Effectiveness of an inactivated Covid-19 vaccine with homologous and heterologous boosters against Omicron in Brazil

  1. Otavio T. Ranzani
  2. Matt D. T. Hitchings
  3. Rosana Leite de Melo
  4. Giovanny V. A. de França
  5. Cássia de Fátima R. Fernandes
  6. Margaret L. Lind
  7. Mario Sergio Scaramuzzini Torres
  8. Daniel Henrique Tsuha
  9. Leticia C. S. David
  10. Rodrigo F. C. Said
  11. Maria Almiron
  12. Roberto D. de Oliveira
  13. Derek A. T. Cummings
  14. Natalie E. Dean
  15. Jason R. Andrews
  16. Albert I. Ko
  17. Julio Croda

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Abstract

The effectiveness of inactivated vaccines (VE) against symptomatic and severe COVID-19 caused by omicron is unknown. We conducted a nationwide, test-negative, case-control study to estimate VE for homologous and heterologous (BNT162b2) booster doses in adults who received two doses of CoronaVac in Brazil in the Omicron context. Analyzing 1,386,544 matched-pairs, VE against symptomatic disease was 8.6% (95% CI, 5.6–11.5) and 56.8% (95% CI, 56.3–57.3) in the period 8–59 days after receiving a homologous and heterologous booster, respectively. During the same interval, VE against severe Covid-19 was 73.6% (95% CI, 63.9–80.7) and 86.0% (95% CI, 84.5–87.4) after receiving a homologous and heterologous booster, respectively. Waning against severe Covid-19 after 120 days was only observed after a homologous booster. Heterologous booster might be preferable to individuals with completed primary series inactivated vaccine.

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  1. Version published to 10.1038/s41467-022-33169-0
  2. Version published to 10.1101/2022.03.30.22273193v2 on medRxiv
  3. ScreenIT

    SciScore for 10.1101/2022.03.30.22273193: (What is this?)

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

    Table 1: Rigor

    EthicsIACUC: This study was approved by the ethical committee for research of Federal University of Mato Grosso do Sul (CAAE: 43289221.5.0000.0021) The study population was adults (aged ≥18 years) residing in Brazil, and who underwent SARS-CoV-2 RT-PCR or rapid antigen testing associated with symptomatic illness13 during the study period.
    Sex as a biological variablenot detected.
    RandomizationAfter identification of each case, we randomly chose one control from the set of all eligible matching controls, allowing for replacement of controls between cases.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: Thank you for sharing your code and data.

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Some limitations should be acknowledged. The data available for this study was collected as part of Brazil’s passive surveillance efforts for Covid-19, so important covariates may be missing or incomplete. The distribution of RT-PCR tests and antigen tests, which have significantly different sensitivity, changed over the course of the study period, which could have led to a decrease in estimated VE during the Omicron period through misclassification. However, a sensitivity analysis restricted to RT-PCR tests produced similar results. In addition, the test-negative controls may have been different during the Omicron and Delta periods, which could explain some of the difference in VE estimates. In particular, a higher proportion of controls were hospitalized or died during the Delta period (Table 1), implying either that other pathogens with severe outcomes were circulating during that period, or that less testing was being done in the outpatient setting during the Delta period. Finally, differences in effectiveness and waning patterns by age could be driven by other factors, including occupational exposure (e.g., health care workers) and personal risk mitigation behavior. Overall, we found that primary vaccination with two doses of the CoronaVac vaccine provided 50-60% effectiveness against severe Covid-19 outcomes during the Omicron epidemic in Brazil, although effectiveness against symptomatic disease was close to zero. While a homologous booster afforded little additional p...

    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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  4. Version published to 10.1101/2022.03.30.22273193v1 on medRxiv