According to a new South Korean study, patients who test positive after recovering from Covid-19 are not contagious. Virus remnants identified in their blood would be non-viral or dead particles.
Finally some good news about Covid-19. Since South Korea reported a possible reinfection of recovered coronavirus patients, the whole world has been waiting for the results of follow-up studies. Today the results released by the Korea Centers for Disease Control and Prevention May 19 all come to reassure us. According to the researchers, these patients retested positive would not be contagious.
To reach this happy conclusion, the researchers followed 285 patients infected with the coronavirus, tested negative then new positives up to 82 days later after the disappearance of their symptoms. The virus samples taken could not be grown in culture. Also, these are non-infectious or dead viral particles, welcome the researchers. It must therefore be understood that these patients would not have been reinfected and would therefore not be contagious again.
As a result, “under the new protocols, no additional testing is required for cases that have been released from isolation”, the Korea CDC said in a report. The agency said it will now call cases “re-positive”PCR redetected after release from isolation”. The South Korean authorities have decided that a negative test for Covid-19 is no longer essential before returning to work or school for recovered patients and at the end of the confinement period.
dead cells
This study goes in the same direction as the explanations of Maria Van Kerkhove, one of the persons in charge of the management of the pandemic at the WHO. Asked about these cases of recovered patients who tested positive again, she indicated at the beginning of May that it was dead cells in the lungs which rose in the body and led to the positive test.
She also agrees with the words of Zhang Boli, president of the University of Traditional Chinese Medicine in Tianjin, according to whom the sequencing of the genome of the remaining virus of certain patients cured of Covid showed that the virus was dead. According to him, this could suggest that only traces of the genetic material of SARS-CoV2 remained in the bodies of the patients.
Finally, the results of the present study could also contribute to debates about antibody tests, which look for markers in the blood indicating exposure to SARS-CoV-2. At present, while experts believe that antibodies probably confer some level of protection against the virus, they don’t yet have solid evidence on this and don’t know how long immunity might last.
A serological test measuring the degree of immunity?
At the end of April, the Institut Pasteur announced that it had developed a “serology test capable of specifying the degree of immunity of patients cured of CoV2”. Unlike existing serological tests which only detect the presence of antibodies in the body after infection with the coronavirus, this blood test will provide information on the effectiveness of these. Thus, this tool would be able to classify the degrees of immunity into three categories: strong neutralizing, weak and non-neutralizing.
“We have developed a ‘sero-neutralization’ test which detects antibodies but above all which measures their ability to inhibit the entry of the virus into a cell”explained the founder and scientific director of TheraVectys, the virologist Pierre Charneau, to Release. It remains to be seen when this test will be approved by the health authorities and will arrive on the market.
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