Mixing Vaccines: AstraZeneca With Pfizer ‘Safe And Effective’

Madrid: Given the shortage of vaccines, especially in a populous country like India, experts have been trying to ascertain whether mixing vaccines is advisable.


A study conducted in Spain revealed that administering Pfizer mRNA COVID-19 vaccine in a person after he or she took Oxford-AstraZeneca as the first dose is highly safe as well as effective.

About a week ago, early findings from another study found that mixing the same two vaccines led to increased side-effects like fatigue and headaches among patients.

As per preliminary findings of the latest research, conducted by Spain’s state-backed Carlos III Health Institute, 30 to 40 times higher presence of IgG antibodies were detected in people who had received Pfizer vaccine as the second dose than in a monitored group of people who had just received the first dose of Oxford-AstraZeneca vaccine.

It was found that the second dose of AstraZeneca vaccine doubled the presence of neutralising antibodies, whereas a second dose of Pfizer jab after first dose of AstraZeneca vaccine pushed up up these antibodies sevenfold.

The study involved 670 people in the age group of 18-59, who had received the first dose of AstraZeneca vaccine. About 450 of them were administered the Pfizer jab as second dose.

According to one of the researchers Dr Magdalena Campins, less than 2% of the participants reported severe side-effects like headache, muscle pain and general malaise. But these symptoms can’t be categorized as serious.

“These results support the possibility of vaccinating patients who have received the first dose from AstraZeneca, but the decision is not up to the investigators of this study,” said Jesus Antonio Frias, clinical director at Carlos III.

Get real time updates directly on you device, subscribe now.

Comments are closed.