On Sunday, the number of coronavirus vaccinations administered in Massachusetts rose by 72,047 to 3,904,179, state officials said.The number of people fully vaccinated — with either two shots of the Moderna or Pfizer vaccines or one shot of the Johnson & Johnson — rose to 1,478,520, the Department of Public Health said.Updates on coronavirus cases, deaths, and other metrics were not released Sunday. That data will be included in Monday’s report, according to the state COVID-19 dashboard.On Saturday, the state reported 2,263 new confirmed coronavirus cases, bringing the state’s total to 605,055. The department also reported 30 new confirmed coronavirus deaths Saturday, bringing the state’s total to 16,938.The coronavirus case counts are steadily rising as 90 percent of school districts in Massachusetts prepare to send elementary school students back to full-time, in-person learning on Monday.Last week, COVID-19 cases among public school students and staff members reached their highest weekly total since the beginning of the academic year.Despite the record-breaking report — 801 new coronavirus cases among students and 244 among school staffers for the week that ended April 3 — state officials and public health experts have said the figures aren’t a signal that schools are unsafe.They cited varying factors, including a rise in virus cases among young people and the number of children and staff members inside schools recently hitting the highest levels since classrooms closed in March 2020.CDC officials have said in-person school is safe for children, as long as precautions are taken, including maintaining 3 feet of distance between students and universal mask wearing.Dr. Davidson Hamer, an infectious disease expert at the Boston University schools of Public Health and Medicine, was mindful of the continued disruption to students’ education, but said the decision to allow children to return to in-person classes was “a difficult call.”“The timing is really not optimal because of the recent rise in cases,” he said. “But on the other hand, this has been planned for a while.”If schools make a good effort to sanitize spaces, enforce social distancing, and ensure mask use, the risk of transmission can be reduced, Hamer said. Ideally, routine screenings should be in place to catch outbreaks, he said.Nevertheless, Hamer expressed concern about returning students to class while cases rise, adding that he suspects the increase in recent COVID-19 cases is being driven in part by the B.1.1.7 variant first identified in the United Kingdom.“I think three weeks ago I would have felt better about it,” he said.Some districts, including Boston and Worcester, have received waivers from the state to delay the return to in-person learning. All elementary schools are expected to be fully in person by May 3, according to state education officials.The return to in-person learning has been complicated in some communities by a shortage in school bus drivers.In Lynn, Superintendent Patrick Tutwiler said Saturday that the district had to suspend school bus service temporarily because its transportation vendor does not have enough drivers. The service suspension affects 680 special-education students who require transportation, he said.“I know how important transportation is and it is heartbreaking that we cannot provide it for some of our neediest students,” Tutwiler said in an e-mail. “However, this issue is a temporary one and we are leveraging every resource to move as quickly as possible to resolve it.”The district’s vendor, NRT Bus Inc., now has 18 drivers in Lynn, compared to more than 40 drivers in a typical year, Tutwiler said.In a statement, the company said it has provided all transportation requested by the district since September and has been “working diligently” to rehire drivers and other personnel to serve Lynn and other communities since state education officials announced plans to resume in-person learning this month.“There is no greater priority for NRT than transporting our student passengers to school safely and we will continue to work with districts to ensure that every child who needs a ride receives one,” the statement said.Lynn Public Schools are devising a plan to accommodate students who require transportation, but the details haven’t been finalized, Tutwiler said. Families of students with special needs who require transportation are eligible for mileage reimbursement, he said.Jared Nicholson, a member of the Lynn School Committee, said the bus driver shortage is an equity issue.“Drivers have found other work in districts that were able to come back earlier,” he said. “It’s another example of the pandemic pushing us to rethink how we value the workers that are truly essential to the basic services that we expect and our families deserve.”Tom Hamilton, executive director of the School Transportation Association of Massachusetts, said there are about 1,200 fewer school bus drivers on the job since the pandemic abruptly sent students home in March 2020.Many school bus drivers found new positions after their employers stopped receiving payments from some school systems and laid off workers, he said Saturday.“The drivers are just like anybody else. They need to put food on the table,” Hamilton said.In Springfield, school leaders warned families on Friday that a bus driver shortage could cause transportation disruptions on Monday.On Saturday, Springfield Superintendent Daniel Warwick said bus routes were adjusted and the district was no longer bracing for widespread transportation delays.“We think we have it all set for Monday morning,” he said.A spokesman for First Student Inc., the transportation vendor for Springfield Public Schools, said recruiting school bus drivers was challenging even before the pandemic because low unemployment rates created a lot of competition for workers.Chris Kemper, the spokesman, said First Student is offering a $1,500 signing bonus to new drivers in Springfield as part of its recruiting efforts.“This is a very unique opportunity,” he said. “Some of our folks will tell us it’s the toughest job you’ll ever love. They do it for the kids.”Globe correspondent Abigail Feldman contributed to this report.Laura Crimaldi can be reached at [email protected] Follow her on Twitter @lauracrimaldi.