After more than a year of pandemic restrictions, many Americans are leaving their masks behind, making summer travel plans and joyously reuniting with family and friends. As more are vaccinated and new infections plummet, there is a sense that the worst of the pandemic is over in the United States.

But for people like Michele Preissler, 60, the worst has just begun.

Ms. Preissler lost her husband to Covid-19 in late May, just as many restrictions were being lifted and life, for many, was starting to look more like normal. Customers were going without masks last week at the Walmart near her home in Pasadena, Md., where she was shopping for items for her husband’s funeral.

“Everybody is saying, ‘Oh, it’s fine,’” said Ms. Preissler, who said her husband, Darryl Preissler, 63, loved to hunt, camp and go crabbing with his grandson, and was not vaccinated when he caught the virus at a wedding in early April. “I’m just thinking to myself, ‘If you only knew what I just went through.’”

With half of Americans protected with at least one dose of a vaccine, the virus outlook in this country is the best it has been at any point in the pandemic. New cases, hospitalizations and deaths are lower than they have been in many months, and even the most cautious health officials are celebrating the country’s progress. Fully vaccinated people, who are at low risk of catching and spreading the virus, have been told they can take off their masks and return to many regular activities, with the support of top scientists.