Tufts Medical Center hit a symbolic milestone in its main Boston hospital in Chinatown last week: For the first time in more than three years in the pandemic they had zero COVID-19 patients.

It lasted for just one day, but it had a big impact, said Dr. Shira Doron, chief infection control officer for the Tufts Medicine Health System, who became a familiar voice in local news reports during the pandemic’s early days.

She said administrators at Tufts got emotional when they heard that news.

“[They had] tears in their eyes,” Doron said. “I mean, just think about where we were. The onslaught right from the first patient, which was March 21, 2020, ramping up so fast, opening another ICU and another ICU and another ICU, trying to find ventilators, no PPE, no hand sanitizer. I mean, hideous. It was just like, where else are you going to hit us, and how high is this going to go? We didn't know. And to have zero? Pretty awesome.”

COVID-19 public health emergencies on both the federal and state levels came to an end Thursday, bringing both practical and symbolic changes to life in the pandemic. For instance, mandatory masking is gone in many health care settings.

But COVID still circulates. In the last week of April, there were 14 confirmed and two probable deaths attributed to the virus. As the public’s perception of the virus has changed, so has the way public health professionals view it.

Doron said now she'll be treating COVID-19 like other respiratory viruses, which can still be dangerous, but not as an unpredictably deadly agent from those days in the spring of 2020 that led to long-term shutdowns of schools and businesses.

One major change has been in immunity: Three and a half years after the virus’ emergence, most people have some immunity from a vaccine, a prior infection or a combination of the two.

Researchers are still studying how long immunity lasts and what it means for infection levels. But the death rate has dropped significantly, thanks to immunity levels, other mitigations like masking and better treatments for infected people at high risk.

“We know that it was probably on the order of 10 to 100 times more deadly than flu,” said Stephen Kissler, an immunology and infectious diseases researcher at the Harvard T.H. Chan School of Public Health. “Now, it's probably on the order of like, 2 to 4 times, maybe. And that's a huge difference, right? That is a huge drop.”

That significant drop has changed the way scientists think about the virus, he said.

“I think it is a big driver of this change in the way that we talk about the pandemic as now ending this emergency of international concern,” Kissler said.

Many people are back to some semblance of normal life. Still, the pandemic has left a lasting mark: More than 22,000 people in Massachusetts have died; Others have dealt with grieving lost loved ones, with the stress and trauma of the pandemic, and with lasting long COVID-19 symptoms.

The fault lines of disparity that were revealed and deepened by the pandemic are not over. The damage done in some vulnerable communities continues, said Boston Medical Center infectious disease physician Dr. Cassandra Pierre, associate medical director, associate hospital epidemiologist and medical director of public health programs.

"COVID-19 has probably weakened the health of Black and brown communities already."
-Dr. Cassandra Pierre, Boston Medical Center

Life expectancy went down disproportionately for Massachusetts residents of color during the pandemic compared with white residents, Pierre said.

“I would say COVID-19 has probably weakened the health of Black and brown communities already,” Pierre said. “And so how much worse is it going to get once we pull back these resources, pull back these mitigation methods and measures, and have no idea what's actually happening in the communities that have been most structurally vulnerable? And what does that look like when we enter the next pandemic?”

Even with ongoing concerns, Pierre said she thinks it is a good moment to end the public health emergency — but we shouldn't let down our guard, especially when it comes to people who are medically or socially vulnerable. She also pointed out that Black and brown people in the vulnerable communities that her hospital serves are still more at risk for getting COVID-19, more at risk for getting a severe case if they are infected and more at risk for Long Covid.

Pierre said she'll be watching what may be the best metric: COVID-19 wastewater levels, and particularly the neighborhood-level data for the more vulnerable communities that BMC serves: Roxbury, Mattapan, the South End, Hyde Park and southeast parts of Boston. She said they'll be trying to adjust to any worrying and changing conditions as they crop up, even without an emergency declaration to back them up.