Mixing AstraZeneca And Pfizer Vaccines Is Effective Against COVID-19, According To Recent Study

Mixing AstraZeneca And Pfizer Vaccines Is Effective Against COVID-19, According To Recent Study
Image by Mufid Majnun / Unsplash

As the battle against COVID-19 continues, researchers are looking for ways to improve the efficacy of vaccine programs around the world. In fact, a paper published on The Lancet pre-print reports that a combination of Oxford-AstraZeneca and Pfizer-BioNTech COVID-19 vaccines produces a strong immune response against the virus.

The Com-Cov trial (Comparing COVID-19 Vaccine Schedule Combinations), led by the University of Oxford Vaccine Group, looked into the efficacy of the “mix-and-match” approach, wherein an individual will receive two different brands of approved COVID-19 vaccines for the first and second doses, which could possibly address a supply shortage.

The study examines the body’s T cell immunity. T cells, a type of white blood cell that the bone marrow produces, are crucial in the production of antibodies. Additionally, another type of T cell also kills cells infected by the virus.

According to their findings, two doses of the Pfizer-BioNTech jab produced the highest level of antibodies. However, one Oxford-AstraZeneca shot, followed by a second dose of the Pfizer-BioNTech vaccine, generated a response that was nearly as potent. The doses were given four weeks apart.

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They also tested different combinations, but those who had a Pfizer shot followed by an AstraZeneca booster produced antibody levels nearly seven times lower than those who had two shots of Pfizer. But the good news is, this still produced antibody levels that are five times higher than two jabs of AstraZeneca.

“Both ‘mixed’ schedules (Pfizer-BioNTech followed by Oxford-AstraZeneca, and Oxford-AstraZeneca followed by Pfizer-BioNTech) induced high concentrations of antibodies against the SARS-CoV2 spike IgG protein when doses were administered four weeks apart,” according to the researchers.

“This means all possible vaccination schedules involving the Oxford-AstraZeneca and Pfizer-BioNTech vaccines could potentially be used against COVID-19.”

Professor Matthew Snape, the lead investigator of the Com-Cov trial, says that the findings can add flexibility to vaccination programs globally. “The Com-Cov study has evaluated ‘mix and match’ combinations of the Oxford and Pfizer vaccines to see to what extent these vaccines can be used interchangeably, potentially allowing flexibility in the UK and global vaccine roll-out.”

The results of this study were recorded in 830 participants given the different vaccine combinations with a four-week interval. The University of Oxford will now be looking into the immune responses if the vaccines are to be given 12 weeks apart, since COVID-19 jabs are usually given with 8 to 12 weeks intervals in the United Kingdom. According to an article by The Guardian, further data is expected next month.

In the Philippines, inoculation using the Oxford-AstraZeneca vaccines resumed in May for all age groups, following the Department of Health’s temporary suspension of the vaccine in April. An initial finding by the European Medicines Agency reported blood clots (Vaccine-Induced Thrombosis and Thrombocytopenia) as a very rare side effect in individuals below age 60.

In June, the Philippine government signed an order agreement for the supply of 40 million doses of the Pfizer-BioNTech vaccine. Deliveries are expected to arrive in September this year.  

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The Delta Variant

The Delta variant (and a newly discovered Delta-plus mutation) of COVID-19, which was first identified in India, is known as the “most transmissible” of the variants identified so far. It is also known to be more deadly than the previous ones.

However, experts say that vaccines are still effective against this variant.

“The good news is if you are vaccinated -- and fully vaccinated means two weeks after your last shot -- then there is good evidence that you have a high degree of protection against this virus," says US Surgeon-General Dr. Vivek Murthy.

Dr. Mark Mulligan, director of the NYU Langone Vaccine Center, adds, “Vaccines can handle it. In most cases, we have a cushion of magnitude in circulating antibody and other cellular responses. The vaccines are able to handle this.”

The Philippines has reported 17 Delta cases so far. And while vaccines are highly effective against this variant, it is still best to take everyday measures seriously to prevent transmission.

Wear your masks, everyone!

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