A healthy man in his 30s has contracted the coronavirus again, about four and a half months after he was first diagnosed with the contagious disease, Hong Kong scientists report Monday, August 24.

The Hong Kong team notes that, based on genome sequencing from the first and second cases, that the strains are "clearly different." This makes the first recorded case of reinfection. However, BBC reports about the warning from the World Health Organization, stressing the importance of not jumping to conclusions "based on the case of one patient."

Hong Kong Impose Restrictions As Coronavirus Cases Continue To Rise
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HONG KONG - AUGUST 01: Cleaners sweep the floor ahead of the first lot of patients' arrival at Asia World-Expo on August 1, 2020, in Hong Kong, China. AsiaWorld-Expo has been converted into a makeshift hospital that can take up to 500 patients. A group of seven mainland health officials will arrive in Hong Kong on Sunday as the first members of a 60-strong team that will assist with testing for Covid-19 as the city is expected to record more than 100 new confirmed cases on Saturday, the 11th day in a row with triple-digit increases.

Different Strain, Different Response

The patient in question is a 33-year-old man who came back to Hong Kong from Spain, passing through the United Kingdom. In the report, there was also a gap of 142 days between the first and second cases.

Experts say that the reinfection was unexpected since millions of people have already been infected with the coronavirus across the world. Others inferred that reinfections might not be rare at all and are not necessarily serious.

In fact, the 33-year-old Hong Kong man showed no symptoms during his second case of COVID-19. It suggests that who;e his previous exposure to the virus did not result in immunity, allowing reinfection, his immunity somehow kept the coronavirus in check.

Akiko Iwasaki, a Yale University immunologist, reviewed the Hong Kong report on behalf of The New York Times. "The second infection was completely asymptomatic - his immune response prevented the disease from getting worse," Dr. Iwasaki said. She added that it was a "textbook example" of how immunity works, saying that a natural infection in the Hong Kong man created immunity - one that "prevented disease but not reinfection."

"In order to provide herd immunity, a potent vaccine is needed to induce immunity that prevents both reinfection and disease," Dr. Iwasaki added.

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Lilian Cheng, a reporter from the South China Morning Post, posted parts of the Hong Kong reinfection report on Twitter. The report has been submitted and is set to be published in the next Clinical Infectious Diseases journal. In the discussion of the results, they said that evidence supports that the second case of COVID-19 was by re-infection instead of prolonged viral shedding.


Coronavirus Mutations

SARS-CoV-2, which causes the Novel Coronavirus Disease (COVID-19), has been continuously studied by researchers around the world. The PHG Foundation explains that an understanding of the coronavirus genome and monitoring its mutations is important to understand its behavior and offer insights on the potential impact in terms of severity and transmission.

After the coronavirus onset in Chicago back in January, infectious-disease specialist Egon Ozer from the School of Medicine at Northwestern University first identified a recurring mutation in coronavirus strains. A recently published study, led by researchers from the Los Alamos National Library, tracks these mutations in SARS-CoV-2.

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A variant that possesses the spike protein designated as G614, has replaced the D614 as the most dominant form. In the study, researchers found out that patients who carried the G variant have significantly higher concentrations of the virus in their body, which makes them more likely to spread the coronavirus to others.

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