Whooping cough cases are on the rise in Canada, with some provinces reporting sharp increases compared to pre-pandemic averages.

More than 11,670 cases have been reported in Quebec so far this year, a significant jump from the annual average of 562 cases between 2015 and 2019.

The majority of whooping cough patients are between the ages of 10 and 14, a spokesperson for Quebec鈥檚 health ministry said in an email to The Canadian Press.

The last peak of whooping cough activity in the province was in 2019, when 1,269 cases were reported, the email said.

As of June, Ontario has seen 470 whooping cough cases, compared to the five-year average of 98, a provincial dashboard shows.

Toronto has reported 99 cases so far this year, while Ottawa has seen 76 鈥� more than double the pre-pandemic annual averages recorded in those cities.

These figures come on the heels of a whooping cough outbreak declared last week in New Brunswick with 141 cases reported so far, exceeding the five-year average of 34 cases per year.

The highly contagious, vaccine-preventable disease also known as pertussis is on the rise across Canada and can be very serious in young children, Canada鈥檚 chief public health officer Dr. Theresa Tam said last week.

Whooping cough is a cyclical disease that increases every two to five or six years, public health officials say.

鈥淚t would appear that we鈥檙e currently in one of those cyclical increases,鈥� said Dr. Allison Chris, an associate medical officer of health at Toronto Public Health.

The illness marked by a persistent cough begins with cold-like symptoms and evolves over several weeks to include coughing spells that often end with a 鈥渨hoop鈥� sound when an infected person is catching their breath.

New Brunswick鈥檚 acting chief medical officer of health says the province hadn鈥檛 seen a whooping cough outbreak in more than 10 years.

鈥淚 guess you could say we were certainly overdue for an increase in cases,鈥� Dr. Yves L茅ger said in an interview Tuesday.

L茅ger said he expects the current case count to get worse before tapering off, given an increase in public awareness surrounding the provincial outbreak and the reporting that will likely come with it.

Vaccines that protect children against whooping cough are part of Canada鈥檚 routine immunization program, beginning at two months old. Primary immunization requires four doses, followed by booster shots later in childhood and adolescence.

A dose of acellular pertussis-containing vaccine is also recommended for adults and during pregnancy.

Chris said setbacks in routine vaccine coverage since the COVID-19 pandemic could point to waning pertussis immunity.

The COVID vaccine hesitancy observed during the pandemic could have also rubbed off on routine vaccine uptake, Dr. Anna Banerji, a pediatric infectious diseases specialist in Toronto, said in an interview.

Another challenge is that 鈥渆ven in fully vaccinated people, after a period of time, the immunity can wane,鈥� Banerji said Tuesday.

A rise in whooping cough cases has also been reported in the United States and elsewhere, prompting the Pan American Health Organization to issue an alert in July encouraging countries to ramp up their surveillance and vaccination coverage.