WASHINGTON - A surge in coronavirus infections among Amtrak employees has created a staffing shortage and forced the passenger railroad to reduce service beginning Monday on the busy Washington-to-Boston corridor. 

While about 97% of Amtrak employees are fully vaccinated, several hundred workers - including conductors, engineers and mechanics - have been hit by infections or exposures as caseloads of the highly transmissible omicron variant remain elevated nationwide, railroad officials said.

"These COVID-related absences, when combined with the general skilled workforce shortage Amtrak and other transportation companies are facing, have reduced our ability to consistently deliver our current schedules and impacted the pace of hiring and training efforts," Amtrak said in a statement.

Service cuts next week in the Northeast Corridor will affect 8% of weekly departures. The cutbacks will continue through March 27, Amtrak said.

Amtrak on Tuesday suspended 6% of state-supported routes and is cutting back some long-distance trains starting Monday. Service will go from daily to five times a week on the Southwest Chief, California Zephyr, Empire Builder, Coast Starlight, Crescent, Texas Eagle, Capitol Limited, Lake Shore Limited and City of New Orleans routes. The Silver Meteor between New York and Miami will be suspended, and riders can use the Silver Star or Palmetto routes instead, Amtrak said.

The cutbacks on America's passenger railroad service are the latest in a growing list of transportation disruptions across the nation amid weather- and omicron-related challenges. Airlines in recent weeks have canceled thousands of flights while public transit agencies are reducing bus operations, citing staff shortages because of the fast-spreading variant.

Amtrak said it is working to fill vacant positions and train new employees to avoid staffing issues resulting from unplanned absences.

The company said the service reductions should have "minimal impacts" on ridership as the railroad has experienced a 25% drop in demand because of omicron amid its typical winter travel slowdown.

Still, the service cuts have frustrated travelers, many of whom received notices of canceled trains in recent days, leaving them to reschedule departures.

Jim Mathews, president and CEO of the Rail Passengers Association said these service reductions are "all probably inevitable" considering the turmoil wreaked by omicron.

"Amtrak is doing the best it can with a bad hand," said Mathews, who in the past has criticized Amtrak service cuts. "The temporary cutbacks will be in the reservation system and scheduled, rather than being an unpleasant surprise. And Amtrak is promising that those who are already booked will either get rebooked or refunded."

Passengers whose trains are canceled are being notified and given the choice to rebook same-day travel alternatives. Those without a same-day option, chiefly on long-distance routes, will be offered travel within one day of the original departure date, Amtrak said.

Amtrak last month had warned about potential service reductions as a result of a vaccine mandate. The company, however, suspended the vaccine requirement for its roughly 17,000 workers and averted the termination of about 500 people - and planned service cuts - this month. Railroad employees who aren't vaccinated are allowed to opt for weekly testing.

Reverting the vaccination policy eased a worsening staffing problem at Amtrak. It is down 1,500 workers since the start of the pandemic and is struggling to hire amid a national shortage. The company said in its statement that it is faced with riding out the omicron wave, which it expects will "continue to impact parts of Amtrak's network and the availability of our fleet in the near term."