Metro will require employees to be vaccinated against the coronavirus or submit to weekly tests as the transit agency looks to push its workforce vaccination rate higher while trying to boost rider confidence in the system.

The policy goes into effect on Sept. 7 and will make Metro one of a handful of large transit agencies to draw a hard line on employee immunization. The agency instituted the mandate after its 12,000-person workforce fell short of a vaccination goal set by Metroleadership earlier this month.

Metro General Manager Paul J. Wiedefeld said 45 percent of employees are fully vaccinated, according to an internal memo sent to employees Tuesday announcing the policy. The mandate is the latest push in the Washington region to boost uptake of vaccine doses as the delta variant of the coronavirus has sent caseloads to their highest levels in months.

“We need to do better to protect our workforce and our customers from Covid infection, especially given the prevalence of the Delta variant in our region,” Wiedefeld wrote.

Early this month, Wiedefeld raised the possibility of regular screenings of unvaccinated employees if the workforce didn’t reach a 70 percent benchmark. At the time, 40 percent of employees had reported being vaccinated.

In comparison, 60 percent of Maryland residents and 56 percent of District and Virginia residents are fully vaccinated.

The Metropolitan Transportation Authority of New York will start a similar vaccination policy on Labor Day, while the New Orleans Regional Transit Authority also has required its workforce to get vaccinated with few exceptions.

Transit ridership continues to lag across the country and at Metro, where the rail system averaged 138,000 daily trips last week, about 12,000 fewer than a month ago and less than a quarter of average daily ridership in 2019. Metrobus is operating about two-thirds as many daily trips compared with two years ago. The bus system averaged 196,000 daily trips last week, an increase of about 13,000 from the same period last month.

While coronavirus fears are not a primary reason most riders are staying away, according to an agency survey of SmarTrip cardholders, Wiedefeld has repeatedly said that Metro’s focus is making sure people feel safe.

About 13 percent of the agency’s workforce is confirmed to have contracted the coronavirus. Most have returned to work; six have died.

Scott Bogren, executive director of the Community Transportation Association of America, said transit leaders nationwide are split on how to handle vaccination requirements. Some would welcome a federal mandate, which would make it easier to impose the requirement. Others say such a policy would drive workers away.

Latisa Holmes, a vaccinated Metrobus operator who recovered from a serious case of the coronavirus last year, said some co-workers she tries to persuade to get the shot are scared of the unknown.

“A lot of employees are hesitant,” she said. “They don’t want to get vaccinated at all. I think it’s personal.”

Metro has offered three days of paid time off after a first shot and another two days after a second shot. Holmes said the inconvenience of obtaining weekly tests might provide more effective motivation for co-workers.

Wiedefeld said Metro workers will not be allowed to work without uploading proof of negative coronavirus test results every week — or proof of vaccination — to an internal employee database. Employees can ask to be exempted for medical or religious reasons.

Unvaccinated workers will be responsible for their testing, Wiedefeld said, and expenses won’t be reimbursed.

“The expense and scheduling of this test is your responsibility,” Wiedefeld said. “Also, please understand that failure to comply will result in immediate ineligibility to work and progressive discipline.”

Metro’s largest union, Amalgamated Transit Union Local 689, said in a statement that vaccination is “the most effective way to save lives during the pandemic,” but union officials declined to say whether they support the testing requirement.

The union urged Metro to pay for testing for those who choose not to get immunized. ATU Local 689 President Raymond Jackson said in a statement the union will continue to negotiate with Metro on the policy.

Jackson also said Metro should be consistent on its enforcement of coronavirus safety protocols, saying the agency doesn’t adequately ensure compliance with a federal mask mandate for public transit. That mandate was extended Tuesday into January 2022.

Metro spokeswoman Sherri Ly said the agency emphasizes “compliance without conflict,” and does not ask employees to confront riders who aren’t covering their faces. Train and bus operators, as well as Metro Transit Police officers, are asked to pass out masks or direct passengers to kiosks stocked with face coverings.

Nonunion workers and contractors also must comply with the policy, Wiedefeld said, and new hires will be required to show proof of vaccination to start work. Mike Funderburk, a parts clerk at the Cinder Bed Road bus garage in Fairfax County operated by a Metro contractor, said his supervisors have encouraged workers to get vaccinated but haven’t required it.

Wiedefeld said Metro’s mandatory testing requirement is similar to policies for District employees and Maryland and Virginia state government workers.

It “will help strengthen our collective defensives against the virus and its variants,” Wiedefeld said. “This is a deadly disease, and we have to work together to fight it for everyone’s sake.”