Mixing doses of AstraZeneca and Pfizer increases defenses against covid-19 by up to six times

Taking the first dose of AstraZeneca and the second dose of Pfizer produces a stronger immune response than both taking AstraZeneca. These are the results of a new study sponsored by the KDCA, the Korea Agency for Disease Control and Prevention, in South Korea, citing South Korea’s Yonhap Agency.

499 healthcare professionals were studied – 100 received mixed doses, 200 received two doses from Pfizer, and the remaining 199 received two injections of AstraZeneca. They all showed antibodies, but those who mixed the two vaccines created six times more defenses against Covid-19 than those who took two doses of AstraZeneca.

Mixing the vaccines had similar results for those who received the two doses from Pfizer. The study looked at neutralizing activity against key covid-19 variants. Neither group reduced its activity against the alpha variant, but neutralization did indeed decrease 2.5–6-fold against the beta, gamma and delta mutants.

Giving doses of different vaccines, according to zap.aeiou.pt, has been a possibility on the table for some time in some European countries, with German Chancellor Angela Merkel, after taking the first dose of AstraZeneca and a second talking.

Another Oxford University study, published in June, reached similar conclusions. The effects of administration of the first dose of AstraZeneca and the second dose of Pfizer were analyzed in 830 volunteers over the age of 50 years. The researchers concluded that this combination produces more antibodies and better T-cell responses rather than switching the order of dosing.

The Oxford study also showed that the Pfizer vaccine produced 10 times more antibodies than AstraZeneca and that everyone who received one dose of AstraZeneca and then one dose of Pfizer had as strong a response as anyone who took both from Pfizer.

The text was originally published in the print edition of Expresso das Ilhas nº 1026 on July 28, 2021.