Coronavirus: Amid a sputtering vaccine rollout, an onslaught of cases and fears of a new, highly transmissible variant of the coronavirus, Britain has quietly updated its vaccination playbook to allow for a mix-and-match vaccine regimen. If a second dose of the vaccine a patient originally received isn’t available, or if the manufacturer of the first shot isn’t known, health officials said, another vaccine may be substituted.

But it is far from certain that the vaccines are so interchangeable, several researchers warned.

“There are no data on this idea whatsoever,” said John Moore, a vaccine expert at Cornell University. Officials in Britain “seem to have abandoned science completely now and are just trying to guess their way out of a mess.”

In a separate, controversial move, the British government this week also decided to front-load its vaccine rollout, delivering as many first doses to people as possible — a decision that could delay second shots up to 12 weeks.

Britain, which is seeing tens of thousands of new infections reported each day, has issued emergency authorizations for two vaccines, one developed by Pfizer and BioNTech and the other by the University of Oxford and AstraZeneca. According to the new guidance, “every effort should be made” to complete a dosing regimen with the same shot first used. But when “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” the second time around.

“This option is preferred if the individual is likely to be at immediate high risk or is considered unlikely to attend again,” the recommendations say. Because both vaccines target the spike protein of the coronavirus, “it is likely the second dose will help to boost the response to the first dose.”

The new guidance contradicts guidelines in the United States, where the Centers for Disease Control and Prevention has noted that the authorized Covid-19 vaccines “are not interchangeable,” and that “the safety and efficacy of a mixed-product series have not been evaluated. Both doses of the series should be completed with the same product.”

Some scientists say Britain is gambling with its new guidance. “None of this is being data driven right now,” said Dr. Phyllis Tien, an infectious disease physician at the University of California, San Francisco. “We’re kind of in this Wild West.”

— Katherine J. Wu The New York Times
Me: Mixing the vaccine you get, so that the 1st and the 2nd are different vaccines, seems like playing Russian Roulette with peoples lives, to me – so it seems that the English have been vaccinating without a record anywhere, of who got which vaccine and the end results might be even worse than the virus itself – bearing in mind the manufacturers have said you cannot mix vaccines!!
The vaccine from Cambridge, is said to have the lowest protection and is the cheapest to make, so why inject anyone with a vaccine which at best, probably only gives 50% protection against the virus and 50% or less zero protection ?