(CNN) Shipping giants FedEx and UPS may have to make alternative plans to ship the new Covid-19 vaccine in areas that are expected to be affected by a major winter storm this week.
The first public deliveries of the vaccine made by Pfizer and BioNTech took place Monday in every state plus Washington DC, and Puerto Rico. Officials expect to ship 2.9 million doses in the coming days.
The storm is expected to develop on Tuesday and impact the eastern United States on Wednesday and early Thursday. People from southwestern Virginia to Massachusetts are under a winter storm watch. The heaviest snow totals are expected from Pennsylvania to southern New England, including New York City, where more than a foot of snow is possible.
Travel could be very difficult or even impossible in some of the areas that the storm will hit, the National Weather Service said.
FedEx spokeswoman Shannon Davis wrote in an email that as of Monday, the company didn't expect any "significant impact" to service.
"We have a team of 15 meteorologists monitoring conditions 24/7, and we have contingency plans in place should we see any severe weather," she said.
The company continues to monitor the forecast, she added.
A UPS spokesman said the company recently opened a health care command center at Worldport, its global air hub in Louisville, Kentucky.
"The command center watches every package of COVID-19 vaccines from origin to destination, and can step in with contingency plans should it appear that a package may be delayed," said UPS spokesman Matthew O'Connor.
Like FedEx, UPS has a full-time team of meteorologists.
"We develop contingency plans based weather forecasts and local conditions, enabling our employees to safely deliver what matters most," he said.
The company has hired 100,000 seasonal employees and is well-staffed for vaccine and holiday shipments, O'Connor said.
Army Gen. Gustave Perna, the chief operating officer of Operation Warp Speed, told reporters Monday that the operation had plans for many different issues, with the worst case scenario being an accident of a delivery vehicle or aircraft. Bad weather falls in the middle of the spectrum of problems, he said.
Some doses will be held in a "safety stock" should there be an issue.
"My responsibility to deliver safe and effective vaccines means get ahead of that problem, so we're constantly thinking where do we need to, where we can possibly be vulnerable and how can we mitigate it," he said.
The winter snowstorm will hit parts of the mid-Atlantic into New England beginning Wednesday, when shippers are scheduled to make 66 deliveries nationwide. Later in the week, other vaccines will be shipped in Pfizer's distribution boxes requiring dry ice.
Heavy snow is expected near and north of the Interstate 95 corridor from Washington to Boston. New York City could get as much as 14 inches, according to forecasts.
There are winter storm watches in parts of Connecticut, Delaware, Maryland, Massachusetts, New Jersey, New York, North Carolina, Pennsylvania, Virginia and West Virginia.
Blustery wind conditions will also be a concern, with some areas, especially along the coast, coming close to blizzard conditions. Sustained winds of 25 to 35 mph are possible, with gusts as high as 45 mph at times.