Covid19 Vaccine : AstraZeneca shot followed by Pfizer provides strong immunity – Study
Mixing doses of Covid-19 vaccines from Pfizer Inc. and AstraZeneca Plc creates a strong immune response, according to results from a University of Oxford study, a finding that could enable greater flexibility in the use of scarce supplies.
A mixed schedule of the Pfizer shot followed by the Astra vaccine, and vice versa, resulted in high concentrations of antibodies against Covid-19 when given four weeks apart, researchers reported in the Lancet medical journal. The order in which people got the vaccines affected the results. Astra followed by Pfizer produced higher levels of immune antibodies and T-cells than Pfizer followed by Astra.
An AstraZeneca shot followed by Pfizer produced the best T-cell responses, the team found, and also a higher antibody response than Pfizer followed by AstraZeneca. The results were for two doses of different vaccine combinations, given at four-week intervals to 830 people, in a participant-blind, non-inferiority trial a type of study used to demonstrate that an experimental treatment is not substantially worse than an active treatment it’s being compared to.
The Covid vaccines currently authorized in the U.K. and U.S. stimulate our immune systems into generating antibodies to protect us from infection. Antibodies are produced by specialized white blood cells called B lymphocytes or B-cells. T-cells, meanwhile, are a second type of white blood cell that also plays an important role in our immune system; T-cells can both attack cells which have been infected with a pathogen or virus, such as Covid, and also help B-cells to produce antibodies.
