Immunologist Kryuchkov suggested issuing QR codes depending on the level of antibodies from COVID-19 
Antibodies are an indicator of specific immunity, which directly correlates with a degree of protection against COVID-19. Because of this, people with high antibody levels can be given QR codes. So commented on the idea previously voiced by the head of Rospotrebnadzor Anna Popova, immunologist, candidate of medical sciences Nikolai Kryuchkov in an interview with Izvestia.
According to him, in Russia there are a large number of people who have had coronavirus who did not seek medical help … A high level of antibodies will allow them to be issued certificates.
According to the immunologist, the validity of such QR codes should depend on the level of antibodies. He proposed to start issuing QR codes with an antibody titer of 300 Bau/milligram for a maximum of two months, at a level of 500 to 800 Bau/milligram for two to three months, more than a thousand Bau/milligram for three to four months, and from 1500 to 2000-2200 Bau/milligram – for five months.
“In this case, antibodies should not be any, but only immunoglobulins G,” the specialist noted.
that the Russian authorities are discussing the possibility of issuing QR codes to citizens who have a sufficient level of antibodies to COVID-19, the head of Rospotrebnadzor Anna Popova said on November 17. Later, the Telegram channel “Earlier than all. Well, almost, ”referring to a source on the site under the Cabinet of Ministers, said that the government has already determined the level of antibodies required to obtain a QR code – 350-500 Bau/ml. There has been no official statement about this yet.