By CBS3 Staff

PHILADELPHIA (CBS) — This flu season is on track to be one of the worst in recent history, now that high flu activity is taking a toll on the country’s blood supply. The month of January is already a low donation month, but experts say the flu is making it worse.

Some donation centers around the country only have a three-day supply of certain blood types.

“We also can’t pass on any blood donated from somebody that is sick because that could be a compromised immune system,” Angela Monteagle said.

Blood centers are looking for donors with all different types of blood.

But right now, there is a critical shortage of O-negative blood, also known as the universal donor.