LONDON – As the world races to vaccinate and fight new variants of Covid-19, a new test is trying something that can speed up the process: mixing doses.
Patients participating in a clinical trial launched Thursday in the UK will receive different vaccines for the first and second doses: the vaccine developed by Oxford University and AstraZeneca, followed by that from Pfizer and BioNTech, or vice versa.
The UK Department of Health said this was the first such study – patients typically receive two doses of the same vaccine – and will help determine the safety of mixing doses in different groups and at a variety of different time intervals.
The researchers said they wanted participants over 50 and not yet vaccinated to participate in the study.
The 13-month study, known as “Com-Cov”, is expected to report the first findings in the summer. Your data could lead to a change in UK vaccine policy.
In the United States, the Centers for Disease Control and Prevention recently changed the guidelines for Covid-19 vaccines, saying that patients could mix Modern and Pfizer doses in “exceptional situations”.
But the Pfizer and Moderna vaccines are based on the same messenger RNA, or mRNA, platform. The UK study, however, involves mixing vaccines based on different techniques. The AstraZeneca / Oxford vaccine uses an inactivated adenovirus, a type of virus that causes the common cold.
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Test participants will be tested to monitor their levels of antibodies and T cells, which look for and attack infected cells.
“This is an extremely important clinical trial that will provide us with more vital evidence about the safety of these vaccines when used in different ways,” Nadhim Zahawi, minister for Covid-19 vaccine implantation, said in a statement.
Professor Jonathan Van-Tam, the UK’s deputy medical director and responsible for the study, said there are “definite advantages to having data that can support a more flexible immunization program”.
“It is also possible that when combining vaccines, the immune response can be increased, giving even higher levels of antibodies that last longer; unless this is evaluated in a clinical trial, we simply won’t know,” he added.
The UK faced criticism for delaying the second dose of the vaccine for some patients by up to 12 weeks, instead of the recommended 21 days, in order to prioritize the administration of as many first doses as possible.
But Health Secretary Matt Hancock this week pointed to new research, which has not yet been peer-reviewed, which suggests that patients have high immune resistance to Covid and reduced transmission after just one dose.
Vaccine shortages and distribution problems have been reported in the United States, while many countries in the European Union are also receiving far fewer doses than expected.
The Oxford / AstraZeneca vaccine has not yet been approved in the United States, despite approvals in the United Kingdom and elsewhere, although Germany, Sweden, Austria and Poland recommend not administering it to people over 65 due to test data inconclusive.
The results of the phase 3 trial last week showed that a vaccine developed by Johnson & Johnson and Janssen Pharmaceuticals provided effective protection against Covid with an injection.
So far, the UK has vaccinated more than 10 million of its 66 million citizens and its government aims to have vaccinated 15 million, including the most vulnerable groups, by 15 February.
With more than 109,000 Covid-related deaths to date, the UK has the fifth highest number of pandemic deaths in the world.
The four nations with the most deaths, India, Brazil, Mexico and the USA, all have much larger populations.
The death toll in the U.S. is now over 450,000, according to the latest count from NBC News.