The fomite contribution to the transmission of COVID-19 in the UK: an evolutionary population estimate

  1. A. Meiksin

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Abstract

A SEIR model with an added fomite term is used to constrain the contribution of fomites to the spread of COVID-19 under the Spring 2020 lockdown in the UK. Assuming uniform priors on the reproduction number in lockdown and the fomite transmission rate, an upper limit is found on the fomite transmission rate of less than 1 contaminated object in 7 per day per infectious person (95% CL). Basing the prior on the reproduction rate during lockdown instead on the CoMix study results for the reduction in social contacts under lockdown, and assuming the reproduction number scales with the number of social contacts, provides a much more restrictive upper limit on the transmission rate by contaminated objects of fewer than 1 in 30 per day per infectious person (95% CL). Applied to postal deliveries and groceries, the upper limit on the fomite transmission rate corresponds to a probability below 1 in 70 (95% CL) that a contaminated object transmits the infection. Fewer than about half (95% CL) of the total number of deaths during the lockdown are found to arise from fomites, and most likely fewer than a quarter. These findings apply only to fomites with a transmission rate that is unaffected by a lockdown.

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  1. ScreenIT

    SciScore for 10.1101/2021.08.11.21261903: (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

    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:
    Limitations of study: Placing constraints on the contribution of fomites during lockdown requires some key assumptions. In this context, fomites may be divided into two types, those that scale like the number of social contacts and those independent of the number of social contacts. Only the latter, such as fomites arising from essential services that continued through the lockdown like post deliveries and food and medicine purchases, may be constrained using the change in the evolution of the population statistics following lockdown. Fomite transmission rates that scale with the number of social contacts, such as may occur for fomites in office spaces, likely scale with the reproduction number for direct transmission, and so their effects on population evolution statistics are indistinguishable from those of direct transmission. It is not possible to rule out from population statistics the possibility that most of the transmission prior to lockdown arose from workplace fomites. Although contamination through household fomites may have then been expected to increase during lockdown, an increase in fomite transmission in a domestic setting may have been masked by the limited number of additional family members that could have been infected. Increased hand-washing in the home could in principle also be a factor. The strongest constraints on fomite transmission in this study rely on the measured change in the number of social contacts following lockdown from the CoMix study in t...

    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.

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  2. Version published to 10.1101/2021.08.11.21261903v1 on medRxiv