Researchers at Oxford University in the UK will begin testing what happens when they give people a mixture of different COVID-19 vaccines.
Amid a shortage of vaccine supplies and the threat of emerging coronavirus variants, such an approach could provide an answer for both, according to a statement. The study, which will include more than 800 volunteers in England who are 50 years or older, is the first to analyze a mix-and-match approach to COVID-19 vaccination.
Some participants receive a first dose of Oxford-AstraZeneca vaccine, followed by a second dose of the same vaccine or the Pfizer vaccine; and some receive the Pfizer vaccine, followed by a second dose of the same vaccine or the Oxford-AstraZeneca vaccine.
Related: Quick guide: COVID-19 vaccines used and how they work
Some participants receive the two doses four weeks apart, and others receive the vaccines twelve weeks apart (which is in line with UK policy to vaccinate as many people as possible and delay the second dose by 12 weeks). The participants will all periodically give blood samples and the researchers will test the impact of mixing and adaptation on their immune responses, and will also test for any adverse reactions.
Given the inevitable challenges of immunizing a large number of populations against COVID-19 and potential constraints on the global supply, there are definite benefits to having data that can support a more flexible vaccination program, if necessary and if approved by the drug regulator, “Dr Jonathan Van-Tam, the deputy chief medical officer and senior officer responsible for the study, said in the statement. “It is also possible that by combining vaccines the immune response can be improved, which can yield even higher antibody levels that last longer; unless evaluated in a clinical study, we just will not know.”
The Oxford-AstraZeneca and Pfizer vaccines have been developed using two different approaches; To stimulate the immune system, the former uses an attenuated adenovirus to deliver the genes from the vein protein and the latter uses messenger RNA wrapped in a nanoparticle.
It is not yet clear whether the granting of two very different vaccines could be of any benefit. The closest information on this is the Russian Sputnik V vaccine, which was 91% effective in preventing COVID-19 and, according to the Associated Press, uses two slightly different versions of its vaccine for its two different doses. Yet both versions were developed using the same adenovirus-based technology.
Indeed, if the study shows that a mix-and-match approach offers great benefits, it will still be formally reviewed by the Medicines and Healthcare Products Regulatory Agency (MHRA) for safety and efficacy before the rest of the public.
Currently, the UK and US guidelines state that COVID-19 vaccines should not be used interchangeably unless the same type of vaccine is not available for someone’s second dose, or if it is unknown which vaccine the person is taking. received first dose, according to the AP.
The mix-and-match trial is being conducted by the UK’s National Immunization Schedule Evaluation Consortium with state funding and will last 13 months.
Originally published on Live Science.