A medical spokesperson is downplaying the risk to the public after 19 vials of HIV-infected blood were stolen from the locked freezer of a downtown Vancouver hospital.

The blood samples were being stored in a locked freezer on the sixth floor of the facility's virology lab when they were stolen sometime between Saturday and Monday morning.

Dr. Akber Mithani, vice president of medical affairs at St. Paul's Hospital, sought to reassure the public that the only way to infect someone is to introduce it into the blood stream.

"As long as the vials are sealed, they pose no danger to the public," Mithani said, appearing on CTV Newsnet.

"It's not like an airborne disease so that if you're standing next to it or if you handle the vial, which is sealed, that you're actually going to get the HIV," Mithani said.

While HIV-infected blood can remain infectious 72 hours after the vials thaw, Mithani said the virus's strength dissipates as time passes.

"By 72 hours, really there is no risk with respect to the public," he said.

The samples, which were awaiting testing, are labelled with the patients' names, identification number and the letters "HIV VL."

St. Paul's Hospital spokesperson Shaheen Shivji said this was the first time HIV-positive blood had been stolen from the hospital.

"We've not had such a break-in in any of the freezers before. They are locked and the area is part of the regular security personnel patrols," Shivji told CTV Vancouver on Tuesday.

She said the hospital's security video tapes would be checked and security measures were being stepped up.

"If people do come across a vial and they suspect it could be a vial that was stolen, we ask them to call police right away," Shivji said.

Mithani is baffled as to why someone would steal the vials.

"It is strange. We haven't had any incidents like this one ever before in St. Paul's," he told The Canadian Press.

"We could come up with all kinds of theories around it but it would all just be speculation," he said. "I have no idea why somebody would want this."

Mithani said putting a person's name on the test vial is required by regulation.

Each patient is being contacted to let them know what has happened.

Marcie Summers, who works with HIV positive patients at the Positive Women's Network, is troubled with the breach of patient confidentiality.

"There is so much stigma attached to this disease that people who are HIV-positive stand to lose their families, their homes, their jobs if their status is disclosed without their permission," Summers told CTV Vancouver, "So it's very serious."

St. Paul's is home to the B.C. Centre for Excellence in HIV/AIDS.

With a report from CTV Vancouver's Janet Dirks