As travel picks up and delays continue at Canada's busiest airport, along with the emergence of new Omicron subvariants, some are saying the situation won't ease up any time soon.

"I say pack your bags, pack your patience," travel expert Jim Byers told CTV News Channel on Sunday.

"Bring a podcast to listen to, bring a book, have a snooze, set the alarm on your iPhone for an hour or so and just have a little bit of a rest or go for a walk, because it is inevitable."

Travellers have expressed frustrations for weeks over long delays, cancelled flights and winding lineups at Toronto Pearson International Airport.

Nearly half a million passengers were held up after arriving on international flights at Pearson in May.

Some have pointed to staffing levels at customs and immigration desks, as well as COVID-19 border measures, combined with a surge in passenger traffic as contributing to the problem.

Byers says travellers should arrive at Pearson about three hours in advance just to be safe.

While there are some legitimate issues occurring globally, such as supply chain constraints, he says nearly everyone in the travel industry predicted this "pent-up demand."

The federal government says it has hired nearly 900 Canadian Air Transport Security Authority screening officers across Canada to help address wait times.

It also has suspended mandatory random COVID-19 testing at all airports as of June 11. The suspension will run until the end of the month before moving off-site.

Starting Monday, domestic and outbound international travellers are no longer required to show proof of vaccination against COVID-19. Foreign nationals coming to Canada must still be vaccinated in order to enter.

Dr. Christopher Labos, a Montreal-based cardiologist and epidemiologist, meanwhile, cautioned Canadians to be mindful of the risks when travelling.

"I mean, there are many places in Europe where COVID is increasing. There are many places in the U.S. where COVID is increasing. So there are definitely surges in play right now," he told CTV News Channel on Sunday.

Some experts say a rise in Omicron subvariants BA.4 and BA.5 could lead to an increase in cases in Canada.

Labos says care should be taken depending on where you go and what you do.

He also cautioned travellers to check their travel insurance policies for any exclusions based on whether a person gets COVID-19.

"If you're going to go somewhere and sit on the beach and not really interact with other people, then your risk of getting COVID is probably pretty low," Labos said.

"But if you're going to be going to places, and going to nightclubs, and going to a lot of indoor settings and coming into contact with a lot of people, there is a certain risk there."

With files from CTV News and The Canadian Press