Latest news with #CarolineColijn
CBC
18-03-2025
- Health
- CBC
Concern grows over low measles vaccination rates in parts of B.C.
Social Sharing Scientists are raising the alarm over low measles vaccination rates in parts of B.C. as concern grows over outbreaks in Ontario and Texas. Health officials in Ontario say there have been 350 cases of the virus in the province since late October — with 173 of those infections reported within the last several weeks — and in late February, an unvaccinated Texas child lost their life in the first U.S. measles death since 2015. The measles, mumps and rubella vaccine — which is safe and highly effective at preventing infection and severe cases — is recommended for children between 12 and 15 months old for the first shot, with the second coming between the ages of four and six. However, the Okanagan and Kootenay-Boundary regions of B.C. showed less than two-thirds of seven-year-olds were up to date with their measles shots in 2023, the latest year on record, well below the recommended 95 per cent rate to achieve herd immunity. Across B.C., as a whole, the percentage of seven-year-olds who were up to date with their shots has been dropping steadily for over a decade, and the province as a whole saw only 72 per cent coverage in 2023. The province has thus far reported four travel-related cases of the virus this year, all of which are related to air travel to Southeast Asia. Scientists say it's more imperative than ever that people check the vaccination status of their children, especially as measles is incredibly contagious and has high hospitalization rates for those who aren't vaccinated. "I think we do have areas and school districts where there are enough unprotected children that measles could take off if it gets introduced here," said Caroline Colijn, a Canada 150 Research Chair in mathematics at Simon Fraser University. Last month, Colijn and her co-authors published a modelling study on measles to see what happens when the respiratory illness is introduced to a community, and what level of vaccination coverage or previous immunity from infection is needed to prevent outbreaks. The SFU scientist says that measles is so infectious that if there's an exposure in a room, anyone who's not immunized will go home with measles — and symptoms may not appear for seven to 10 days afterwards, making contact tracing difficult. BCCDC says rate likely higher Jia Hu, the interim medical director for immunization programs at the B.C. Centre for Disease Control, says that while B.C.'s measles vaccination uptake looks low among children, actual rates are likely a bit higher given some residents may have just moved to the province and others are not registered in the provincial immunization registry. Still, he acknowledges that rates are lower than where public health officials want them to be for the preventable disease — which was considered eradicated in Canada in 1998. WATCH | Health authority urges British Columbians to check measles vaccinations: Health authority says to check children's vaccine status, amid rising measles cases 11 hours ago Duration 2:01 Vancouver Coastal Health is reminding parents to check their children's vaccine status. It comes with measles on the rise globally and outbreaks in Ontario and Texas. As Michelle Ghoussoub reports public health officials are warning vaccination rates in B.C. are worryingly low. Hu says that the pandemic disrupted many childhood vaccine schedules, which could explain the downturn in vaccination rates. He added the data shows that many seven-year-olds in B.C. were eligible for their second measles shot at the peak of the pandemic. WATCH | Travel-related measles cases confirmed in B.C.: More travel-related measles cases confirmed in B.C.'s Lower Mainland 10 days ago Duration 1:53 "I also think, more worryingly, that there probably has been a decline in people's willingness to get measles-containing vaccine or any vaccine for that matter, right?" he said. "In the aftermath of the pandemic, we've seen, you know, a lot more, vaccine hesitancy." Hu says that officials had a responsibility to increase the measles vaccination uptake, by reaching out to community leaders in places where people could be vaccine hesitant. "I think the combination of information and vaccine availability would really help increase uptake for other communities where I think vaccine hesitancy is more entrenched," he said. Hu says that vaccines are the best way to prevent a disease that has high hospitalization rates — with the doctor saying that at least 10 per cent of Canadian cases have led to hospitalization. Colijn says that Canadians have perhaps collectively forgotten how bad measles is, and says the disease can cause brain swelling and immune system damage in children who are not protected. "We don't want to have to rediscover how bad these are and then rediscover how to prevent them," she said of childhood diseases. "We've already been down that road."
CBC
08-03-2025
- Health
- CBC
A play-by-play of how measles outbreaks can spiral out of control
This story is part of CBC Health's Second Opinion, a weekly analysis of health and medical science news emailed to subscribers on Saturday mornings. If you haven't subscribed yet, you can do that by clicking here. Measles infections are ticking up and up across multiple provinces, with more cases already this year than all of 2024. Local public health alerts of new cases come with detailed descriptions of the person's whereabouts before they were diagnosed. We're told which hours and minutes a passenger spent in airports in Vancouver, Toronto, and Fredericton, how long other patients were in an emergency department north of Toronto or family health clinic in eastern Ontario, and just how long someone visited a sit-down chain restaurant in Quebec's Laurentians. The announcements raise a couple questions: Why do measles cases seem to be slipping through health-care professionals' fingers — or even going unrecognized by patients or their families? And, why give such detailed information on where a person went? The answers lie in how incredibly contagious the measles virus is, coupled with the cornerstone role vaccination plays in stopping spread. "What those announcements are trying to do is really make people aware so that they can protect ... others around them and watch out for their own symptoms," said Caroline Colijn, an epidemiologist who holds a Canada 150 Research Chair at Simon Fraser University in Burnaby, B.C. Last month, Colijn and her co-authors published a modelling study on measles to see what happens when the respiratory illness is introduced to a community, and what level of vaccination coverage or previous immunity from infection is needed to prevent outbreaks. "Because measles is so incredibly infectious, it can spread rapidly, even if most people in a community, 80 per cent, for example, are immunized," Colijn said. "The usual threshold is that you would want 95 per cent of the people in a community to either have been vaccinated or to have had previous measles exposure." However, vaccination rates have been falling in Canada and elsewhere, and the early symptoms of measles may go unrecognized — adding to the risk of spread. Hardy and highly contagious virus Measles spreads through the air when someone coughs, sneezes or talks, so even spending a few minutes in that same airspace can pose an infection risk to someone who isn't vaccinated, such as an infant who is too young to receive the shots. A single infected person can infect 90 per cent of their close contacts, if they're unvaccinated. The virus that causes measles is also hardy, lingering on surfaces for two hours after an infected individual leaves. That's why case counts can spiral quickly. A single person, on average, infects 12 to 18 others who are susceptible to measles. That means if one patient infects 15 others, who each infects 15 others, you end up with 225 cases. If each of those people infects 15 others, you're at 3,375 cases, and so on. Another wrinkle is that the symptoms of measles overlap with more common respiratory illnesses, including influenza, which is also circulating in Canada now. When someone who is vulnerable to the measles virus is exposed, they may show the "3 C" landmarks of the infection about 10 days later: Cough. Coryza, or inflammation of nasal mucous membranes, which leads to a runny nose. Conjunctivitis or redness of the eyes. "These are very similar to things we would see with the flu," said Dr. Mark Kirchhof, president-elect of the Canadian Dermatology Association and an associate professor at the University of Ottawa. "It can be easily confused." When people unknowingly infected with measles chalk up the symptoms to influenza, a cold or COVID-19, especially early on, they may interact with family, go to school, work and other public places and expose others who haven't been vaccinated, Kirchhof said. That's why local public health officials and physicians encourage people to call ahead before coming to a clinic if the person is unvaccinated and showing cold symptoms. That way, staff can cordon off an area to prevent further spread of measles. Measles rash appears on the face first When the Canadian Dermatology Association observed an uptick in measles in 2023, the group started raising awareness about the measles rash, other symptoms and who is vulnerable to complications. Kirchhof said dermatologists can lend a hand at helping colleagues to recognize measles, which many doctors have only read about in textbooks and never seen in real life. Two or three days after the symptoms of cough, a runny nose and conjunctivitis arise in someone infected with measles, a cluster of white dots will often appear on the inside of the cheeks near the molars. These are known as Koplik spots after the pediatrician who first identified the pattern's link to measles infection. WATCH | Mapping the spread of measles in Canada in 2025: Once declared eradicated, measles is surging in parts of Canada 10 days ago Duration 2:05 Measles was declared eradicated in Canada in 1998, but with vaccination rates dropping, new cases are surging; 95 people have been infected in just the first two months of this year, compared to 147 for all of 2024. Then, a few days after the Koplik spots appear, a characteristic rash starts on the face and spreads downwards to the neck, legs, arms and feet. "The rash itself is red dots," Kirchhof said. "Some of them you can feel, and some of them might be flat. Sometimes they can cluster together to form larger red areas over the body, and in some patients it can be somewhat itchy." Depending on skin tone, the brightness of the rash may vary, doctors say. It's the delay between exposure and when measles symptoms erupt, followed by the time lag between types of symptoms that explains why someone who eventually seeks treatment may pass through airports, schools, grocery stores and hospitals before being diagnosed. Initially, measles affects the respiratory tract, and common complications include ear infections. But measles can also lead to high hospitalization rates. It is estimated nearly one to three of every 1,000 children who become infected will die from complications, such as pneumonia and a swelling of the brain called encephalitis. There is no specific treatment for measles infection, which needs to run its course. Countering fall in childhood immunization rates The best prevention, public health officials in Canada and internationally stress, is vaccination. But, amid declining vaccination rates, some people on the internet or on social media may promote treatments that lack evidence, Kirchhof said, such as vitamins or supplements that maintain general health, though don't specifically treat measles. In contrast, federal figures reflect the power of high vaccination rates to curb outbreaks. Before measles, mumps and rubella (MMR) vaccinations started to roll out in Canada in the 1970s, tens of thousands of cases occurred each year. More recently, falling vaccination rates in children in Canada and international travel reintroducing the virus have also contributed to outbreaks, scientists say. Dr. Sarah Khan, an infectious diseases specialist and associate professor at McMaster University, was part of the team who cared for an unvaccinated child who died of measles last year in Hamilton. "It's devastating when you have to manage a vaccine-preventable disease that results in a fatality," Khan said. Given the timing and other factors, Khan said managing even a single case of measles can be a challenge. Doctors say those at highest risk of exposure, such as an infant or someone who is pregnant, may benefit from a medicine called immune globulin to reduce the risk of developing measles. "It really does require early recognition, early notification and a lot of coordination for all of the exposed individuals," Khan said.
