This is a summary, written by members of the CITF Secretariat, of:

Lee DID, Vanderhout S, Aglipay M, Birken CS, Morris SK, Piché‑Renaud, Keown-Stoneman CDG, Maguire JL. Delay in childhood vaccinations during the COVID‑19 pandemic. Canadian Journal of Public Health. 2022 Jan 20;113:126-134. doi:

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study, published in the Canadian Journal of Public Health, found that the frequency of on-time routine childhood vaccinations decreased during the first wave of the Covid-19 pandemic in Toronto. The researchers expressed concern that the observed delays in vaccination uptake may increase the risk of outbreaks of vaccine-preventable diseases. This study was conducted through the TARGet Kids! cohort study led by Dr. Jonathon Maguire (St. Michael’s Hospital, Unity Health Toronto) and Dr. Catherine Birken (Hospital for Sick Children). It included 1,277 healthy children aged 0-2 years who were receiving primary healthcare in Toronto between November 1, 2018, and May 31, 2020.

Key findings:

  • The proportion of on-time vaccinations decreased from 81.8% prior to the pandemic to 62.1% after the declaration of the pandemic emergency in Ontario on March 17, 2020. When stratified by age, the frequency of on-time vaccinations decreased in children aged 6 months, 15 months, and 18 months.
  • The odds of delayed vaccination were higher after the COVID-19 emergency than before. When stratified by age, this remained the case for vaccinations recommended at 6 months, 12 months, 15 months, and 18 months. The difference was not significant at 2 months and 4 months of age.
  • The median time to vaccination increased after the COVID-19 emergency from 5 days to 17 days. The hazard rate at which vaccinations occurred was lower for vaccinations recommended at 15 months and 18 months but was not significantly different for ages younger than 15 months.

One key limitation of the study was the relatively short observation window of just three months during the first wave of the pandemic, which prevented an assessment of whether there was a catch-up rebound in vaccinations. However, the study highlights the impact of public health emergencies on the capacity of primary healthcare clinics and staff to provide routine vaccinations. Delay in childhood vaccinations may lead to an increased risk of vaccine-preventable diseases.