Effectiveness of Vaccination against Reported SARS-CoV-2 Infection in United States Coast Guard Personnel between May and August 2021: A Time-Series Analysis

  1. John Iskander
  2. Jamie Frost
  3. Sharon Russell
  4. Jaspal Ahluwalia
  5. Emily Ward
  6. Shane Steiner
  7. Dana Thomas
  8. Paul Michaud

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Abstract

Background

The United States Coast Guard (CG) began voluntary use of SARS-CoV-2 vaccines under an Emergency Use Authorization on December 16, 2020. Vaccination status is monitored through a service-wide immunization registry. Active Duty and Reserve (military) CG members are required to report any new positive test for COVID-19 to a centralized database.

Methods

Between May and August 2021, vaccination effectiveness (VE) against any new report of COVID-19 was calculated according to standard formulas, using registry immunization status of cases and monthly mid-point vaccine coverage data. CG members recorded as fully vaccinated with a two-dose vaccine were compared with those with any other vaccine status. Sub-analyses were also conducted according to geographic area (Atlantic vs Pacific), age, and type of vaccine received.

Results

Effectiveness of full vaccination reached a peak of 89.0% in June, then declined over the rest of the study period to 62.7% in August. In July and August, steeper declines in VE were seen in the Atlantic region. The rate of breakthrough infections remained under 1% in two-dose vaccine recipients, and did not differ between those who received the Moderna or Pfizer vaccines. No hospitalizations or deaths due to COVID-19 disease were recorded in fully vaccinated Coast Guard members.

Conclusion

Coincident with the national spread of the Delta variant of SARS-CoV-2, overall vaccine effectiveness among CG personnel decreased during the summer months of 2021, but continued to provide substantial protection, as well as full protection against the most serious outcomes. Policy initiatives and outreach intended to increase vaccine coverage within this and other military populations could extend the disease prevention benefits seen in this study.

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  1. ScreenIT

    SciScore for 10.1101/2021.11.19.21266537: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: The CG Institutional Review Board reviewed the investigation proposal and deemed the project exempt from the requirements of 45 CFR 46.
    Sex as a biological variablenot detected.
    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 findings in this report are subject to at least four limitations. First, both COVID-19 case status and vaccination status are subject to underreporting. Verified vaccination status is subject to underreporting among civilians, which may have resulted in misclassification of some cases as not fully vaccinated. Though this could have biased VE estimates upward, the number of civilians reporting cases was small. Second, there may have been biased reporting of cases. With recent attention to breakthrough infections (Brown CM et al, 2021), there may have been preferential reporting of test positivity among fully vaccinated individuals. Such a pattern would have biased our VE estimates downward. Third, the current analysis does not take into account time since vaccination. As the apparent need for additional doses in the COVID-19 vaccine schedule emerges (Tré-Hardy M et al 2021), the lower VE estimates seen later in this study may partially reflect waning immunity for those with earlier vaccination dates (Fowlkes A et al, 2021, Mizrahi B et al, 2021). Older age may have also correlated with time since vaccination, since early U.S. COVID-19 vaccination strategies (which were reflected in initial CG vaccination policy) were primarily based on increasing age as a risk factor (Dooling K et al, 2020). In other words, within CG age may serve as a proxy measure for time since vaccination. Finally, several wide CI seen early in the study due to relatively small numbers of reported case...

    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

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1101/2021.11.19.21266537v1 on medRxiv