School immunization coverage during the COVID-19 pandemic: A retrospective cohort study

  1. Hannah Sell
  2. Yuba Raj Paudel
  3. Donald Voaklander
  4. Shannon E. MacDonald

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Abstract

Few studies have assessed the impact of the COVID-19 pandemic on immunization coverage for adolescents, and little is known about how coverage has changed throughout the pandemic. We aimed to: (1) assess the change in coverage for school-based vaccines in Alberta, Canada resulting from the pandemic; (2) determine whether coverage differed by geographic health zone and school type; and (3) ascertain whether coverage has returned to pre-pandemic levels. Using a retrospective cohort design, we used administrative health data to compare coverage for human papillomavirus (HPV) and meningococcal conjugate A, C, Y, W-135 (MenC-ACYW) vaccines in Alberta, Canada between pre-pandemic (2017-2018 school year) and pandemic (2019-2020 and 2020-2021 school years) cohorts (N=289,420). Coverage was also compared by health zone and authority type. The 2019-2020 cohort was followed over one year to assess catch-up. Compared to 2017-2018, immunization coverage for HPV was significantly lower in the 2019-2020 (absolute difference: 60.8%; 95% CI: 60.4-61.3%) and 2020-2021 cohorts (absolute difference: 59.9%; 95% CI: 59.4-60.3%). There was a smaller, significant decline in MenC-ACYW coverage comparing 2017-2018 to 2019-2020 (absolute difference: 6.1%; 95% CI: 5.6-6.5%) and 2020-2021 (absolute difference: 32.2%; 95% CI: 31.6-32.7%). Private schools had low coverage overall, while coverage fluctuated by zone. During follow-up of the 2019-2020 cohort, coverage for HPV and MenC-ACYW increased from 5.6% to 50.2%, and 80.7% to 83.0%, respectively. There was a substantial decrease in school-based immunization coverage during the COVID-19 pandemic, and coverage has not returned to pre-pandemic levels, suggesting further catch-up is needed.

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  1. ScreenIT

    SciScore for 10.1101/2022.05.04.22274665: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: This study received approval from the Health Research Ethics Board at the University of Alberta (ethics ID: Pro00102401).
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    SAS version 9.4 (SAS Institute Inc.
    SAS Institute
    suggested: (Statistical Analysis System, RRID:SCR_008567)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Strengths and limitations: To our knowledge, this study is one of the first to assess how adolescent immunization coverage has changed over time during the COVID-19 pandemic and whether it has returned to pre-pandemic levels. A strength of our study was the use of a population-based repository that contains complete and timely information on all childhood immunizations, as well as complete denominator data. Data were included over a one-year period to determine whether coverage was recovering to pre-pandemic levels, which was previously unknown. A limitation is that there was a change in programming for the HPV vaccine during the 2018-2019 school year, moving from three doses in grade 5 to two doses in grade 6. As there were no HPV immunizations provided in this school year, we could not use this year for comparison. This meant that our definition of fully vaccinated was three or more doses for the 2017-2018 cohort, but two or more doses for the 2019-2020 and 2020-2021 cohorts. However, the percentage of individuals with two or more doses of HPV vaccine in the 2017-2018 cohort was 74.3%, so our difference in coverage estimates based on three dose coverage are conservative and with the same direction of effect (i.e., coverage is significantly lower in the pandemic cohorts in comparison to the pre-pandemic cohort). Additionally, as this study focused on immunization coverage for Albertan school children, findings may not be generalizable to other jurisdictions. Finally, as this...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

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  2. Version published to 10.1101/2022.05.04.22274665v1 on medRxiv