Researchers in Hong Kong have detected the first confirmed case of reinfection in a coronavirus patient who tested positive for the virus again after recovering.
The 33-year-old had first contracted SARS-CoV-2 in late March but tested positive a second time in August, more than four months after he recovered.
“An apparently young and healthy patient had a second case of Covid-19 infection which was diagnosed 4.5 months after the first episode,” the University of Hong Kong researchers said on Monday.
“This is the world’s first documentation of a patient who recovered from COVID-19 but got another episode of COVID-19 afterwards.
“Before this report, many believe that recovered COVID-19 patients have immunity against re-infection, however, there is evidence that some patients have a waning antibody level after few months.”
Many people have tested positive for the coronavirus a second time, but none of these have any scientific backing.
There have also been concerns about loopholes in subsequent diagnoses that confirmed them negative.
Unlike these previous cases believed to be reinfection, the researchers at the University of Hong Kong sequenced the virus from the patient’s two infections and found that they did not match.
This means that the second infection was not as a result of the first as both are not tied to each other.
The patient, who had experienced mild symptoms when he first contracted the virus, is said to not to be experiencing any symptom this time.
While there are still questions about how long COVID-19 patients can be protected after recovery, the new case of reinfection casts doubt on claims about survivors developing immunity for the virus.
More importantly, it may affect vaccines being developed regarding how long they can be effective.
Some scientists are arguing that the patient’s case “could be an outlier among the tens of millions of cases around the world and that immune protection may generally last longer than just a few months.”
Reactin g to the issue, Maria Van Kerkhove of the World Health Organisation, said: “What we are learning about infection is that people do develop an immune response, and what is not completely clear yet is how strong that immune response is and for how long that immune response lasts.”