Omicron and vaccines: An analysis on the decline in COVID-19 mortality

  1. Blas J. Larrauri
  2. Alejandro Malbrán
  3. José A. Larrauri

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Abstract

The SARS-CoV-2 virus emerged in December 2019 infecting more than 430 million people worldwide and causing almost 6 million deaths until February 2022. Rapid vaccination efforts during this period coincided with a reduction in the mortality rate of the virus. A new genetic COVID-19 variant named Omicron appeared and widely spread by the end of 2021, after which the COVID-19 mortality rate showed a marked, albeit temporary, decline. The potential relationship between vaccines and omicron infection on the mortality rate of COVID-19 is analyzed in this article using online data from public sources from countries with relatively high incidence of infection. Mortality and incidence rates were compared before and after Omicron became the prevalent source of COVID-19 cases, as well as the effect of vaccination during these periods. Infection rates were higher during Omicron than in the pre-Omicron period (4.16% vs. 2%, respectively), whereas mortality rates showed the opposite trend both in deaths over population (0.021% vs. 0.171%) and deaths over positive cases (0.27% vs. 1.07%, respectively). The results suggest that vaccines, while significantly reducing mortality, did not prevent Omicron infection; and that during the Omicron period mortality decreased by a low aggressiveness of this variant.

Key Messages

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    Vaccines do not appear to have prevented Omicron infection.

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    Infection rates were higher during the Omicron period than before it.

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    Mortality rates were lower during the Omicron period than before it.

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    Vaccines reduced mortality rates during both pre- and Omicron periods.

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    The sharp decrease in mortality rates during the Omicron period seems to be due to the low virulence of Omicron strains rather than vaccine efficacy.

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      SciScore for 10.1101/2022.05.20.22275396: (What is this?)

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

      Table 1: Rigor

      Ethicsnot detected.
      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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

      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.
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      • No protocol registration statement was detected.

      Results from scite Reference Check: We found no unreliable references.

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    2. Version published to 10.1101/2022.05.20.22275396v1 on medRxiv