Vaccine-preventable diseases such as measles or chickenpox and others, which have been seen in other parts of the world and spread rapidly in Canada due to decreased routine vaccinations during the COVID-19 pandemic, pediatricians say urging parents to ensure their children are fully immunized.

Provinces and territories have also recorded data on vaccinations administered against infectious diseases such as measles, diphtheria, polio, and whooping cough, as well as vaccines against other diseases given in school immunization clinics.

Although much of the current data does not cover years beyond 2019, provinces with more recent figures are already witnessing a significant decline in routine vaccinations.

Also, pediatricians are concerned about the potential outbreak of vaccine-preventable diseases if a very large number of children are immunocompromised or not vaccinated at all while public health clinics focus on COVID-19 vaccines. The spread of school closures and misinformation about vaccines has affected some parents against immunization efforts, complicating matters further.

Recent data from Public Health Ontario also indicates that vaccination against hepatitis B infection for children aged 12 has dropped to about 17 percent in the 2020 to 2021 school year, compared to 67 percent in the school year ending in 2019.

For human papillomavirus, which can cause cancer, vaccination rates were even lower, dropping to 0.8 percent last year compared to 58 percent in 2019. As for the meningococcal vaccine, which helps protect against four types of bacteria that cause a rare disease, vaccinations dropped to about 17 percent from 80 percent during the same period. Risks of this deadly disease include meningitis and inflammation of the membranes of the brain and spinal cord.

In this regard, Public Health Ontario said in a statement: "The significant decline in coverage in 2019-20 and 2020-21 illustrates the impact of the COVID-19 pandemic, where there was limited capacity to deliver vaccination programs in schools." It said that data on vaccine uptake aimed at protecting young children from measles, for example, is not yet available after 2019, and a report on subsequent figures is expected to be released next spring.

Dr. Monica Nos, the medical director of immunization programs and vaccine-preventable disease service at the British Columbia Centre for Disease Control, said school vaccines, starting from grade six, have been delayed, but work is underway to return to pre-pandemic levels.

Additionally, Dr. Sam Wong, medical director of the Canadian Paediatric Society, said that misinformation and vaccine hesitancy during the pandemic, "along with the failure of the public health system" to provide routine vaccines, means some populations could be left vulnerable to severe rates of diseases such as measles, which spreads through coughing and sneezing.

Wong said it is important for doctors and parents to discuss the importance of routine vaccines that have proven effective for decades, adding that some people believe that young children's immune systems are not ready, so they prefer to wait until they grow older.