ABC News this week reported that Vermont, which has the highest vaccination rate in the country, is seeing a surge in new cases. Breakthrough cases among vaccinated residents were up 31% in a week.

The state health commissioner said there was no single answer to why. The Delta variant is hardy and ever on the prowl for new people to infect. People are gathering again. And we are seeing waning immunity among those who were vaccinated early in the year.

I think people are coming to terms with the realization that the Covid vaccine is similar to the flu shot. That shot offers a moderate to high degree of protection against influenza. You have to get it every year. It doesn’t eliminate the chance you’ll get the flu; it lowers it.

Nobody calls it the flu vaccination, though technically that’s what it is. It’s the flu shot. And what we call things matters because it reflect our understanding and expectations. People and institutions are already signaling without saying that they understand the limits of the Covid shot. At the theater in New York they closely, carefully check everyone’s vaccinated cards and phone apps, and then underscore that everyone must wear a mask. If you have a roomful of people you know are vaccinated, and vaccination means they are immune from Covid, masks would be irrelevant. At two recent shows, one on Broadway, the other Off-, they reminded you of the rules charmingly. An usher would tap her nose once, softly, while showing the crinkled eyes of a smile when he or she saw you accidentally-on-purpose let the mask fall below your nose. At a recent wedding the hosts required two vaccinations plus proof of a Covid test within three days. It was a prudent and realistic request, but you wouldn’t do the latter if you had full confidence in the former. Which none of us at this point do.