Researchers Hong Kong: recontamination with corona established for the first time

A 33-year-old man in Hong Kong has been infected with SARS-CoV-2 for the second time. Researchers from the University of Hong Kong have established this with certainty. They genetically examined viral material from the first time the man was infected in April and did so again when the man tested positive for the coronavirus a second time this month

The virus material of April turned out to be slightly different from that of August. That means irrefutable proof that the man has been infected twice by a slightly different strain of virus. The renowned journal Clinical Infectious Diseases has now accepted the researchers’ article about their findings.

The scientists, led by Professor Kwok-Yung Yuen, draw a little hopeful conclusion based on their research. “Our research results suggest that SARS-CoV-2 may continue to circulate among the population despite herd immunity due to infections.” That would mean that SARS-CoV-2 behaves like the common cold viruses circulating.

In April, the man from Hong Kong working in the IT sector had few symptoms, in August none at all. The researchers believe that re-infections could be milder than initial infections, as is the case with this patient. Previously something similar has been observed in research on rhesus monkeys.


People who have recovered from covid-19 sometimes continued to test positive for SARS-CoV-2 for weeks. Until now, there was doubt as to whether these tests showed traces of the virus that were still in the body or whether they were new infections. In the man in Hong Kong, such a re-infection has therefore been established for the first time with certainty.

Van Kerkhove says that most of the now 24 million covid-19 patients – including those with mild symptoms – do build up immunity. But in her opinion it is not clear how long that immune response will last and how strong it is.

Genetic profiling

No one knows if these cases involve people who excrete a virus over a long period of time or people who have contracted a new infection from another strain of virus. This ambiguity can only be resolved by creating a genetic profile of the virus at different times


According to the researchers, their findings also have consequences for vaccination policy if there is a vaccine against SARS-CoV-2 in the future.

“Vaccination should also be considered for people with a known history of covid-19”, the researchers write in their article. “Patients with previous covid-19 infection should also comply with epidemiological control measures such as general use of mouth masks and social distancing.”