Metro said it will cut weekday bus service to Saturday levels beginning Monday as it faces a growing number of employees sickened by the coronavirus or exposed to it.

The schedule, which includes extra buses on some routes, is about 75 percent of normal, the agency said.

The transit system already had cut bus service on some routes because of driver shortages. Metro General Manager Paul J. Wiedefeld said the switch to the Saturday schedule, a move made by the agency’s pandemic task force, would provide passengers with more reliable service.

“Metro employees live in some of the neighborhoods hardest hit by the pandemic and are exposed to the surge in the region and throughout the nation,” Wiedefeld said in a statement. “It’s important that the taskforce take steps to make Metro operationally sound to meet the needs of our customers.”

Rail service is not affected but is already operating at reduced levels as Metro seeks to safely get defective 7000-series rail cars into service.

Transit agencies around the country have been struggling with the spike in coronavirus cases attributed to the omicron variant. High caseloads among employees have also led airlines and Amtrak to scale back service.

The Centers for Disease Control and Prevention cut in half the number of days people who test positive for the virus should stay home, in part to keep essential parts of the economy moving. But Metro’s cuts are another example of how the unprecedented wave of cases is stretching front-line services thin at a time when, unlike the early weeks of the pandemic, fewer people are staying home from work and school and are relying on transit service.

Raymond Jackson, president of the local chapter of the Amalgamated Transit Union, the largest guild for Metro workers, said the changes announced Tuesday were a positive step but that Metro should do more to protect workers, like returning to backdoor bus boarding.

In conjunction with the service cuts, Metro announced measures designed to offer workers additional protection from the virus. Call center operators will work remotely, and bus drivers will be allowed to pass by passengers waiting at stops who are not wearing masks. Federal rules require masks on public transportation through March 18.

Jackson said that could lead to masked passengers also being passed by, but drivers have to keep themselves and other riders safe.

“Have enough respect for me and my family to put a mask on,” he said. “If you give me the opportunity to leave you behind at the bus stop because you don’t have a mask on, then I applaud the authority for making that decision.”

The transit agency is also taking steps to stiffen its vaccine-or-test process. Beginning Jan. 16, employees who don’t follow the protocols will face suspension and could be fired. At the end of the month, Metro said it will require employees to verify they have received booster shots.

New York’s transit system has been particularly hard hit, with officials suspending service on some subway lines last week. The surge in caseloads arrived as agencies already were struggling to attract workers, sometimes offering hefty bonuses to recruits.

At Metro, Jackson said morale was at a low.

“My members have been out on the front lines of this virus now for two years,” he said. “We come to work like we’re supposed to. We come to work scared.”