Why mixing vaccines could help boost immunity, says an article on Technology Review.
New trials on mixing different types of vaccines are underway
A dozen covid-19 vaccines are now being used around the world. Most require two doses, and health officials have warned against mixing and matching: the vaccines, they argue, should be administered the way they were tested in trials. But after emerging concerns about the very rare risk of blood clots linked to the Oxford-AstraZeneca vaccine, that advice may soon change.
Guidance on this issue varies from country to country. Germany and France, for example, have advised younger citizens who received the first shot to switch vaccines for their second dose. Canada, where millions of people have received their first dose of Oxford-AstraZeneca, is still deciding how to proceed.
David Masopust, an immunologist at the University of Minnesota Medical School, points out that most vaccines target the same protein. So switching vaccines should work, at least in theory.
We should soon have a better idea. A handful of trials are now underway to test the power of vaccine combinations, with the first results due later this month. If these mixed regimens prove safe and effective, countries will be able to keep the vaccine rollout moving even if supplies of one vaccine dwindle because of manufacturing delays, unforeseen shortages, or safety concerns.
But there’s another, a more exciting prospect that could be a vital part of our strategy in the future: mixing vaccines might lead to broader immunity and hamper the virus’s attempts to evade our immune systems. Eventually, a mix-and-match approach might be the best way to protect ourselves
Mixing on trial
The covid-19 vaccines currently in use protect against the virus in slightly different ways. Most target the coronavirus’s spike protein, which it uses to gain entry to our cells. But some deliver the instructions for making the protein in the form of messenger RNA (Pfizer, Moderna). Some deliver the spike protein itself (Novavax). Some use another harmless virus to ferry in the instructions for making it, like a Trojan horse (Johnson & Johnson, Oxford-AstraZeneca, Sputnik V). Some offer up whole inactivated virus (Sinopharm, Sinovac).
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Source: Technology Review
