Is increased mortality by multiple exposures to COVID-19 an overseen factor when aiming for herd immunity?

  1. Kristina Barbara Helle
  2. Arlinda Sadiku
  3. Girma Mesfin Zelleke
  4. Toheeb Babatunde Ibrahim
  5. Aliou Bouba
  6. Henri Christian Tsoungui Obama
  7. Vincent Appiah
  8. Gideon Akumah Ngwa
  9. Miranda Ijang Teboh-Ewungkem
  10. Kristan Alexander Schneider

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Abstract

Governments across the globe responded with different strategies to the COVID-19 pandemic. While some countries adopted measures, which have been perceived controversial, others pursued a strategy aiming for herd immunity. The latter is even more controversial and has been called unethical by the WHO Director-General. Inevitably, without proper control measures, viral diversity increases and multiple infectious exposures become common, when the pandemic reaches its maximum. This harbors not only a potential threat overseen by simplified theoretical arguments in support of herd immunity, but also deserves attention when assessing response measures to increasing numbers of infection.

Methods and findings

We extend the simulation model underlying the pandemic preparedness web interface CovidSim 1.1 ( http://covidsim.eu/ ) to study the hypothetical effect of increased morbidity and mortality due to ‘multi-infections’, either acquired at by successive infective contacts during the course of one infection or by a single infective contact with a multi-infected individual. The simulations are adjusted to reflect roughly the situation in the USA. We assume a phase of general contact reduction (“lockdown”) at the beginning of the epidemic and additional case-isolation measures. We study the hypothetical effects of varying enhancements in morbidity and mortality, different likelihoods of multi-infected individuals to spread multi-infections and different susceptibility to multi-infections in different disease phases. It is demonstrated that multi-infections lead to a slight reduction in the number of infections, as these are more likely to get isolated due to their higher morbidity. However, the latter substantially increases the number of deaths. Furthermore, simulations indicate that a potential second lockdown can substantially decrease the epidemic peak, the number of multi-infections and deaths.

Conclusions

Enhanced morbidity and mortality due to multiple disease exposure is a potential threat in the COVID-19 pandemic that deserves more attention. Particularly it underlines another facet questioning disease management strategies aiming for herd immunity.

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  1. Version published to 10.1371/journal.pone.0253758
  2. ScreenIT

    SciScore for 10.1101/2020.10.22.20217638: (What is this?)

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

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    The code was implemented in Python 3.8 using the function solve ivp as part of the library Scipy, and library Numpy.
    Scipy
    suggested: (SciPy, RRID:SCR_008058)
    Numpy
    suggested: (NumPy, RRID:SCR_008633)
    Graphical output was created in Python 3.8.
    Python
    suggested: (IPython, RRID:SCR_001658)
    using library Matplotlib.
    Matplotlib
    suggested: (MatPlotLib, RRID:SCR_008624)

    Results from OddPub: Thank you for sharing your code.

    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.
    • 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.

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  3. Version published to 10.1101/2020.10.22.20217638v1 on medRxiv