What Happens When You Mix 2 Vaccine Shots? A Study Has Found This

Researchers and public health officials are examining strategies such as blending two different shots as many low- and middle-income nations try to figure out how to cope with vaccine scarcity.

Mixing doses of two leading Covid-19 vaccines increased patients' side effects such as fatigue and headaches in early findings from a study that has yet to show how well such a cocktail defends against the virus. People who got a first dose of AstraZeneca Plc's shot followed by Pfizer Inc.'s vaccine four weeks later reported more short-lived side effects, most of them mild, researchers from the University of Oxford reported in The Lancet medical journal. That was also true when the order of the shots was switched. Researchers and public health officials are examining strategies such as blending two different shots as many low- and middle-income nations try to figure out how to cope with vaccine scarcity. Assurance that mismatched shots are still safe and effective would make it easier for governments to manage their stockpiles and provide more insight into a combination that's already used in some countries. In France, for instance, people who got a first dose of the Astra vaccine before the government restricted it to older patients are being offered the vaccine developed by Pfizer and BioNTech SE for their second injection.