Scientists from the United States found that three months after vaccination with Pfizer and Moderna drugs, the humoral — antibody-related immune response to COVID-19 decreases. The researchers ‘ article was published in the journal Scientific Reports.

Scientists from Northwestern University tested blood samples of 27 adults — 13 with a positive test for coronavirus and 14 healthy ones. The study participants donated blood three times: the first time two to three weeks after the first dose of the vaccine, the second time the same period after the second, and the third time two months after it. The researchers evaluated the level of antibodies in the blood and how effectively they block the binding of the coronavirus peplomer protein from ACE2 receptors over time — the main mechanism for the penetration of SARS-CoV-2 into the cell.

The level of antibody production in the blood of participants significantly decreased over three months. The average level of antibody suppression three weeks after the second dose was 98 percent, but after three months it decreased by 20 percent. The humoral immune response in those who had been ill with COVID-19 was expected to be higher. However, it was found that in those who suffered the disease asymptomatically, it was comparable to that in people with a negative test for COVID-19.

The humoral immune response to new strains of coronavirus was lower-three weeks after the second dose of the vaccine, the level of blocking of the peplomer protein for the”gamma” strain was 70 percent, and for the “beta”strain-67. After three months, these figures decreased by 31 and 27.5 percent, respectively.