Effectiveness of Coronavirus Disease 2019 (COVID-19) Vaccines Among Incarcerated People in California State Prisons: Retrospective Cohort Study

  1. Elizabeth T Chin
  2. David Leidner
  3. Yifan Zhang
  4. Elizabeth Long
  5. Lea Prince
  6. Stephanie J Schrag
  7. Jennifer R Verani
  8. Ryan E Wiegand
  9. Fernando Alarid-Escudero
  10. Jeremy D Goldhaber-Fiebert
  11. David M Studdert
  12. Jason R Andrews
  13. Joshua A Salomon

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Abstract

Background

Prisons and jails are high-risk settings for coronavirus disease 2019 (COVID-19). Vaccines may substantially reduce these risks, but evidence is needed on COVID-19 vaccine effectiveness for incarcerated people, who are confined in large, risky congregate settings.

Methods

We conducted a retrospective cohort study to estimate effectiveness of messenger RNA (mRNA) vaccines, BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna), against confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among incarcerated people in California prisons from 22 December 2020 through 1 March 2021. The California Department of Corrections and Rehabilitation provided daily data for all prison residents including demographic, clinical, and carceral characteristics, as well as COVID-19 testing, vaccination, and outcomes. We estimated vaccine effectiveness using multivariable Cox models with time-varying covariates, adjusted for resident characteristics and infection rates across prisons.

Results

Among 60 707 cohort members, 49% received at least 1 BNT162b2 or mRNA-1273 dose during the study period. Estimated vaccine effectiveness was 74% (95% confidence interval [CI], 64%–82%) from day 14 after first dose until receipt of second dose and 97% (95% CI, 88%–99%) from day 14 after second dose. Effectiveness was similar among the subset of residents who were medically vulnerable: 74% (95% CI, 62%–82%) and 92% (95% CI, 74%–98%) from 14 days after first and second doses, respectively.

Conclusions

Consistent with results from randomized trials and observational studies in other populations, mRNA vaccines were highly effective in preventing SARS-CoV-2 infections among incarcerated people. Prioritizing incarcerated people for vaccination, redoubling efforts to boost vaccination, and continuing other ongoing mitigation practices are essential in preventing COVID-19 in this disproportionately affected population.

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  1. Version published to 10.1093/cid/ciab1032
  2. ScreenIT

    SciScore for 10.1101/2021.08.16.21262149: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: Study oversight: The study was approved by the institutional review board at Stanford University (protocol #55835).
    Sex as a biological variableWe did not adjust for sex because men and women are generally housed in separate prisons, making this variable highly collinear with prison.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    No key resources detected.

    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:
    The study has several other limitations. First, our estimates of effectiveness focused on confirmed infections, not other important outcomes, such as symptomatic infections or severe disease. Incidence of hospitalizations and deaths in our cohort during the study period was too low to support rigorous analysis of those outcomes, and symptom reporting is unreliable in carceral settings.23 A related point is that we were only able to estimate effectiveness in relation to the date of test sample collection, not transmission date, which allows for the possibility that some detected infections might have preceded vaccination. Second, we evaluated effectiveness against any SARS-CoV-2 infection, not specific viral variants, because CDCR conducted limited viral genome sequencing during the study period. As the B.1.617.2 (delta) variant became dominant and cases rose in the general community over the months of June and July,24,25 CDCR detected a total of 286 cases among a population of nearly 99,000 residents during this period,26 a substantially lower rate when compared to the period between mid-March 2020 to mid-February 2021, during which the number of cases were above 200 in almost every week, peaking at 5,659 weekly cases in December 2020. Low incidence after February 2021 suggests that there may be substantial protection against outbreaks in this population with high levels of vaccination and prior infections, including during a period marked by increasing prevalence of more hig...

    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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  3. Version published to 10.1101/2021.08.16.21262149v1 on medRxiv