Scientists at Ben-Gurion University of the Negev have examined the effectiveness of the Pfizer vaccine against the original coronavirus and against the British and South African strains of the disease.
Additional strains bearing different combinations of mutations that appear in the virus have also been tested.
The study findings suggest that the vaccine is effective against the original coronavirus and against the British mutation, but provides less protection against the South African version of the virus, and against variants that combine the British and South African mutations.
The data was collected from people who recovered from COVID-19, and others who were vaccinated with the first or second dose of the Pfizer vaccine. Blood samples were taken 21 days after the first dose of the vaccine, or about ten days after the second dose.
"Our findings show that the effectiveness of the vaccine against the South African strain is lower, although it still exists," says lead researcher Prof. Ran Tauba of the Department of Microbiology, Immunology and Genetics at the Faculty of Health Sciences at Ben-Gurion University of the Negev.
Prof. Tauba and his team also tested the level of neutralizing antibodies in the blood of people who recovered from the coronavirus, compared to blood taken from vaccinated people, and compared the ability of these antibodies to protect against infection with mutated strains. The findings indicate that the vaccine provides protection levels 11 times higher than the protection levels observed in patients who recovered and were not vaccinated. Also, relative to recovering patients, the first vaccine dose increased the level of protection against infection with the wild strain by 6 times, and the second vaccine dose resulted in a further 2-fold increase in the body's ability to neutralize the virus.
The study found that the effectiveness of the vaccine against the South African strain is 7 times lower relative to its effectiveness against the original strain or the British strain.