For most of 2020, many of us thought that once fully vaccinated — which initially meant two doses of the Pfizer or Moderna vaccines, or one dose of Johnson & Johnson — our lives would return to pre-pandemic normal. Masks would come off, schools and workplaces would reopen, and we’d declare victory over covid. But then the delta variant arrived, and hospitals began once again filling with covid patients.

That’s why no one is “moving the goal posts” by calling for boosters and more (and better) masks. Most experts predicted early on that herd immunity could be reached at somewhere between 80 and 90 percent of the population vaccinated. Some suggested it could be as low as 70 percent. But we’ve suffered from both poor luck and poor effort.

A year after covid vaccinations become available in the United States, our vaccination rate sits at a dismal 62 percent — far from even the most optimistic estimates of herd immunity. And variants such as delta and omicron — both highly contagious and prone to cause breakthrough infections — push the threshold up further still, forcing scientists to amend the definition of “fully vaccinated.”