The sole provider of blood to more than 45 Bay Area hospitals is asking for 1,000 more people to donate each week for the foreseeable future to stem a blood shortage, officials with supplier Vitalant said this week.

Vitalant has less than two days of Type O blood left. Type O blood is the type most needed and transfused and critical in emergency situations.

Type O+ is the most common blood type and O- is the universal blood type, which can be used when a doctor does not know the blood type of the patient.

Even though the need for Type O is critical, blood of all types is needed, Vitalant spokesman Kevin Adler said.

Vitalant tries to always keep a four-day supply of blood on hand.

Behind the decline in donations, Vitalant officials said, may be the return to a more normal lifestyle. Not enough people are making donations or keeping appointments to make them, according to Vitalant.

The rate at which donors are not keeping their scheduled appointments hit an annual high recently, Vitalant officials said.

People are also being asked to give platelets, which are cells that help blood clot. Vitalant is experiencing a critical shortage of platelets, which must be transfused in seven days after a donation, Adler said. About 50 percent of platelets are given to cancer patients receiving treatment.

People can donate blood regardless of their COVID-19 vaccine status, but Vitalant does require a mask to be worn. Potential donors can check their eligibility and for a place to donate on the organization’s website.

Nonprofit Vitalant serves about 900 hospitals nationwide.