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What happens if we mix the AstraZeneca and Pfizer vaccines?

» ProSalud

A study carried out by the Carlos III Health Institute of Spain (ISCIII) investigated what happens if we combine vaccines for the coronavirus developed by different laboratories.

The work investigated the consequences of providing a dose of Pfizer after having applied one of AstraZeneca.

676 patients from different age groups and regions of Spain who received a single dose of AstraZeneca participated in the trial.

They were separated into two groups: those who received the dose immediately and those who received it after 28 days.

The results, recently presented, are those analyzed 14 days after receiving the Pfizer dose: they demonstrated a strong immune response and mild to moderate side effects in people under 60 years of age.

In addition, the protection provided by a second Pfizer jab is even greater than if it is repeated with the same vaccine. Thus, the neutralizing antibodies that protect against SARS-CoV-2 will be multiplied by seven, while in two doses of the same drug that number is only three times more protective.

From this data, the health authorities of the different countries can determine which vaccine should be administered to those under 60 years of age who received the first dose of AstraZeneca, a group that in the Spanish case amounts to almost two million people. .

“Today's results support being able to vaccinate patients who have received the first dose of AstraZeneca, but the decision does not correspond to the researchers of this study,” said Jesús Antonio Frías, coordinator of the ISCIII Clinical Research Network.

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Jorge Camargo
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