Not so easy: With whooping cough on the rise in Europe, getting a national picture in Canada is complicated

Europe has reported high levels of whooping cough in the past few months, but risk in Canada depends on where in the country you find yourself—with Quebec seeing unusually large numbers.A recent editorial in the Lancet raised alarm bells about rising pertussis rates in the U.K. noting they rose steadily from December 2023 to early June 2024. Several other European countries have also seen worrying increases, both in places with declining vaccination rates, and even in some places where rates are high.The editorial stated that so far in 2024, the Czech Republic had the “highest number of pertussis cases for more than 60 years, and this has also been seen in the USA.”It also stated that “Reports indicate that whooping cough outbreaks are surging across Europe, Asia, and parts of the United States, including Northern California, marking the largest uptick since 2012, with cases rising sharply since December.”In Canada, pertussis is a nationally reportable disease with surveillance conducted by the provinces and territories who report cases to the Public Health Agency of Canada (PHAC) through the Canadian Notifiable Disease Surveillance System (CNDSS).” But data from the CNDSS comes with a serious lag and are currently only available until 2021, with data up to 2022 set to be available later this summer, and 2023 data available next year according to PHAC sources. When asked for a current, national look at pertussis, a Health Canada spokesperson told the Medical Post in an email “For more recent data, please contact the provinces and territories directly.” According to PHAC, Canada sees between 1,000 and 3,000 people fall ill from pertussis each year. “Pertussis is a cyclical disease, and as such, there are years in Canada and across the world where there are more cases reported than others. Pertussis activity generally increases every two to five years, with cases in Canada ranging from 500 to 4,500 annually. Increased pertussis activity this year is not unexpected as it follows a period of low incidence during the years of the COVID-19 pandemic.”Unlike flu or measles which have weekly monitoring reports, pertussis is not tracked the same way, nationally. However, epidemiologist and director of the Centre for Vaccine Preventable Diseases, Shelly Bolotin speculated on the reason for the difference. In general, “pertussis activity in Canada is region specific. At any point in time activity can vary greatly between jurisdictions, so it can be tricky to make national decisions based on provincial or territorial data.”Pertussis can also be considered as being seasonal—but not as seasonal as flu (flu activity is sometimes regional as well). However, Canada does submit pertussis data to the World health Organization WHO, with the most current data available from 2023, when Canada reported 1,433 cases of pertussis.Pertussis is endemic in much of Canada, usually characterized by low level activity and cyclical increases generally occur about every two to six years. Increases can be influenced by factors such as population immunity, vaccination coverage, or changes in the pathogen, among others.The Medical Post queried all of Canada’s provincial and territory public health agencies, and this is the scenario for pertussis as of the end of July (from those provinces that responded).ALBERTAAlberta Health reported 347 confirmed cases of pertussis in 2024, but currently, there are no outbreaks. About 60% of those cases were in not immunized or under-immunized individuals where immunization status was known.“Pertussis cases increased in 2023, peaking in September, but monthly case numbers in 2024 have declined since then.”BRITISH COLUMBIAAccording to the BC Centre for Disease Control, in relation to the disease’s three-to-five-year cyclical peaks, such peaks in B.C. occurred 2012, 2015 and 2016. As of June 27, 2024, 72 confirmed cases of pertussis were reported, but there were no community outbreaks by then.While 72 cases is higher than the number of confirmed cases during the same January through June period of other COVID-19 pandemic years, it remains lower than any other year of the past decade. A review of cases through early April 2024 showed most were reported among people who were not vaccinated. In comparison, January through June tallies of confirmed cases ranged from 111 in 2020, to 166 in 2018, and 433 in 2016. It noted that pertussis rates typically show an increase through late spring and summer in B.C..MANITOBAThe province continues to see ongoing cases, but there are about 50% fewer cases than 2023. NEW BRUNSWICKThe incidence rate for pertussis in 2024 from Jan. 1 to July 13, is 5.8 cases per 100,000 population.The average rate for that same time period in the previous five years, 2019 to 2023, was 4.2 cases per 100,000 population. But an outbreak of pertussis was declared on the Acadian Peninsula on June 27, with 36 cases. A total of 48 cases have been reported in the province so far this year.NEWFOUNDLAND and LABRADORHealth and Community Services of Newfoundland and Labrador is reporting higher rates of pertussis compared to previous years due to an ongoing outbreak. The Eastern Urban and Rural Zones of Newfoundland and Labrador Health Services are experiencing the highest number of cases. By mid-July of this year, over 150 cases have been reported in 2024.This is higher than usual numbers. From 2014 to 2023, an average of 3.6 pertussis cases were reported each year making this is an unexpected surge driven by an ongoing outbreak.Newfoundland and Labrador has high vaccination coverage with coverage rates above 90% for the childhood pertussis vaccine. But the statement noted that vaccine immunity against pertussis can wane over time.NORTHWEST TERRITORIESThis year, as of July 23 2024, zero cases of pertussis were reported to the Office of the Chief Public Health Officer. The last reported case in NWT was in 2021. Annual numbers of reported cases are generally quite small, with peaks in activity that resulted in outbreaks in 2015, 2019, and 2020. Overall, between 2014 and 2023, 102 cases of confirmed pertussis were reported in Northwest Territories. As for vaccine coverage, since 2019, annual three-dose coverage in two-year olds has ranged from about 81% to 87% and sat at about 81.2% in 2023NOVA SCOTIADr. Ryan Sommers, the province’s senior medical director of Population and Public Health, stated that in 2024 the province saw two cases, and that at the moment there were no regions of concern.“With the recent rise in cases elsewhere in Canada and in some of our neighbouring provinces, we have been anticipating an increase. Our biggest concern right now would be the increase of pertussis activity in New Brunswick and Newfoundland,” he said.NUNAVUTNunavut’s Department of Health reported that an outbreak has been ongoing in the Kivallique region since March of this year, totaling 32 cases this year, according to a news report. The most recent case was reported near the end of July. ONTARIOAn Public Health Ontario’s (PHO) July Monthly Infectious Disease Report, 206 cases were reported by the end of May 2024. Generally, the monthly provincial case counts in February, March and April of 2024 were below a pre-pandemic five-year average, 2015 to 2019.“Cases in May were above the pre-pandemic average, but not above a threshold considered to be significantly elevated.” Generally, there is increased pertussis activity across the province rather than in a single region.“The last cyclical increase of pertussis activity in Ontario occurred several years ago, therefore an increase in pertussis at this time is not unexpected, particularly following a sharp decline during the COVID-19 pandemic,” PHO said.QUEBECAn alert with no date was issued on the provincial public health agency’s website which stated that pertussis is on the rise in the province. According to the province’s ministry of health, there have been 8,851 reported cases of pertussis from January 2024 through July 27. A total of 3,511 cases occurred in July. A CBC news report stated that the overall numbers this year, are over 33 times the number of cases compared to this time last year. SASKATCHEWANThe Saskatchewan Ministry of Health reported that the province has seen a slight increase in the number of pertussis cases. At the end of June this year, the number of pertussis cases rose from the normal one to four per month, up to six confirmed cases.

Not so easy: With whooping cough on the rise in Europe, getting a national picture in Canada is complicated

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