A push in Ontario to get residents to switch their old red and white health cards to the new green photo version is catching some by surprise.

Pat Harrison was one of them.

She moved 15 years ago and notices telling her to get the new card weren't forwarded. She had no idea her coverage had been suspended since 2006.

When her car was rear-ended this month in an accident she was rushed to a Brampton hospital. She was told her old card was invalid and she'd have to pay.

"No coverage, no doctors, no treatment," Harrison said she was told. "Unless you want to pay for it."

Harrison left and went home. She later found out she had a concussion.

"I was horrified actually. What would have happened if I was very seriously injured," she said.

Nearly 3 million old cards out there

Recently, ServiceOntario launched a new push to get people to give up their old red and white health cards.

A ServiceOntario spokesperson said four out of five Ontarians now have the new OHIP card, which was introduced in 1995.

That still leaves nearly three million older cards out there.

Nicole Ottaviano got a letter in the mail saying she had 30 days to get a new card.

"If something were to happen and I didn't have a chance to come in within 30 days, I don't know what would happen," Ottaviano told CBC News.

The province has been trying to eliminate the old cards that don't have an expiry date, to cut down on health fraud.

"At this point there's no specific deadline," said Anne-Marie Flanagan of Ontario's Ministry of Government and Consumer Sevices.

"But, we are encouraging people to get the new photo health cards. The government will be phasing out the red and white health card in the future," she said.