Mix-and-Match COVID Vaccines Give Strong Immune Response: UK Study

The study finds immune response to be highest when AstraZeneca vaccine was followed up by a 2nd dose of Pfizer.

<div class="paragraphs"><p>The study found a strong T-cell response in participants who received a combination of AstraZeneca and Pfizer COVID vaccines</p></div>

A mix and match of AstraZeneca and Pfizer vaccines gives a strong immune response finds preliminary results of a study by Oxford University.

The preprint study in the journal Lancet, compared the immune response of mixing and matching the Pfizer and AstraZeneca vaccines in different combinations.

The interim results of the study has found that one dose of Astrazeneca followed by a second dose of Pfizer produced the highest immune response.

About the Study

Here are some key points about the study,

  • The study began in Februrary and involves 830 participants who received a combination of AstraZeneca and Pfizer vaccines.

  • The average age of these participants was 57.8 years.

  • 45.8 percent of the sample was made up of females.

  • Immune response of 463 people were studied after a month of the second dose.

  • These participants were given 2 different vaccines with a gap of 4 weeks.

  • Data for the rest of the participants, who were given the two doses with a gap of 12 weeks between them is expected next month.

  • The study examines the T-cell responses of people after receiving different combinations of the two vaccines.

What the Study Found

In May, the study authors had released preliminary results saying, it is safe to mix-and-match two different types of COVID vaccine.

The new results not only show that it is safe, but point to the performance of the vaccines being enhanced when mixed, particularly that of the AstraZeneca vaccine.

The study found the T-cell response to be highest when a first dose of AstraZeneca vaccine was followed up with a second dose of Pfize.

T cells are responsible for destroying specific pathogens and play a vital role in immune response triggered by vaccines.

Interestingly, they also found the immune response to be lower when Pfizer vaccines were followed up by AstraZeneca vaccines.

The highest antibody response however was induced by two doses of Pfizer. Two doses of AstraZeneca elicited the lowest antibody and T Cell response.

Another study conducted by the University of Oxford has found that a gap of 45 weeks between two doses of the AstraZeneca vaccine produces a far stronger immune response.

Currently, the mandated gap between vaccine doses in India is 12 - 16 weeks.

The trial results also suggest that a third booster dose for those fully vaccinated with AstraZeneca vaccines could further strengthen immunity.

Why the Findings Are Important

This findings are significant in the context of vaccine shortage and delays in rollout in many countries, and could help accelerate faltering vaccination drives.

Faced with vaccine shortage and delays, some countries including Germany and Spain, have already started using a combination of different vaccines.

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