Significant increase in whooping cough cases in Quebec in recent weeks

Measles, TB, whooping cough are back, but why? Dr. Donald Vinh explains why we're hearing shout measles, TB and other diseases we'd thought were long gone.

More than 900 cases of whooping cough have been reported across Quebec since the start of 2024, including some 200 cases in recent weeks. The Eastern Townships and Chaudière-Appalaches regions are by far the most affected.

Also known as pertussis, whooping cough is a highly contagious disease whose main symptoms are coughing fits, low-grade fever, runny nose and red, watery eyes.

Ear infection and pneumonia are possible complications of whooping cough, and the risk is higher in babies under one year of age. As of April 30, a total of 19 confirmed cases and three probable cases have occurred in children under one year of age in Quebec.

The Quebec government website noted that children under three months of age suffer the most serious complications. They account for nearly half of all hospitalizations, the majority of intensive care admissions and almost all deaths due to pertussis (although deaths remain rare).

In an e-mail to The Canadian Press, the province's health ministry noted that pertussis is a cyclical endemic disease, with peaks of activity every two to five years. The last peak in Quebec was in 2019, when 1,269 cases were reported.

Health measures linked to the COVID-19 pandemic significantly reduced whooping cough cases between 2020 and 2021. But with more social contact since 2022, the ministry anticipates a resurgence of the disease.

In the Chaudière-Appalaches and Eastern townships regions, incidence rates are up compared with the same period in 2023 and for pre-pandemic years.

Since the start of this year, 469 cases have been reported in the Eastern Townships, including 53 cases in the first two weeks of May. In the Chaudière-Appalaches region, 182 cases have been reported since the start of the year, including 84 cases from April 28 to May 11.

Montérégie has recorded 50 cases since the start of the year; Laurentians 41 cases; Bas-Saint-Laurent 42 cases; Quebec City region 43 cases and Lanaudière 20 cases. These regions all saw around ten new cases in 14 days at the beginning of May.

Vaccination is the best way to protect against pertussis, said the provincial government. The pertussis vaccine can be administered as early as two months of age, and is a combination vaccine.

Pregnant women can also receive the vaccine. Babies under three months of age are the most vulnerable to severe pertussis infections, and much less so if the mother was vaccinated during pregnancy.

According to the Government of Canada, pertussis vaccination coverage should reach 95 per cent to establish herd immunity. In 2021, in Quebec, vaccination coverage among the population aged two and under was 89 per cent, according to the most recent data from the Quebec public health institute (INSPQ).

For the time being, the health ministry has no plans for a large-scale pertussis vaccination campaign in schools.

--

This report by The Canadian Press was first published in French on May 21, 2024. The Canadian Press health content receives funding through a partnership with the Canadian Medical Association. The Canadian Press is solely responsible for editorial choices.