UK Considers ‘Mix and Match’ Approach for COVID-19 Vaccine Doses

The United Kingdom authorised two COVID-19 vaccine candidates for emergency use in December 2020: Pfizer-BioNTech’s vaccine and the Oxford-AstraZeneca vaccine.

If need be or in specific circumstances, the British government has suggested that people may mix and match their two COVID-19 shots, according to a report by Business Insider.

The latest guidelines for vaccine providers read,

“For individuals who started the schedule and who attend for vaccination at a site where the same vaccine is not available, or if the first product received is unknown, it is reasonable to offer one dose of the locally available product to complete the schedule. This option is preferred if the individual is likely to be at immediate high risk or is considered unlikely to attend again. In these circumstances, as both the vaccines are based on the spike protein, it is likely the second dose will help to boost the response to the first dose.”

British Government’s guidelines

While the Pfizer-BioNTech candidate is a messenger-RNA vaccine and the Oxford-AstraZeneca candidate uses a viral vector technology, both involve a two-dose regimen administered several weeks apart.

Experts Point Out the Lack of Data to Support the ‘Mix and Match’ Approach

However, experts, as well as government officials, are wary of advocating such a strategy for the lack of data on its efficiency and safety - something that even the UK government acknowledges when it says that "there is no evidence on the interchangeability of the COVID-19 vaccines." The move could be risky and possibly cause harms to individuals.

Dr Phyllis Tien, an infectious disease physician at the University of California, San Francisco, told the New York Times,

“We’re kind of in this Wild West. None of this is being data-driven right now.”

Dr Phyllis Tien

Government officials in the UK would now reportedly be launching a ‘mix and match’ trial to find out if this approach could provide even better protection.

The United Kingdom has been dealing with a recent COVID surge caused by a new and potentially more infectious variant of the novel coronavirus.

"At this stage of the pandemic, prioritizing the first doses of vaccine for as many people as possible on the priority list will protect the greatest number of at risk people overall in the shortest possible time," UK officials said in a statement on Tuesday.

(With inputs from Business Insider)