More vaccinations needed to curb Alberta measles cases: infectious diseases expert

CTV News

29-05-2025

University of Calgary Microbiology, Immunology & Infectious Diseases Professor Craig Jenne speaks with Alberta Primetime host Michael Higgins about the rising measles case numbers in the province
This interview has been edited for clarity and length.
Michael Higgins: The last time we spoke was in late March. At the time it was below the 50-case mark. Now it's more than 10 times that.
What's to be made of the rate of growth or progression and what might that say about how it's spreading?
Craig Jenne: I think what we've seen in the last two months is the transition from these localized exposures, so within family, households or single businesses, to now community level spread, and unfortunately measles is the most contagious virus we deal with.
Now that it does have a toehold in the community, we can continue to expect these 100+ case weeks for the foreseeable future.
MH: The province has released some stats on vaccination rates, telling CTV News more than 47,000 vaccines were administered province wide between March 16 and May 11. A 57 per cent increase over the same period last year.
How much of an impact might that have on dynamics?
CJ: Ultimately, vaccination is the single best tool we have to bring this in, but we have a long ways to go. There are a number of regions in the province where vaccine rates are below 50 per cent, and we know from past experience that to control measles, we need the community to have 95 per cent of the individuals vaccinated.
So 45,000 doses, good start, but when we're talking about literally having to vaccinate millions of people, we still have a long ways to go.
MH: Does there come a point where the case count peaks or levels off, or should Albertans just expect it to keep growing and growing and growing?
CJ: I think unfortunately for the near future, they're going to continue to grow. We base this largely on what we see in other places of the world.
In Ontario, they've been dealing with measles since early fall of last year, and if we look at Alberta's numbers on a per capita basis, recognizing we're smaller than Ontario, we've now eclipsed them in a matter of under three months.
So the cases grow quite rapidly here, and as a result, it's going to require significant effort to bring that back under control.
MH: How worrisome is that from a health standpoint?
CJ: It's quite worrisome. We do know that, typically, we can tolerate a few measles cases every year. But as those numbers go up, again, previous outbreaks have shown us one to three children out of every 1,000 infections will likely lose their lives.
So as the numbers grow, the risk of those severe outcomes, unfortunately, grows proportionally.
MH: There had been site specific exposure advisories in the South Zone but since last Friday, that became a standing advisory.
If it is that the exposure source isn't known, what comes of the challenge of tracking and attempting to contain it?
CJ: Right now it's nearly impossible to track them in the South Zone. We are seeing measles acquisition in many different public places, and as a result, these health advisories are simply stating that there's a risk of measles pretty much anywhere in the community.
We have seen cases from the B.C. border, through the province, and the south, to the Saskatchewan border. We do know it's there, we do know it's circulating in the community, and really the only personal defense when we don't have these localized exposures is immunization.
MH: The South Zone, south of Calgary, includes cities like Lethbridge and Medicine Hat.
If you don't live there, but you do plan on visiting, or maybe working in the region, what's advisable?
CJ: Check your immunization status or if you, for whatever reason, are not immunized or cannot be immunized, you may have to reevaluate travel. We do also have to appreciate that in Alberta, we do have a lot of mobility, which is fantastic, but it means that if there's community level transmission in the south, that can move to other regions of the province.
We continue to see cases in the north this week and we have large events coming. Between events such as Calgary Stampede and Rotary International that will see a lot of people come into the cities, there's a risk of measles transmission.
MH: During the pandemic, there was much made of the impact on the health system, overloaded hospitals.
If these measles cases are showing up in hospitals now and into the future, and in health clinics, what kind of impact does that have on the system itself?
CJ: Measles presents a huge strain, largely because we do not want people who are feeling under the weather or potentially exposed, just to walk into a walk-in health clinic or assessment centre.
We have to have special facilities or special handling for these cases. People who are sick with measles and require hospitalization.
Again, the infection controls are quite labour intensive. It requires a lot of space and a lot of staff in order to ensure that that virus does not spread to others in the hospital, often others who may be immunocompromised for various reasons.
MH: The province launched a new awareness campaign earlier this month. Changes have been made in making it easier to get vaccinated. How much of an impact is that having on the situation?
CJ: Advertising and advocacy are really the best tools we have. We just need to ensure there is a full press on this, and what I mean by that is although there are some commercials out there, they're not coming up every day in multiple formats.
In Calgary, I've only seen two or three of these commercials, despite the fact the campaign was launched nearly two weeks ago. So we really need to double down on this, we really need to convey that vaccines work, they're safe.
We've been vaccinated for measles now for about four decades and it was through vaccination that we were able to achieve a measles-free status for Canada, a status that you know we're at risk of losing over the next several months.