Britain is set to allow the mixing of various coronavirus vaccines under special circumstances, despite limited knowledge on whether mixed doses provide the same amount of protection as uniform doses.
The British government released updated guidelines on New Year’s Eve that state, “[If] 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.”
Mary Ramsay, head of immunizations at Public Health England, explained that different doses of the coronavirus vaccine would be given out on extremely rare occasions, Reuters reported.
“Every effort should be made to give them the same vaccine, but where this is not possible it is better to give a second dose of another vaccine than not at all,” she said.
Britain became the first country to provide emergency use authorization for the Pfizer-BioNTech and AstraZeneca vaccines in December. Both vaccines require two doses several weeks apart, but they were not created to be paired together, Reuters reported.
According to the guidelines released by Britain, there is not yet any “evidence on the interchangeability of the COVID-19 vaccines, although studies are underway.”
The British government also raised concerns earlier this month when it announced that it would delay administering the second doses of coronavirus vaccines for 12 weeks to those who received the first shot in order to provide the initial shot, which provides limited protection from the virus, to more people, according to Reuters.
Top infectious diseases expert Anthony Fauci said at the time that he would advise against the move.
“I would not be in favor of that,” he told CNN. “We’re going to keep doing what we’re doing.”