Each week, OMRF President Dr. Stephen Prescott opens “Adam’s Journal” to answer a medical question from OMRF Senior Vice President and General Counsel Adam Cohen.
In an ideal world, people who received the first dose of the Pfizer Covid-19 vaccine would receive the second dose of that same vaccine. Ditto with the Moderna vaccine.
However, as we all know, we don’t live in an ideal world. So, if you’ve been vaccinated with the first dose of one vaccine and get the chance to receive a second dose of the other, should you take it?
Dr. Prescott Prescribes
The short answer: We don’t yet know, so if at all possible, stick with the same vaccine for both shots.
The longer answer is that researchers in the United Kingdom have just launched a clinical trial to test this question. They’re expecting to have preliminary results by June.
The trial uses a different vaccine combination than what’s now available in the United States: one shot will be the AstraZeneca vaccine that’s not yet approved by the FDA, and the other will be Pfizer. But the findings should apply to other vaccine combinations, and many immunologists believe this approach could actually produce a more robust immune response than two doses of the same vaccine.
By combining shots that program the immune system to recognize and repel a pathogen in slightly different ways, the body might better arm the immune system to turn back invaders. Known technically as heterologous prime-boost vaccination, this mix-and-match approach has proven effective against other infectious diseases, including Ebola, malaria and tuberculosis, and also in cancer treatment and prevention.
Last month, Oxford University scientists reported that the mix-and-match approach using a pair of Covid-19 vaccines generated strong immune responses in mice. If these findings hold true in humans, health authorities could get people fully vaccinated more quickly and effectively, especially as additional new vaccines come online in the coming months.
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