At least a dozen colleges and universities across the U.S. restored their indoor mask mandates this month after Covid cases rose on their campuses. 

Columbia University, Johns Hopkins University and Georgetown University, among others, announced they will again require face coverings in classrooms or certain indoor spaces. Some schools cited the threat of the more contagious omicron BA.2 subvariant, now the dominant strain of the virus in the U.S.

Their moves come as BA.2 fuels a rise in cases nationwide and a divide on whether to again mandate masks to blunt its spread. Policymakers have considered the politically divisive question of whether to require face coverings just weeks after many cities loosened their public health restrictions, offering Americans a sense of normalcy unseen since the pandemic hit more than two years ago.

“The national debate over mask mandates is certainly reflective of both pandemic fatigue and the deep political divides we have in terms of the public health policy related to Covid,” said Neil Maniar, director of Northeastern University’s Master of Public Health in Urban Health Program. 

“It is impossible to disentangle the political aspect from the public health and science-based realities of how we can respond to this pandemic,” he said.

The shift away from pandemic-era rules — and concerns about whether the moves were premature amid rising cases — continued last week after a U.S. district judge struck down a federal mask mandate for planes and other public transit. The Biden administration plans to appeal the decision.

Philadelphia also lifted its indoor mask mandate Friday, just days after becoming the first major U.S. city to reinstate it. Public health officials said the reversal followed a recent decline in Covid cases and hospitalizations in the city. 

The average number of new cases fell to 242 per day as of Thursday, compared with a peak of 377 on April 14. Hospitalizations also fell to 65 on Thursday, down from 82 on April 17, according to a city press release. 

Six schools in Philadelphia responded to the city’s reversal, loosening their tougher mask rules that were reintroduced earlier in the week in line with the mandate. They include Thomas Jefferson, Drexel, Temple, La Salle and St. Joseph’s University. 

The University of Pennsylvania also lifted its mask requirement for indoor public spaces on campus, but still requires masks in classrooms, on campus transit and in health-care settings. 

Maniar said decisions about masks represent a shift toward more local, individualized decision-making when responding to the pandemic. 

“We’re going from this one-size-fits-all approach to much more localized, much more tailored approaches that really respond to what the what the level of Covid is in a certain community, organization or university,” Maniar said. 

“Depending on what is happening in a certain area, reinstating a mask requirement may or may not be warranted as long as it’s done in a way that is responding to the data that is evident at the local level,” he added.

Beyond Philadelphia, changes in Covid infections have forced academic institutions to reconsider their mask policies. Three schools in New York state reinstated their indoor mask mandates. 

The University of Rochester announced earlier this month that it would temporarily puts its indoor mask mandate back in place for all of its campuses and properties. The university said it was responding to a spike in Covid cases that is “straining the capacity” of quarantine and isolation spaces on its campuses. 

“The trending high numbers of positive student COVID cases at the University in recent days make it in everyone’s best interest to take the step of re-masking indoors right now,” the university said in a statement. 

In New York City, Columbia University said earlier this month that students would be required to wear noncloth masks in classrooms for the rest of the spring semester. Columbia cited an uptick in NYC case counts and the university’s test positivity rate. 

Barnard College, a women’s school affiliated with Columbia, also reimposed its mask mandate for certain indoor spaces on April 6 due to a spike in cases since it lifted the rule on March 28. 

The decisions come as cases rise in the largest U.S. city. The seven-day rolling average of daily new cases in NYC was 2,348 on April 18, up from 2,027 a week earlier, according to data from the Centers for Disease Control and Prevention. Cases in the city have since dropped to a seven-day average of 1,565, the data shows.

In New York state, excluding New York City, the overall the seven-day rolling average was 4,029 on April 24, up from 3,631 on April 18 and 2,899 a week earlier, CDC data said. The state’s seven-day test positivity rate also jumped from 3.65% to 8.97% from April 1 to April 22. 

New York state and NYC have not reinstated indoor mask mandates after they lifted them several weeks ago. But the Metropolitan Transportation Authority still requires masks on subways and buses in NYC, despite the Florida judge’s decision to strike down the federal mask mandate on transportation last week. 

New York Gov. Kathy Hochul said in a Twitter post that the transit mask requirement would remain in place in accordance with guidance from the state health department.

In Washington, D.C., Howard University is the latest school to reintroduce mask requirements. Students will have to wear face coverings for all indoor settings and outdoor group settings through the end of its spring semester. The university also went a step further than other schools, announcing it would hold certain undergraduate courses online during the last days of classes and conduct final exams virtually. 

George Washington University also announced earlier this month that it would require masks for all campus facilities. The school noted that the mandate would extend through the rest of its spring semester, exam period and commencement. 

American University also reinstated its indoor mask mandate for all campus buildings and Georgetown announced it would require masks indoors on two of its campuses. Both universities said the mandate would not apply to individuals in private offices or personal residences, or to people actively eating or drinking. 

All four universities in D.C. cited high transmission in the region and significant case increases on their campuses, which are partially driven by BA.2. 

The seven-day rolling average of daily new cases in Washington was 119 on April 18, down from 293 a week earlier, according to CDC data. The district’s seven-day test positivity rate, however, rose from 1.8% to 5.45% from April 1 to 17. The percentage of positive cases has since dropped to 3.89% as of April 22. 

Washington ended its indoor mask mandate in late February and has not reinstated it since. D.C.’s Metro made masks optional on its buses, railways and shared-ride transit service after the Florida judge’s ruling. 

The return of mask mandates at universities goes beyond major cities such as New York and Washington. Schools that reintroduced indoor face covering requirements include the University of Connecticut, Bowdoin University, Rice University and Williams College. Johns Hopkins also said on April 6 it would require masks in classrooms, common areas of residence halls and dining facilities, except when actively eating or drinking. 

Maniar said other universities and local jurisdictions could reinstate their mask mandates in the future, adding that they should base their decisions on Covid indicators in their communities. 

“It’s certainly possible to bring back masks where we’re seeing a rise in the number of cases, a corresponding increase in hospitalizations, and a corresponding increase in the percent positivity,” he said. 

Maniar added: “We just want to avoid a situation where we’re overburdening the healthcare system in a certain community or area. So if we start to see a rise in those indicators, then I can see that triggering a reinstatement of mask requirements in some settings and certainly in university settings.”