U.S. health officials worked to redistribute flu vaccine to the neediest as worried Americans took matters into their own hands, heading across borders to Canada and Mexico to get shots on Friday.

Despite daily pleas for patience and updates on new shipments and new sources of vaccine from federal health officials, people continued to flock to flu shot clinics, and lining up at grocery stores, pharmacies and doctors offices to get immunized.

The estimated vaccine supply is up to about 61 million doses, about 60 percent of the 100 million doses that were planned for this year’s flu season before vaccine maker Chiron Corp. unexpectedly lost its license after contamination was found at its British plant.

Nearly 48 million doses were lost.

Centers for Disease Control and Prevention officials turned to the other major influenza vaccine supplier for the U.S. market, Aventis-Pasteur. The company opened some distribution records to CDC and squeezed out a few million more doses.

MedImmune, maker of a nasal vaccine, found another 1 million doses for a total of 3 million on Thursday.

“Nearly 3.2 million influenza vaccine doses were shipped this week to health providers serving high priority groups,” the CDC said in a statement issued late on Friday.

The federal government has no power to seize vaccine but has been working to persuade distributors to redirect supplies to those most likely to die or become seriously ill from flu - the elderly, chronically ill, babies and pregnant women.

The CDC said more than 5 million doses had been shipped to state public health departments, Veterans Administration hospitals, nursing homes, acute care hospitals, the Vaccines for Children program, and doctors serving high-risk groups.

Still, Americans flooded pharmacies and clinics with calls, went onto Internet forums looking for vaccines, and even crossed borders looking for shots.

Two major pharmacy chains in the Mexican border city of Reynosa said they were struggling to find vaccines.

“Right now the demand is coming not from Mexico but from the United States, and supplies are very scarce on the market,” said Jose Manuel Hernandez, a branch manager of the 18-strong Benavides chain of pharmacies in Reynosa.

Canadian officials said Americans seeking flu shots have been showing up at various clinics near the border and at Vancouver International Airport, which has a health clinic.

“We’re well supplied,” said Viviana Zanocco, spokeswoman for the Vancouver Coastal Health Authority.

Cruise operator Victoria Clipper in Seattle offered a day-trip return ride to Victoria, 75 miles northeast of Seattle on Canada’s Vancouver Island, that for $105 includes a dose of flu vaccine.

“We have been bombarded by phone calls,” said Darrell Bryan, Victoria Clipper’s general manager.

After newspapers reported that members of Congress could get shots their constituents often could not, the attending physician there said he was donating 3,000 doses to Washington city medical officials.

And federal officials said they would help fight reported price gouging.

Health and Human Services Secretary Tommy Thompson said HHS and the U.S. Department of Justice filed a friend of the court brief on Friday in support of Florida’s suit against Meds-Stat, accused of selling vials of flu vaccine to a Kansas City, Kansas, pharmacy for $900. Vials typically sell for $63 to $85.

“We need the entire nation to work together to ensure that the flu vaccine gets to those who need it most, and our companies need to be good corporate citizens to accomplish that goal,” Thompson said.