JMIR Publications

ABSTRACT

Background:

The COVID-19 pandemic caused interruptions in school-based vaccine delivery, resulting in significant decreases in coverage among school-aged children.

Objective:

To assess the impact of the COVID-19 pandemic and ongoing catch-up immunization efforts on vaccine coverage among school-aged children in the Canadian province of Alberta.

Methods:

We used population-wide administrative health data to calculate monthly cumulative vaccine coverage among Grade 1, 6, and 9 cohorts, comparing four pandemic cohorts (2019-20, 2020-21, 2021-22, and 2022-23 grade-years) to a pre-pandemic cohort for each grade. For each vaccine, we calculated vaccine coverage deficits remaining at the end of the study period, and estimated time to clear those deficits based on observed catch-up immunization rates.

Results:

All Grade 6 pandemic cohorts had lower coverage at the end of the school year (3-65 percentage points lower), though coverage had increased to near pre-pandemic levels after approximately three years of follow-up. Coverage among the Grade 1 and 9 cohorts remained below pre-pandemic levels at study end; the additional catch-up time required was estimated at 2 and 3 years, respectively.

Conclusions:

Partial recovery of vaccine coverage was found for cohorts impacted by interruptions to school-based programming during the COVID-19 pandemic. Further efforts to alleviate coverage deficits among Grade 1 cohorts may be addressed in routine Grade 6 programs, while targeted efforts in post-secondary institutions may be required to address delays in Grade 9 immunizations.