In the nick of time, North American Vaccine Inc. said yesterday, a savior came through with a bank guarantee that will replenish the company's depleted coffers and allow it to continue operating.

North American, of Columbia, would not identify the guarantor. The arrangement, which provides for an immediate $5 million cash infusion, is part of a broader agreement under which North American will negotiate exclusively with the mystery backer for a possible sale of the company.

In addition to the $5 million infusion, the agreement provides for up to $25 million in additional operating funds, roughly enough to carry North American Vaccine to the middle of next year, when the company expects to begin receiving substantial revenue under a deal to sell meningitis vaccine to the British government.

Without the new arrangement, North American, a company with a promising "pipeline" of new vaccines but not much revenue, could have run out of cash as early as this month. The financing agreement means North American will soon be operating at the sufferance of a benefactor it declines to identify to its shareholders, a fact that angered some of them yesterday.

Investors were also less than thrilled to learn they are likely to receive little or no premium over current share prices if the buyout goes through. The company said a buyout would occur at a "per share purchase price that is in line with the recent trading price of the company's common stock."

The stock closed yesterday at $5.37 1/2, up slightly for the day but down dramatically from the $29.75 high at which the shares traded in 1997.

North American has been plagued by production problems on its one U.S.-approved product, a childhood vaccine called Certiva. Some investors who have long held positions in the stock blamed the company's board and management for letting North American Vaccine run so low on cash that it had little room to negotiate a better sales price.

"These guys should be ashamed for getting themselves into this position," said Mike Delaney, a Chicago investor who has a "substantial" part of his net worth tied up in North American shares and stands to lose money. "The buyer has them over a barrel."

Company executives in Columbia put out a vaguely worded statement yesterday and would say little else about the new financial arrangement. The statement did make it clear that the potential buyer is not Biochem Pharma Inc., a Canadian company that has invested heavily in North American Vaccine.

A North American spokesman referred inquiries to Neil Flanzraich, a pharmaceutical executive in Miami who is chairman of North American's board. He failed to return two telephone calls seeking comment. Aides said he was busy in meetings.

For weeks, speculation in online chat rooms and among company employees has held that North American will be sold to Baxter International Inc. of Deerfield, Ill., best known as a maker of medical devices. Baxter, which has been growing through acquisitions, has a small vaccine unit in Austria and is known to want a higher profile in the vaccine business.

"They definitely have an interest in the area," said Daniel T. Lemaitre, a Merrill Lynch analyst who follows Baxter. He added that he had no specific knowledge of a buyout plan involving North American Vaccine.

Deborah Spak, a spokeswoman for Baxter, said the company is subject to constant rumors about its buyout intentions. "It is our policy not to comment on such rumors," she said.