#2 is why it doesn’t seem prudent to just stick it in anyone’s arm when it may not even help control the virus, especially with such few doses available right now.
twitter thread this morning from Bob Wachter, chair of the department of internal medicine at UCSF.
--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)
--The two main changes are the slower-than-expected vaccine rollout and the new variant virus being found in the U.S. Both demand that we turbocharge the process of getting a large chunk of the population at least partly protected. (2/7)
--Here's my back-of-the-envelope math: - Single shot seems to be about 80% protective after a month - 2nd shot adds some efficacy (up to 95% protective), and maybe (tho not yet proven) some durability. - New variant is here, and undoubtedly far more widespread than we know. (3/7)
-- Variant is ~55% more infectious than old one. Even though it's not more deadly, this means that if we engage in same behaviors, many more will get Covid & thus far more will die. UK shows that once here, it spreads fast. - We seem incapable of changing behavior very much. (4/7)
-- As has been widely reported, the roll-out is going far slower than we hoped. - According to most vaccine experts, delaying shot #2 by a few months is unlikely to materially diminish the ultimate effectiveness of two shots (critical point; we should be testing to be sure). (5/7)
--Taken together, if we have vaccine doses to distribute in Jan-Apr, it seems increasingly evident that a strategy of getting as many people (particularly high-risk) their first shot ASAP will save far more lives than sticking with the two shot plan. (6/7)
--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. You? (7/7)