SARS-CoV-2 Breakthrough Infections among the Healthcare Workers Post-Vaccination with ChAdOx1 nCoV-19 Vaccine in the South Indian State of Kerala

  1. Aleena Issac
  2. Jose J Kochuparambil
  3. Linu Elizabeth

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

Objective

The national COVID-19 vaccination campaigns in India, prioritized healthcare workers to be vaccinated with ChAdOx1 nCoV-19 (AZD1222). So, we aimed to ascertain the effectiveness of ChAdOx1 nCoV-19 vaccine among the healthcare workers by characterizing the breakthrough infections which occurred 14 days after the second dose of the vaccine.

Methods

We prospectively evaluated the ‘Institutional Covid Vaccination Database’ to categorize the SARS-CoV-2 positive healthcare workers into 2 cohorts: infected vaccinated and infected unvaccinated cohort. Along with comparing the descriptive statistics of the cohorts, the relative risk (RR), relative risk reduction (RRR), and the vaccine effectiveness were calculated. The study population was compared for the significant difference by using the parametric model (binary logistic regression) for the Odds ratio and the non-parametric model (cox proportionality model) for the Hazard ratio.

Results

Out of the 324 healthcare workers employed in our institution 243 (75%) were vaccinated. When 6.58% (16) of the vaccinated healthcare workers were tested positive, 43.75% (35) were infected in the unvaccinated cohort and the median time of infection in the vaccinated cohort was 65 days (range 20 -91 days). While the cox proportionality model reveals that the age, sex, and the contact exposure status of the cohort are not significant factors for getting infected after being vaccinated, binary logistic regression proves that a significant relationship exists between the incidence of infection and the unvaccinated status (p = 0.001, OR = 4.278). Completing the two-dose of vaccination decreased the hazard of testing positive for the SARS-CoV-2 by 84.96 % when compared with the unvaccinated individuals, which is the effectiveness of the ChAdOx1 nCoV-19 vaccine.

Conclusion

There is an increased risk of the third wave of COVID-19 infection in the upcoming months. So, primary infection control measures should be followed even if vaccinated, to prevent the risk of breakthrough infections.

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2021.08.07.21261587: (What is this?)

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

    Table 1: Rigor

    EthicsField Sample Permit: The data collection was conducted till July 15, 2021.
    IACUC: Research Ethics Approval: Ethical approval is granted by the Institutional Ethical Committee of Mary Queen’s Mission Hospital (MQMH/IRB/21-23-00) upon ensuring the confidentiality of the personal information of the Hospital staff.
    Consent: Written consent was waived and verbal consent is obtained prior to the data collection.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Data were analyzed using SPSS version 20.
    SPSS
    suggested: (SPSS, RRID:SCR_002865)

    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:
    Limitations of the study is that this is a monocentric, observational study design with a small sample size and also the inability to adjust the confounding variables. Also, the study doesn’t compare the efficacy of various other vaccines available in India. Another limitation is that we don’t evaluate the immunogenicity of the vaccinated individuals and the results address the short-term effect of the vaccine. We need multi-national studies with a large sample size to provide more accurate results. Breakthrough infections among the healthcare workers amid vaccination campaigns remain a concern for all authorities worldwide. As plotted in the dotted linear forecast (Figure 2), there is an increased risk of the third wave of COVID-19 infection in the coming months. So, the basic infection control measures including face masking, hand hygiene, social distancing, and quarantine protocols should be followed even if vaccinated, to prevent the risk of breakthrough infections.

    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 10.1101/2021.08.07.21261587v1 on medRxiv