MONTREAL -- While countries around the world are considering issuing “immunity passports” to people who have recovered from COVID-19, researchers warn there is little evidence the virus can't be caught a second time.

Cedric Yansouni, an infectious disease specialist at the McGill University Health Centre, warned that even with ramped testing for the virus and antibodies, reopening the economy could come with risks.

“I would caution viewers to regard with great suspicion the results of an antibody test,” he said. “Neither I, nor anyone else in the field, would be able to tell you with a great degree of certainty what it means.”

A popular conception of viruses is that once a person has recovered from one, they are then immune, but political and scientific authorities say a cautious approach is needed and that much is still unknown about COVID-19.

“I think any such discussions or decisions need to be based on very strong and very clear scientific evidence,” said Prime Minister Justin Trudeau.

According to the World Health Organization, a positive test for COVID-19 antibodies doesn't necessarily mean a person is totally immune to the virus.

“Right now we have no evidence that the use of a serologic test will show that an individual is immune or is protected from reinfection,” said WHO infectious disease specialist Maria Van Kerkhove.

Yansouni said that even if some immunity is granted, it may be temoprary and that there's a question as to whether tests are accurate enough to identify the specific strain of the COVID-19 coronavirus a person had.

“The bigger concern is whether the currently available antibody test will cross-react, i.e. Give a common result among people who haven't had COVID but have had the coronavirus that causes the common cold every year,” he said.

According to Health Canada, 20 applications have been issued for tests, including antibody tests.

“Health Canada has not approved a single antibody detection kit for the coronavirus yet,” said McGill University science communicator Jonathan Jarry. “We also have to remember that bad information is worse than no information.”