# Long-term impact of the COVID-19 pandemic on childhood vaccination coverage in Quebec, Canada: A cohort study from the Canadian immunization research network

## TL;DR

The study found that while most childhood vaccinations remained on track in Quebec after the pandemic, measles vaccination rates slightly dropped, highlighting the need for continued efforts to prevent outbreaks.

## Contribution

This study provides the first long-term assessment of pandemic effects on childhood vaccination coverage in Quebec using registry data.

## Key findings

- No decrease in coverage for vaccines administered before 12 months of age in 2023 compared to 2019.
- A slight decline in measles vaccine coverage was observed by 13 and 19 months of age in 2023.
- The mean number of days undervaccinated decreased from 158.8 in 2019 to 133.8 in 2023.

## Abstract

The COVID-19 pandemic disrupted routine childhood vaccination globally, increasing the risk of resurgences of vaccine-preventable diseases. This study assessed the long-term impact of the pandemic on vaccination coverage and timeliness for routine childhood immunizations for children born in 2017–2023.

We conducted a retrospective cohort study in Quebec, Canada, using data from the Quebec Immunization Registry. We compared age-appropriate vaccination coverage by 3, 5, 13 and 19 months of age and the cumulative days undervaccinated during the first 24 months of life, from 2019 to 2023.

There was no decrease in vaccination coverage by 3 and 5 months of age in 2023 compared to 2019 for DTaP, Hepatitis B, rotavirus and pneumococcal conjugate vaccines. We observed a 0.8 percentage point decline (95% confidence intervals (CI):-1.2,-0.4) for ≥1 dose of the measles vaccine by 13 months of age, and a 1.0 percentage point decline (95%CI:-1.5,-0.06) for ≥2 doses by 19 months of age in 2023 compared to 2019. Overall, the mean number of days undervaccinated decreased across birth cohorts from 158.8 in 2019 to 133.8 in 2023.

Delays in the administration of the measles vaccine remain concerning. Sustained efforts are needed to maintain high vaccination coverage and prevent outbreaks of vaccine-preventable diseases.

•This study evaluates the long-term impact of COVID-19 on childhood vaccination•No decrease in coverage for vaccines given before 12 months in 2023 versus 2019•Slight decline in measles vaccine coverage in 2023 versus 2019•Mean number of days undervaccinated decreased across cohorts from 2019 to 2023

This study evaluates the long-term impact of COVID-19 on childhood vaccination

No decrease in coverage for vaccines given before 12 months in 2023 versus 2019

Slight decline in measles vaccine coverage in 2023 versus 2019

Mean number of days undervaccinated decreased across cohorts from 2019 to 2023