Pandemic-related delays in routine childhood immunization rates are prompting concerns about the possible resurgence of vaccine-preventable illnesses in Alberta.
New York declared a state disaster emergency late last week as it scrambled to contain the polio virus, which has turned up in wastewater.
Alberta's chief medical officer of health, Dr. Deena Hinshaw, recently called on Albertans to ensure their vaccinations are up-to-date, warning diseases can be imported easily and spread quickly through the population, particularly in communities with lower immunization rates.
"The COVID-19 pandemic has interrupted routine childhood immunization schedules worldwide, leaving many at higher risk of vaccine-preventable diseases such as polio and measles," she said in a tweet.
The latest available provincial statistics show the percentage of Alberta children up-to-date (with four doses) of the shots containing the polio vaccine, by the age of two, dropped from 78.82 per cent in 2019 to 74.77 per cent last year.
That particular immunization also protects against other illnesses, including whooping cough, and infants are scheduled for four doses between birth and 18 months.
There was also a decline in measles vaccine coverage in children, with the percentage of seven-year-olds protected with two doses slumping to 75.84 per cent last year from 81.04 per cent in 2019.
"After about a year [into the pandemic], we were sitting with our infant vaccine coverage about five per cent below where it had been previously," said Shannon MacDonald, associate professor in the faculty of nursing and the school of public health at the University of Alberta.
"Now, where it was previously wasn't actually as high as it should be. We like to see those numbers up in the 90 per cent range."
MacDonald and her team have studied how the pandemic impacted immunization coverage among Alberta children.
According to MacDonald, the drop-off in school-based vaccinations — which protect against HPV, Hepatitis B and meningitis — was dramatic due to the initial shutdown of schools in March of 2020, followed by intermittent closures and online schooling the year after.
"The school age vaccines were really terribly impacted.… We've sort of got two years worth of kids that have fallen behind on those. And those coverage numbers fell from the 75 per cent range down to five per cent of kids fully vaccinated."
At Alberta Children's Hospital, infectious disease specialist Dr. Cora Constantinescu is watching the trends with a lot of trepidation.
She agrees access was hampered by school closures and the diversion of staff from public health clinics to deal with COVID-19.
"I am concerned that our own under-vaccinated and unvaccinated populations are going to see these diseases that we were hoping would be something we would never see again. But I think we're going to see them come back up, " Constantinescu said.
"We're seeing lower rates of childhood vaccines in terms of uptake currently and also … I believe there is some hesitancy that is at play and people are travelling a lot [again]. These are all good breeding grounds for infectious disease outbreaks."
According to Constantinescu, a large effort is underway to get Alberta children caught up on their routine vaccinations.
In a statement emailed to CBC News, Alberta Health acknowledged there has been a decrease in vaccination rates due to school closures and the redeployment of public health staff to COVID-19 assessment centres and immunization clinics.
"School immunization catch-up programs are ongoing and we expect to see school coverage rates … increasing as a result of these programs," spokesperson Charity Wallace said.
"To date, there has been no evidence of poliovirus in Alberta's wastewater. Should polio re-emerge in Canada, the Public Health Agency of Canada is positioned to collaborate with the provinces to quickly respond."
For her part, MacDonald believes it will take more funding to address the gaps in vaccine coverage for kids who missed doses due to the pandemic.
"It's going to take an additional investment of resources to get those kids caught up because you don't all of the sudden have extra vaccines and appointments and staff to catch people up," she said.
"Public health is stretched as it is. We need to make sure that they're adequately resourced to focus on this cohort of kids that got short shrift during the pandemic."