With vaccines in wide circulation and case numbers plummeting, July 4, 2021, was going to be our “Independence from COVID Day.” Well, we all know what happened next.

The delta variant swept across the country and quickly became the dominant form of the virus during a summer of high caseloads, a stressed health care system and far too many deaths.

Then, around Thanksgiving, the omicron variant arrived and drove a fourth wave of COVID, again resulting in illness and death.

This year’s Memorial Day should be the occasion for us to remember how quickly things changed for the worse last year, and what we still need to do to keep safe

In Maine, we are seeing some good news. Hospitalizations, the most important metric for tracking serious illness, are trending down from its recent peak.

The rate of transmission, however, is still a cause for concern. The state finished the month of May averaging 420 new cases a day, down from a seven-day average of nearly 4,000 in late February. But 420 cases a day is four times the average of new cases on this date last year, just before the delta variant hit.

Thanks to vaccines, which protect people from serious disease, and antiviral treatments, which are available to people at risk of serious illness, more cases don’t necessarily mean more hospitalizations. But it stands to reason that the more people there are walking around with infections, the more likely we are to face a new surge.

There are other ways that managing the virus will be different this year than it was in the last two summers. There are no mask mandates or limits on gatherings, but we have much more information about where the virus is spreading than we had in the past. That knowledge should help, if we’re smart.

According to the federal Centers for Disease Control and Prevention, only one of Maine’s 16 counties, Sagadahoc, is in the low-risk zone. The rest of the state falls in either the moderate-risk zone, where people at high risk of serious illness are advised to wear masks and take other precautions, or the high-risk zone, where people are advised to wear masks in all indoor public spaces.

These designations change with rising and falling levels of cases, and everyone should pay attention to what level of protection they should consider.

Regardless of the local situation, everyone should get vaccinated and boosted. The rest of the guidance hasn’t changed much over the last two years:

If you feel sick, stay home. If you test positive, isolate. If you are exposed, quarantine.

Don’t forget to wash your hands frequently and avoid crowds.

And if you start hearing that the pandemic might be behind us, remember last year’s Memorial Day and how quickly things can go bad.