Whooping cough cases are surging in Canada. What’s going on?

Quebec has seen the biggest spike in cases, with more than 11,600 reported so far this year, up from the annual average of 562 cases between 2015 and 2019.

Whooping cough cases continue to increase in multiple provinces, but as kids head back to school, doctors and health-care professionals say there could be multiple factors behind the spike.

The bacterial infection, also known as pertussis, typically shows up seven to 10 days after being infected and its symptoms usually start with a mild fever, runny nose and a cough. The Public Health Agency of Canada notes that can lead to fits of coughing that can last two to eight weeks, or even up to 10 weeks, according to the U.S. Centers for Disease Control and Prevention.

Quebec is seeing the biggest jump, surpassing pre-pandemic levels with more than 11,000 cases as of last week, while New Brunswick declared an outbreak on Aug. 22 with 141 cases — exceeding the five-year average.

Dr. Isaac Bogoch, infectious diseases specialist at Toronto General Hospital, said vaccination access could be a factor.

According to Bogoch, there are some groups of people who may not have access to vaccinations through a family doctor or public health clinic; others may be choosing not to vaccinate, and there could also be people who missed a dose of a vaccine due to COVID-19 disruptions to health care.

The World Health Organization noted in a 2021 report that 3.5 million children worldwide missed their first dose of the vaccine.

But it’s not just a lack of vaccination that may be behind the surge.

Bogoch and other experts said there are a few possible factors at play.