Photo: NIAID/Flickr/CC.
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