However, if face mask use is reduced by 50%, a vaccine that is only 50% effective (weak vaccine) would require coverage of 55-94% to suppress the epidemic in these states [CA, NY, TX, FL]. A vaccine that is 80% effective (moderate vaccine) would only require 32-57% coverage to suppress the epidemic. In contrast, if face mask usage stops completely, a weak vaccine would not suppress the epidemic, and further major outbreaks would occur. A moderate vaccine with coverage of 48-78% or a strong vaccine (100% effective) with coverage of 33-58% would be required to suppress the epidemic.
That is from a new paper by Mingwang Shen, et.al., via Alan Goldhammer.
As for the European lockdowns currently under way, I do not know which choices those nations should be making. The British one, which I know the most about, seems far too strict to me. No matter what your exact point of view, surely there is something to David Conn’s comment:
Government gone from spending £500m paying people to eat out, to closing all the restaurants, in 2 months.
In any case, if those nations had continued (or in some cases initiated) widespread mask use, they would be facing much, much better trade-offs today.