Now, health officials in the United States are discussing this, but not everyone agrees.
Dr. Bob Wachter, the Chair of the UCSF School of Medicine, argued in favor of the policy in a thread on Twitter.
"Far better to have 100M people who are 80% protected than 50M people who are 95% protected, particularly as we are facing a foe that is getting smarter and nastier. Or at least it seems that way to me," tweeted Wachter.
U.S. is now considering idea of a single vaccination shot, delaying shot #2 until months later. Last wk, I thought that was a bad idea – the trials that found 95% efficacy were 2 shots; why add extra complexity & a new curveball. But facts on the ground demand a rethink. (1/7)— Bob Wachter (@Bob_Wachter) December 31, 2020
The idea did not immediately strike him as feasible, but he changed his mind as he watched the slower than predicted rollout combined with the arrival of the new, more transmissible variant.
He wrote, "U.S. is now considering idea of a single vaccination shot, delaying shot #2 until months later. Last wk, I thought that was a bad idea - the trials that found 95% efficacy were 2 shots; why add extra complexity & a new curveball. But facts on the ground demand a rethink."
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In the U.K., regulators recently approved the Oxford/Astra Zeneca vaccine. The trial data showed after the first shot, recipients experienced 73% efficacy. While it also requires a second dose, the study found that it could be administered up to 12 weeks apart and still maintain 70% efficacy.
"We recognize that extension to 12 weeks allows us to get the initial vaccine to more people and protect larger parts of the community," said George Findlay the Chief Medical Officer of Brighton and Sussex Hospitals in the U.K..
But for the Pfizer/Biontech and Moderna vaccines, the only two approved by the FDA in the U.S., not all public health officials are convinced they should deviate from the prescribed regimen.
"It's an interesting thought, but the evidence just really isn't there," said Dr. Tyler Evans, the Deputy Public Health Officer in Marin County who is in charge of their vaccine distribution.
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He also argues that planning in advance has been difficult.
"We don't know what's happening two weeks from now in terms of supply because things are constantly changing," he said.
That uncertainty could throw a wrench in the process of extending the window between doses.
"The problem with just vaccinating as many people as possible is you might not get to that second dose in a reasonable time frame," said Evans.
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While a single shot may provide protection for some people, that immunity could wane over time, creating conditions where a vaccinated person may still be able to contract COVID-19. If that starts happening to enough people, he thinks it would erode trust in the vaccine which could be more damaging in the long run.
"That's the most important issue, really having the trust of the community so they will come back for the second dose."