Nearly 100 percent of people developed COVID-19 antibodies after receiving their second dose of the Pfizer or AstraZeneca vaccine in the U.K., according to new research from the National Health Service and University College London.
The preliminary findings, released May 14, are based on an analysis of 13,232 antibody samples from more than 8,500 people in England and Wales.
Researchers found 96.42 percent of study participants had antibodies 28 to 34 days after their first dose. This figure jumped to 99.08 percent seven to 14 days after their second dose.
Antibody positivity rates increased faster among people who received the Pfizer vaccine compared to the AstraZeneca vaccine, which has not been authorized for use in the U.S. Antibody rates were equivalent for both vaccines about four weeks after the first dose.
Antibody rates were lower with increasing age and among people with health conditions such as diabetes, heart disease and cancer, but nearly all study participants demonstrated high antibody levels after their second dose.
The findings come as the U.K. has been delaying second COVID-19 vaccine doses to vaccinate a larger number of people more quickly, reports The Hill.