Coronavirus Disease 2019 Vaccine Boosting in Previously Infected or Vaccinated Individuals

  1. Nabin K Shrestha
  2. Priyanka Shrestha
  3. Patrick C Burke
  4. Amy S Nowacki
  5. Paul Terpeluk
  6. Steven M Gordon

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Abstract

Background

The purpose of this study was to determine whether boosting previously infected or vaccinated individuals with a vaccine developed for an earlier variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protects against the Omicron variant.

Methods

Employees of Cleveland Clinic, previously infected with or vaccinated against coronavirus disease 2019 (COVID-19) and working the day the Omicron variant was declared a variant of concern, were included. The cumulative incidence of COVID-19 was examined over 2 months during an Omicron variant surge. Protection provided by boosting was evaluated using Cox proportional hazards regression. Analyses were adjusted for time since proximate SARS-CoV-2 exposure.

Results

Among 39 766 employees, 8037 (20%) previously infected and the remaining previously vaccinated, COVID-19 occurred in 6230 (16%) during the study. Risk of COVID-19 increased with time since proximate SARS-CoV-2 exposure, and boosting protected those >6 months since prior infection or vaccination. In multivariable analysis, boosting was independently associated with lower risk of COVID-19 among those vaccinated but not previously infected (hazard ratio [HR], .43; 95% confidence interval [CI], .41–.46) as well as those previously infected (HR, .66; 95% CI, .58–.76). Among those previously infected, receipt of 2 compared with 1 dose of vaccine was associated with higher risk of COVID-19 (HR, 1.54; 95% CI, 1.21–1.97).

Conclusions

Administering a COVID-19 vaccine not designed for the Omicron variant >6 months after prior infection or vaccination protects against Omicron variant infection. There is no advantage to administering more than 1 dose of vaccine to previously infected persons.

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  1. Version published to 10.1093/cid/ciac327
  2. ScreenIT

    SciScore for 10.1101/2022.02.10.22270744: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: The study was approved by the Cleveland Clinic Institutional Review Board as exempt research (IRB no. 21-1163).
    Consent: A waiver of informed consent and waiver of HIPAA authorization were approved to allow access to de-identified health information by the research team.
    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 study has its limitations. Individuals with unrecognized asymptomatic prior infections would have been misclassified as previously uninfected, resulting in underestimating the protective effect of prior infection. Many asymptomatic incident infections were probably missed. There is little reason to suppose, however, that they would have been missed in the various groups at rates disproportionate enough to change the directionality of the study’s findings. Because our employee health symptom-monitoring processes were overwhelmed by disease volume during the Omicron phase of the pandemic, we were unable to distinguish between symptomatic and asymptomatic infections and had to limit our analyses to all detected infections. We did not have a way to adjust for behavioral differences and household exposures, both of which can strongly influence risk of COVID-19. Our study of healthcare personnel included no children and few elderly subjects, and the majority would not have been immunocompromised. Lastly, knowing that the Omicron variant causes milder infection than the Delta variant, the clinical impact of protective effect of vaccine boosting on severe infections would be smaller than the protective effect on infections overall that this study found. The findings of this study have important implications. Those who have had COVID-19 are better protected against the Omicron variant than those who received two doses of an mRNA COVID-19 vaccine, with protection lasting at least 6...

    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 10.1101/2022.02.10.22270744 on medRxiv