Antibodies in people recovered after the novel coronavirus infection may remain up to six months while there is no proof yet that they retain a protective effect, the press service of the European University at St. Petersburg said, reporting on the results of a study by its researchers on Friday, as reported by TASS.
“Within the framework of a study, repeated tests were conducted on the participants of the first stage of the study held in spring and summer. Out of 95 participants with antibodies detected in spring and summer, in 92 the antibodies were detected again, at least by one of the two tests, SARS-CoV-2-IgG-IFA-BEST or Abbott Architect IgG. The interval between the two tests was 4-6 months,” the statement said.
The study co-author, epidemiologist Anton Barchuk noted that it is still early to say that a positive test indicates a long-term protection. “Yet we were surprised that the antibodies were still detected almost in all the participants of the first stage. Considering that there are relatively few reports of repeat infections, this is good news,” the press service quoted the researcher as saying.
In the summer, the researchers of the European University began a representative population study of occurrence of the antibodies to the SARS-CoV-2 virus in St. Petersburg. The Scandinavia clinic, the Genetico laboratory and the Smorodintsev Research Institute of Influenza of the Russian Healthcare Ministry also took part in the study. After the first stage the scientists drew conclusions that 8% of residents in St. Petersburg have the antibodies to the novel coronavirus. The next stage was launched in October.
“After an almost two-month-long monitoring of a representative sampling of the St. Petersburg residents, about 24% with the positive test for the antibodies to the novel coronavirus were detected. A significant growth of the share of positive tests at the population level occurred in November, during the last two weeks of the study this indicator approached 30%. <…>. Thus, the number of those who had [the coronavirus] in St. Petersburg by the end of autumn comes to over 1 mln people,” the scientists explained.
According to the latest data of a study of population immunity to the novel coronavirus infection conducted by Russia’s sanitary watchdog, about 27% of observed participants among the residents of St. Petersburg have the antibodies.