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Since the beginning of March, Harvard has gradually scaled down its on-campus Covid-19 restrictions — a shift from the cautious approach the school took to managing the virus over the last two years.

On March 1, faculty began removing their masks in lecture halls. Thirteen days later, the school’s mask mandate was lifted in most indoor spaces. Two weeks after that, social gatherings were allowed to resume in undergraduate residence halls.

But one key requirement remains: testing.

When Harvard announced in February that it would allow professors to begin teaching unmasked, University Health Services Director Giang T. Nguyen wrote that “regular surveillance testing will remain an important part of our campus protocols.”

“It will continue to help us understand the presence of COVID-19 in our community and inform any subsequent steps we may take in response to the data,” he wrote.

But some experts say testing requirements, too, could soon be on the way out.

Undergraduates are currently required to take a Covid test once per week. But some public health experts say phasing out asymptomatic Covid testing requirements is reasonable for schools that require full vaccination, like Harvard.

In an interview last week, Harvard President Lawrence S. Bacow said the University will eventually stop requiring asymptomatic affiliates to test for Covid — but he stopped short of specifying when.

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A total of 430 Harvard affiliates tested positive for Covid-19 last week as the school saw a large uptick in cases among graduate students and staff, according to the University’s Covid-19 Testing Dashboard. While recent case counts remain lower than those in January, when the Omicron variant first emerged, the school has seen a surge over the past week.

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Boston University medical school professor Elissa M. Schechter-Perkins said “now is a very reasonable time” to stop required asymptomatic surveillance testing, as long as schools have high vaccination rates.

“We really have developed so many tools to fight this illness that it makes sense that we are starting, at this point, to peel back some of our mitigation layers — and asymptomatic screening is one of them,” she said.

Around 98 percent of Harvard students and 97 percent of school employees are vaccinated.

Thomas N. Denny, chief operating officer of the Duke Human Vaccine Institute, said asymptomatic surveillance tests have become less useful with the emergence of the fast-spreading Omicron variant, which has a significantly shorter incubation period compared to previous variants.

“With Omicron, the numbers just don’t work,” he said. “You can’t get the swab, get the test result, and implement an isolation period, for the majority of the cases, in the timeline that matters.”

Philip J. Landrigan, a Boston College public health professor and epidemiologist, said a school’s decision to end surveillance testing should depend on case rates in the surrounding area.

In Cambridge, where 76 percent of residents are fully vaccinated, the positivity rate over the past two weeks was 2.3 percent. Cases have risen in recent weeks — but nowhere near the city’s peak in January.

Boston College and Northeastern University have both ended testing mandates for vaccinated affiliates.

Bacow said Harvard will rely on the University Coronavirus Advisory Group — which includes medicine, public health, and public policy experts — to make a decision on when to end mandatory asymptomatic testing.

“They are advisory, but I have never rejected their advice,” he said. “The day will come, I’m certain, when they will say, ‘We should no longer test,’ and I probably will accept their advice when that day comes. It hasn’t come yet.”

—Staff writer Cara J. Chang can be reached at cara.chang@thecrimson.com. Follow her on Twitter @CaraChang20.

—Staff writer Isabella B. Cho can be reached at isabella.cho@thecrimson.com. Follow her on Twitter @izbcho.