American scientists from the Institute of Public Health, the University of Texas Health Science Center and the Veterans Affairs Medical Center analyzed the effectiveness of covid vaccination among 780,225 veterans.
A decrease in immune protection was recorded from February to October, during the period of the spread of the delta strain of coronavirus, according to Science. The new strain led to an increase in breakthrough infections when covid symptoms appeared in vaccinated patients. Johnson & Johnson's Janssen vaccine decreased the most (from 86.4% to 13.1%). PfizerBioNTech also shows a decrease in efficiency (from 86.9% to 43.3%). For Moderna, this figure dropped from 89.2% to 58%.
According to scientists, vaccines of any type provide significant protection against deaths.