"Right now, most have about a 4-day supply," said MacPherson. "We consider a 2- to 3-day supply to be safe until we absolutely have to go out and get more."
MacPherson said when the supply gets down to about 2 days worth of blood, centers will start previous donors to encourage them to donate. After that, centers will reach out to community organizations and ask them to hold blood drives and if there's still a need, will try to get blood from other centers that may have a surplus.
The media is often a last resort, because publicity tends to attract prior donors, who will then be unable to give blood for a while. Centers, he said, hope to reach out to new donors.
"The fact that the Red Cross has reached out to the media means they have a very urgent need," he said.
The New York Blood Center, which provides blood to more than 200 hospitals and serves more than 20 million people, says despite the area's brutal winter, supplies are adequate.
Rob Purvis, the vice president of the New York Blood Center, says one advantage regional blood centers have over national organizations like the American Red Cross is a stronger connection with donors.
"Our donors are connected with our hospitals in a way," he said. "When you're distributing on a national basis sometimes, that connection doesn't happen as freely."
Another issue that inhibits blood supply is that only about 30 percent of the population is eligible to donate blood, and of those, only about 5 percent actually do.
"The low eligibility is mostly related to illness-related exclusions and travel to areas where there are concerns about infections," said Sacher.
Most donors are also older adults, which is why Sacher said Hoxworth Blood Center, the center he directs, often reaches out to students at the center's affiliated University of Cincinnati.
These new donors are exactly the ones Brian Boyle wants to encourage to get out and donate. He works with the Red Cross to get the message out.
"By giving just a little bit of your time, you can give somebody like me a lifetime," he said.