Thousands of children lack protection against measles and other diseases in Ottawa because they didn't receive routine vaccinations during the pandemic, according to new data from Ottawa Public Health.

Ottawa Public Health (OPH) gauges vaccine uptake by tracking the number of vaccine supply orders it receives from health-care providers who administer shots.

The latest data available suggest orders for the MMR vaccine that protects against measles, mumps and rubella, along with the MMR-V vaccine that protects those three diseases plus varicella (chickenpox), decreased by 30 per cent in 2020 compared to the typical number of orders in pre-pandemic years.

Orders for the measles-containing vaccine continued to slump in 2022 compared years prior to 2020 — down between 10 and 20 per cent, said OPH.

"Based on this distribution data, we estimate approximately 15,000 kids in Ottawa missed receiving a dose of MMR or MMR-V between 2020 and 2022," said an OPH spokesperson in an email to CBC.

Measles is a highly contagious infectious disease that used to infect most children until a vaccine was introduced in the 1960s. According to Public Health Ontario, globally, measles remains the leading cause of death in children by a vaccine-preventable disease — an average of one to two children die for every 1,000 cases.

Two shots of the MMR vaccine provide nearly 100 per cent protection from getting measles for life.

"It's always concerning to hear that some children may not be up to date because it means that they're not adequately protected against disease that we have vaccines to protect them for," said Marie-Claude Turcotte, manager of immunization at OPH.

Public health officials previously warned the drop in vaccine coverage heightens the risk of a measles outbreak in the city because measles is so contagious.

Efforts to catch up

Data for last year shows the volume of orders for all routine vaccines is still 10 per cent behind where it was before 2020, said Turcotte, though the number is better than 2020 and 2021.

According to OPH, the five-in-one vaccine (diphtheria, tetanus, pertussis, polio and haemophilus influenzae type b), usually given at a baby's six month appointment, saw little to no changes in volumes ordered during the pandemic.

Ottawa also suspended its participation in the school-age vaccine tracking program through Ontario's Panorama database for two school years, 2020-2021 and 2021-2022.

The program prompts parents to notify OPH what vaccines their child has received as required by Ontario's Immunization of School Pupils Act. Late in 2022, the public health agency resumed the program and sent notices to more than 12,000 students who were born in 2005 and 2015.

"That's a reminder to parents to go and get the child vaccinated," she said.

Even 'small' drop makes difference: researcher 

When it comes to measles and whooping cough, every new child vaccinated makes a difference, said Dr. Kumanan Wilson, a professor of medicine at the University of Ottawa and the chief science officer at CANImmunize, an Ottawa-based company that creates software to track immunizations.

"These are some of our most infectious viruses so we need to have high vaccine coverage," he said. "Even a small drop in coverage for measles can result in outbreaks."

Wilson said CANImmunize, which runs a free app that allows parents to track their children's vaccinations, reported a drop in new registrations during the pandemic.

"We're still lagging somewhat," he said earlier this week.

The company is currently working with CHEO and Kids Come First to design software that will allow parents in Ottawa, those who live in the Renfrew County and District Health Unit, and those living in the Leeds, Grenville and Lanark District Health Unit, to book vaccine appointments for their children online.

It is expected to be available to parents in May, the company said.

While Ottawa sees one to two per cent of children go without vaccines due to conscientious or religious objections to vaccines, Wilson believes confusion is a large driver behind the vaccine lag, not hesitancy.

"We like to talk a lot about vaccine hesitancy and the anti-vaccine movement but really, logistics is often at the root of a lot of these problems," he said.

Wilson said he hopes new tools will help streamline the process and improve the booking process, increasing vaccine coverage. The new software coming in May will also make it easier for health units to track vaccine uptake, if parents consent to sharing that information.

OPH has also expanded routine vaccinations available at its family and community vaccination clinics and wellness hubs. Parents who do not have a family doctor, or another health-care provider, can book a vaccine appointment through its website at one of the clinics.