Impact of the COVID-19 pandemic on routine immunization coverage of children and teenagers in Ontario, Canada

Affiliations

¹ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Toronto Western Family Health Team, University Health Network, 440 Bathurst Street, 3rd Floor, Toronto, Ontario M5T 2S6, Canada. Electronic address: catherine.ji@uhn.ca.
² Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.
³ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada.
⁴ Toronto Public Health, 277 Victoria Street, 5th Floor, Toronto, Ontario M5B 1W2, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada.
⁵ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Mount Sinai Academic Family Health Team, Sinai Health System, 60 Murray Street, 4th Floor, Toronto, Ontario M5T 3L9, Canada.
⁶ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Toronto Western Family Health Team, University Health Network, 440 Bathurst Street, 3rd Floor, Toronto, Ontario M5T 2S6, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; ICES, V Wing, V1-06, s2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada; Public Health Ontario, 661 University Avenue, Suite 1701, Toronto, Ontario M5G 1M1, Canada.
⁷ Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; Department of Pediatrics, Temerty Faculty of Medicine, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; Division of Infectious Diseases, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.
⁸ Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; ICES, V Wing, V1-06, s2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada; Public Health Ontario, 661 University Avenue, Suite 1701, Toronto, Ontario M5G 1M1, Canada.
⁹ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Toronto Western Family Health Team, University Health Network, 440 Bathurst Street, 3rd Floor, Toronto, Ontario M5T 2S6, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; North York General Hospital, 4001 Leslie Street, Toronto, Ontario M2K 1E1, Canada.

PMID: 39889534
DOI: 10.1016/j.vaccine.2025.126811

Free article

Impact of the COVID-19 pandemic on routine immunization coverage of children and teenagers in Ontario, Canada

Catherine Ji et al. Vaccine. 2025.

Free article

. 2025 Mar 7:49:126811.

doi: 10.1016/j.vaccine.2025.126811. Epub 2025 Jan 30.

Authors

Affiliations

¹ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Toronto Western Family Health Team, University Health Network, 440 Bathurst Street, 3rd Floor, Toronto, Ontario M5T 2S6, Canada. Electronic address: catherine.ji@uhn.ca.
² Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.
³ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada.
⁴ Toronto Public Health, 277 Victoria Street, 5th Floor, Toronto, Ontario M5B 1W2, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada.
⁵ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Mount Sinai Academic Family Health Team, Sinai Health System, 60 Murray Street, 4th Floor, Toronto, Ontario M5T 3L9, Canada.
⁶ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Toronto Western Family Health Team, University Health Network, 440 Bathurst Street, 3rd Floor, Toronto, Ontario M5T 2S6, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; ICES, V Wing, V1-06, s2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada; Public Health Ontario, 661 University Avenue, Suite 1701, Toronto, Ontario M5G 1M1, Canada.
⁷ Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; Department of Pediatrics, Temerty Faculty of Medicine, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; Division of Infectious Diseases, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.
⁸ Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; ICES, V Wing, V1-06, s2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada; Public Health Ontario, 661 University Avenue, Suite 1701, Toronto, Ontario M5G 1M1, Canada.
⁹ Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, 500 University Avenue, 5th Floor, Toronto, Ontario M5G 1V7, Canada; Toronto Western Family Health Team, University Health Network, 440 Bathurst Street, 3rd Floor, Toronto, Ontario M5T 2S6, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada; North York General Hospital, 4001 Leslie Street, Toronto, Ontario M2K 1E1, Canada.

PMID: 39889534
DOI: 10.1016/j.vaccine.2025.126811

Abstract

Objectives: To assess immunization coverage for routine vaccinations in children (aged 4-7 years) and teenagers (aged 14-17 years) during the COVID-19 pandemic compared to the pre-pandemic period, in Ontario, Canada.

Methods: Retrospective cohort study using primary care electronic medical records data from the University of Toronto Practice-Based Research Network database from January 2018 to June 2022. Monthly estimates of vaccine up-to-date (UTD) coverage (defined as 1 dose of tetanus, diphtheria, and acellular pertussis (Tdap)-containing and 1 dose of measles, mumps and rubella-containing vaccines received after the 4th birthday for children; and 1 dose of Tdap-containing vaccine received after the 14th birthday for teenagers) and time series regression analysis were used to compare changes in mean coverage before and during the pandemic. We also examined if changes in coverage estimates over time were associated with sociodemographic factors.

Results: 30,010 children and 31,624 teenagers were included. Mean monthly UTD coverage for children decreased significantly from 48.7 % (SD 2.1) pre-pandemic (January 2018 - February 2020) to 44.3 % (SD 1.3) in mid-pandemic period (July 2020-June 2021), and remained significantly lower in later pandemic period (July 2021 - June 2022). Mean monthly UTD coverage for teenagers was 34.6 % (SD 0.9) pre-pandemic and decreased to 16.7 % (SD 0.6) in later pandemic period. When adjusted for baseline differences, teenagers from neighborhoods with higher income, lower proportions of racialized and newcomer populations and from rural areas experienced larger decreases in UTD coverage during the pandemic. No significant differences were found in UTD coverage among children across the various sociodemographic factors.

Conclusion: Significant declines in immunization coverage for children and teenagers in Ontario were still observed by June 2022, highlighting the need to further study the long-term impact of the pandemic and implement effective catch-up interventions to increase immunization coverage and prevent outbreaks of vaccine-preventable diseases.

Keywords: COVID-19; Electronic Health Records; Health services; Observational Study; Primary Health Care; Vaccination coverage.

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Conflict of interest statement

Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Catherine Ji reports financial support was provided by Canadian Institutes of Health Research. Catherine Ji reports a relationship with Pfizer Canada ULC that includes: funding grants. Pierre-Philippe Piche-Renaud reports a relationship with Pfizer Canada ULC that includes: funding grants. Shaun K Morris reports a relationship with Pfizer Canada ULC that includes: consulting or advisory and funding grants. Shaun K Morris reports a relationship with GlaxoSmithKline Inc that includes: consulting or advisory and speaking and lecture fees. Shaun K Morris reports a relationship with Sanofi Pasteur Inc that includes: consulting or advisory and speaking and lecture fees. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Impact of the COVID-19 pandemic on routine immunization coverage of children and teenagers in Ontario, Canada

Affiliations

Impact of the COVID-19 pandemic on routine immunization coverage of children and teenagers in Ontario, Canada

Authors

Affiliations

Abstract

Conflict of interest statement

Publication types

MeSH terms

Substances

LinkOut - more resources

Full Text Sources

Medical