I see three main lessons from Britain’s recent rise in cases: One, vaccines are still the most effective way, by far, to defeat this terrible pandemic. Nothing matters more than the speed at which shots go into arms — in Britain, in the U.S. and especially in poorer countries, where vaccination rates are still low. Two, behavior restrictions can still play a role in the interim. If hospitalizations or deaths in Britain rise over the next two weeks, there will be a strong argument for pushing back the full reopening of activities. And that has obvious implications for the U.S., too. Restricting indoor activities for unvaccinated people is particularly important. Three, caseloads are no longer as important a measure as they used to be. Before the vaccines were available, more cases inevitably meant more hospitalizations and deaths. Now, the connection is more uncertain. As a recent Times story put it, paraphrasing British scientists, “upticks in new infections are tolerable so long as the vast majority do not lead to serious illness or death.”