A group of Hong Kong researchers claimed on Monday to have discovered the first proven case in the world of reinfection with COVID-19, although several experts stressed that this does not allow to draw conclusions about the evolution of the pandemic.
“This case shows that it is possible to be reinfected only a few months after having been cured of a first infection,” the department of microbiology at the University of Hong Kong (HKU) said in a statement.
The patient in question, a 33-year-old man living in Hong Kong, was infected twice in the span of four and a half months, according to the note.
“Patients who have already suffered from COVID-19 must bear in mind that they can become infected again and must respect physical distancing, wear a mask and wash their hands,” one of the study’s authors, Kelvin Kai-Wang To, told AFP.
“This case shows that it could be very difficult to eliminate COVID-19 since the virus can circulate among the population and reinfect people,” as other coronaviruses responsible for common colds do, he added.
The researchers noted that a genetic analysis showed that the two successive infections were caused by two different strains of the SARS-CoV-2 virus, responsible for COVID-19.
“Since immunity may not last long after infection, vaccination should be considered even for those who have already been infected,” they judged.
And at the same time, “vaccines may not be able to guarantee lifelong protection against covid-19,” they explained.
The patient tested positive for the first time on March 26, after presenting the following symptoms: cough, headache, and sore throat and fever. Once cured, he tested negative twice.
But on August 15, he was diagnosed positive again. But this time he did not present any symptoms: his disease was detected thanks to the test that was carried out at the Hong Kong airport, back from a trip to Spain via the United Kingdom.
“It is unlikely that herd immunity can eliminate SARS-CoV-2, although it is possible that later infections are less severe than the first, as was the case with this patient,” write the authors of the study, accepted Monday, as they assured, by the American medical journal Clinical Infectious Diseases, and awaiting publication.
Several cases of reinfection were announced in recent months in the world, without being proven, while the question of immunity remains surrounded by uncertainty since it is unknown, for example, to what extent the antibodies protect and the duration of the supposed immunity.
Some specialists cautioned against jumping to conclusions in light of this study.
“It is difficult to draw definitive conclusions from a single case. Considering the number of infections in the world, seeing a case of reinfection is not so surprising,” said Dr. Jeffrey Barrett, of the Wellcome Sanger Institute, in the United Kingdom, quoted by the British agency Science Media Center.
“It is not a reason to be alarmed: this illustrates wonderfully how immunity can work,” said Dr. Akiko Iwasaki, an immunity specialist at Yale University (United States), on Twitter.
“The second infection was asymptomatic. Although the immunity was not sufficient to prevent reinfection, it protected this person against the disease,” he explained.