Impact of the COVID-19 pandemic on routine immunization coverage in children under 2 years old in Ontario, Canada: A retrospective cohort study

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.

Attendance and vaccination at immunization clinics in rural Gambia before and during the COVID-19 pandemic

“…The 38.3% reduction in average monthly immunizations during the COVID-19 interruption period in our study was lower compared to the 50-85% decline in vaccine administration in Sierra Leone [17] , 52.5% in Pakistan [6] , and 80.0% in Saudi Arabia [18] . Studies in Canada [19] , Turkey [20] , Lebanon [5] , and India [21] reported a lower reduction in average monthly immunization compared to our findings.…”

Population immunity to measles in Canada using Canadian Health Measures survey data – A Canadian Immunization Research Network (CIRN) study

“…This demographic shift has the potential to further lower population immunity. In addition, due to the COVID-19 pandemic, associated disruptions in primary care services and the likely decrease in routine vaccine coverage, future serosurveys are a priority in order to understand additional immunity gaps due to the pandemic [46] , [47] . Strategies to maintain high vaccination coverage and adequate immunity in all age groups are a priority to ensure that the chains of transmission following inevitable introductions from abroad remain short so that large measles outbreaks do not occur in the future.…”

Impact of COVID‐19 pandemic on reproductive, maternal, newborn, and child health care services in Phuentsholing General Hospital: A retrospective descriptive study

“…However, the immunization coverage was partially recovered towards the end of the year 2020 by improvising the vaccination strategies. 17 This study has found a profound impact of COVID-19 on the MCH services at Phuentsholing hospital. A similar impact must have been present in the rest part of the country in Bhutan.…”