Ottawa health officials are trying to ensure they have "covered the bases" by warning almost 7,000 people who had procedures done at a medical facility over a 10-year period that they may have been exposed to infections like HIV, says an expert in infection control.

Dr. Michael Gardam, the director of infection prevention and control for Toronto's University Health Network, said it's hard to talk about the specifics of the infection risk announced Saturday, given so few details have been released.

'There isn't any smoking gun here'— Dr. Michael Gardam, University Health Network

"If it’s a minor lapse, the good news is that these viruses are typically very easily killed by pretty routine measures. So even if there were some minor misses here and there, the chances of anybody getting infected from this would be very, very minimal," Gardam said in an interview with CBC Newsnet on Sunday.

"If it’s a major lapse, then it’s another story but, obviously, we’re not going to know until somebody actually comes forward and tells us exactly what happened."

Dr. Isra Levy, Ottawa's officer of medical health said Saturday the city's public health department has been investigating an unnamed non-hospital facility for the past several months because of unspecified "lapses in infection control" which may have led to some 6,800 people being exposed to Hepatitis B, Hepatitis C and HIV.

Dr. Isra Levy says the chances of anyone being infected are 'very low.' CBC

The chances that someone could have been infected with Hepatitis B is less than one in a million, Levy stressed. In the case of Hepatitis C, those odds drop to less than one in 50 million and are less than one in three billion for HIV, he said.

The lapse was caught in June during a spot check by the Ontario College of Physicians and Surgeons. Only one doctor was involved, Levy said.

Lapses in infection control can go unnoticed for a long time until a facility is audited by a regulatory body, Gardam said.

When asked why public health is sending warnings to so many patients, Gardam said officials have yet to find anyone who has been infected.

"So this is them making sure that they have covered the bases and letting people know that they may have been exposed. The good news is there isn't any smoking gun here," Gardam said.

Those who are affected by the advisory will get a letter on Monday telling them exactly what happened and how they can be tested.

The procedure was stopped at the private clinic in question in June. The investigation has started since then, but the complete list of those who may have been exposed wasn't drawn up until Thursday.

A call centre response unit will be up and running by Tuesday to answer patients' questions. Levy said more detailed information won't be released until the affected patients get their letters.