Canada's Childhood Immunization Catch-Up Gap, and the Fix

Canada’s national DTaP coverage at age two sits at 77.1%, well short of the 95% goal, and Alberta alone confirmed more than 2,000 measles cases in 2025, most of them in people with no measles vaccine on record (Public Health Agency of Canada; Government of Alberta). The gap is rarely about parents refusing vaccines outright. Most of it is doses that were never rebooked once the schedule slipped, sitting inside a recall system built around who calls in rather than who is overdue.

The coverage numbers PHAC has been reporting for years

The Public Health Agency of Canada runs the Childhood National Immunization Coverage Survey (cNICS) every two years, and the most recent published results are not close to reassuring. At age two, national DTaP-containing vaccine coverage was 77.1%, Hib coverage was 75.3%, and even measles-containing vaccine coverage sat at 91.6%, all below the 95% national goal set for that age group (PHAC, 2021 cNICS highlights). PHAC’s own summary is blunt about it: none of Canada’s national coverage goals were met for any age group in that survey, with a single exception, one dose of Tdap by age 17.

What makes this a catch-up problem rather than a one-time miss is what happened between ages two and seven. PHAC reported that DTaP coverage at age seven fell a further six percentage points compared with the 2019 survey, and measles coverage fell four points over the same window. Those are children who started their schedule and then dropped off it somewhere between the toddler visits and the school-entry check, without anyone in the system flagging the gap loudly enough to close it before the next survey ran.

What that gap looks like in an actual outbreak

Coverage statistics are abstract until a province has to live with the consequence. Alberta reported 2,008 confirmed measles cases in 2025, a scale of transmission the province had not seen in a generation, and 1,804 of those cases were in people with no documented measles vaccine at all, against only 78 who had received the recommended two doses (Government of Alberta, Measles – Data and statistics). That works out to roughly nine in ten cases occurring in someone the system had never fully protected.

Children carried a disproportionate share of it. Of Alberta’s 2025 cases, 580 were in children under five and another 889 were between five and seventeen — together, close to three-quarters of everyone infected. This is precisely the age band a functioning catch-up recall system exists to protect: children who are past their first doses but not yet caught up on boosters, sitting in a practice’s own roster the whole time.

Catch-up is a provincial responsibility, and it rarely happens on its own

Unlike a single national health service, Canada delivers childhood immunization through a patchwork of family practices, pediatric clinics, walk-in clinics and public health units, and each province decides how, or whether, a missed dose gets chased down. Ontario and New Brunswick are the outliers, with school-entry immunization laws that require up-to-date records and can suspend a child who is not caught up, which at least forces a conversation once a year. Everywhere else, there is no equivalent backstop. A missed second MMR dose, a delayed DTaP-IPV-Hib booster, a Tdap that never got scheduled at the school-age visit: none of it trips an automatic follow-up unless the practice itself is set up to notice and act on the gap.

That structure puts the entire burden of catch-up on the individual clinic’s own systems, at exactly the moment those clinics are already stretched thin on scheduling, intake and everything else that competes for front-desk time. A practice with a strong internal recall habit closes its gaps; a practice without one accumulates them quietly, one missed booster at a time, until a case like Alberta’s shows up on the doorstep of a community that assumed it was protected.

Why the paper-based recall model quietly fails

Every province runs some version of a reminder system for childhood immunization, and on paper, the process looks sound: a schedule is set, a chart flags the next dose, and a family is supposed to book before the interval closes. In practice, the system depends on a family noticing a gap themselves, or on front-desk staff finding the hour it takes to pull overdue charts, call each one, leave a message, wait, and call again, on top of the calls that are already ringing in. Public Health Agency of Canada’s own measles surveillance guidance is explicit that Canada’s vaccination rates, while generally high, sit “below the level needed for community immunity in some areas” (PHAC, Measles: Monitoring and surveillance). That is a fairly polite way of describing exactly the pattern Alberta’s case data shows: pockets of under-immunized families that a reactive, inbound-only system never reaches.

PHAC’s own 2024 seasonal coverage survey adds a useful signal here. Children whose families had completed all recommended routine vaccines were far more likely to also be up to date on seasonal COVID-19 and influenza doses — 70%, against only 38% for children with some routine doses missing and 11% for those with none (PHAC, Childhood Seasonal Immunization Coverage Survey 2024). Under-immunization does not spread evenly across a roster — it clusters in the same families, visit after visit, and a practice that never systematically follows up on the first missed dose is the same practice that keeps missing every dose after it.

What automatic recall changes for a practice

This is the part of the workflow Arbol was built to run without adding staff hours. Instead of a chart flag that waits for someone to act on it, Arbol cross-references a practice’s own patient roster against each vaccine’s due-by age and reaches out automatically, by phone call, text message or WhatsApp, in whichever channel the family actually responds to, the moment a dose comes due rather than months after it is overdue. The same contact lets the family confirm a slot, book one on the spot, or reschedule, and Arbol follows up again if nobody replies the first time, closing the loop that a one-shot mailed reminder never does.

None of this requires the practice to change how it runs immunization clinically. It changes who initiates contact. A roster of two hundred children behind on a second MMR dose does not need two hundred phone calls made one at a time between other duties — it needs a system that starts every one of those conversations on schedule, confirms the ones that book, and flags the ones that still need a human follow-up.

The clinical decisions stay exactly where they belong, with the family physician, pediatrician or immunizing nurse. What moves is the administrative weight of finding two hundred families at the right moment, without that task competing with everyone already in the waiting room. A practice that has never run a proactive recall program tends to assume it would need extra staff to do this well. More often, the bottleneck was never staff willingness. It was the hours it takes one person to work a stale list by hand while the phone keeps ringing with everything else the clinic already has to answer.

1. 1
   Pull the age-eligible list, not the appointment list

   Cross the practice's roster against each vaccine's due-by age — not against who has already called in. That is where every missed catch-up dose is hiding.

2. 2
   Reach every family the same week

   Arbol places the calls, texts or WhatsApp messages automatically, in the family's preferred channel, instead of waiting for a quiet moment at the front desk.

3. 3
   Let the first message book the slot

   A reminder that a child is behind on a dose should let the parent book or confirm right there, not send them into a phone queue to do it.

4. 4
   Confirm ahead of time, and re-open any slot that goes unanswered

   Automatic confirmation a day or two before the visit, and automatic rebooking when a family doesn't respond, keeps a missed reminder from quietly becoming a missed dose again.

What this means for the next survey

PHAC will run the next cNICS on its usual two-year cycle, and the honest expectation, based on the 2021 results, is that age-seven coverage keeps drifting unless something changes how catch-up doses actually get booked. Alberta’s 2025 case count is what that drift looks like once a province stops being able to absorb it quietly. The 580 children under five and 889 children and teens who caught measles in Alberta last year were, almost without exception, sitting on a clinic’s own patient list the whole time. They were not missing from the system, just not yet reached by it.

A practice does not need to wait for a provincial mandate to close that gap on its own roster. The tools already used for other outreach, automatic reminders, confirmation and rebooking by phone, text or WhatsApp, apply just as directly to a second MMR dose as they do to a routine check-up. If you run scheduling for a family practice or pediatric clinic in Canada, this is the same operational problem behind how the UK is closing its own catch-up gap and what Australia’s immunisation catch-up data shows, and it connects to how Arbol works for practices that want recall to run itself instead of competing for staff time against everything else on the schedule.