Peer-reviewed article
Impact of the COVID-19 pandemic on routine immunization coverage in children under 2 years old in Ontario, Canada: A retrospective cohort study
Catherine Ji, Pierre‐Philippe Piché‐Renaud, Jemisha Apajee, Ellen Stephenson, Milena Forte et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study examined how COVID-19 disrupted routine childhood immunization in Ontario, Canada. Researchers tracked immunization rates for children under 2 years old from early 2019 through 2020 using electronic health records. Overall vaccination coverage dropped by 5.7% during the first wave of the pandemic (March-July 2020) and only partially recovered later that year. The largest declines occurred in older infants aged 15-18 months, with drops of around 15-16% in on-time vaccination rates. Recovery was incomplete by the end of 2020, raising concerns about future disease outbreaks.
Key points
- Overall up-to-date immunization coverage fell from 71.0% before the pandemic to 65.3% during March-July 2020
- On-time coverage at 15 months dropped by 14.7% and at 18 months by 16.4% during the peak pandemic period
- MMR vaccine coverage decreased by approximately 2% during and after the initial lockdown period
- Coverage partially recovered in the second half of 2020 but remained below pre-pandemic levels
- No specific sociodemographic group was differentially impacted; the decline affected all subgroups similarly
Limitations
The study only covers Ontario, Canada, and may not reflect experiences in other provinces or countries with different public health responses. The data ends in December 2020, so it cannot assess longer-term recovery or catch-up vaccination campaigns that may have occurred later.
Abstract
BACKGROUND: The COVID-19 pandemic has caused a disruption in childhood immunization coverage around the world. This study aimed to determine the change in immunization coverage for children under 2 years old in Ontario, Canada, comparing time periods pre-pandemic to during the first year of the pandemic. METHODS: Observational retrospective open cohort study, using primary care electronic medical record data from the University of Toronto Practice-Based Research Network (UTOPIAN) database, from January 2019 to December 2020. Children under 2 years old who had at least 2 visits recorded in UTOPIAN were included. We measured up-to-date (UTD) immunization coverage rates, overall and by type of vaccine (DTaP-IPV-Hib, PCV13, Rota, Men-C-C, MMR, Var), and on-time immunization coverage rates by age milestone (2, 4, 6, 12, 15, 18 months). We compared average coverage rates over 3 periods of time: January 2019-March 2020 (T1); March-July 2020 (T2); and August-December 2020 (T3). RESULTS: 12,313 children were included. Overall UTD coverage for all children was 71.0% in T1, dropped by 5.7% (95% CI: -6.2, -5.1) in T2, slightly increased in T3 but remained lower than in T1. MMR vaccine UTD coverage slightly decreased in T2 and T3 by approximately 2%. The largest decreases were seen at ages 15-month and 18-month old, with drops in on-time coverage of 14.7% (95% CI: -18.7, -10.6) and 16.4% (95% CI: -20.0, -12.8) respectively during T2. When stratified by sociodemographic characteristics, no specific subgroup of children was found to have been differentially impacted by the pandemic. CONCLUSION: Childhood immunization coverage rates for children under 2 years in Ontario decreased significantly during the early period of the COVID-19 pandemic and only partially recovered during the rest of 2020. Public health and educational interventions for providers and parents are needed to ensure adequate catch-up of delayed/missed immunizations to prevent potential outbreaks of vaccine-preventable diseases.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Continuation of routine immunization services during COVID-19 pandemic (observed)
- Population
- 12,313 children under 2 years old in Ontario, Canada with at least 2 visits recorded in primary care electronic medical records
Key finding
Overall up-to-date immunization coverage decreased by 5.7% (95% CI: -6.2, -5.1) during March-July 2020 compared to pre-pandemic period