An Estimation of Reproduction Number of SARS-CoV-2 by Age Class for Age Classes in Japan

  1. Junko Kurita
  2. Takahide Hata
  3. Tamie Sugawara
  4. Yasushi Ohkusa
  5. Atsuko Hata

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Abstract

Background

Infectiousness of COVID-19 by age class inferred from the infection source and by infected people might be different. However, studies of such infectiousness have not been reported.

Object

The object of this study was estimation of reproduction numbers by age class of the source of infection and the infected persons. To do so, after examining a new procedure for reproduction number estimation, we checked infected places by age class of the source of infection and the infected persons.

Method

We ignore patients who infected no one because their reliability might be lower than that of patients who infected more than one person. We estimated the reproduction number from the histogram of the number of the infected people by the same patient, assuming that the histogram follows an exponential distribution.

Discussion and Conclusion

The obtained results demonstrated that the effective reproduction numbers for infection from children were very low. They were higher among adult and elderly people than among the same age class. Moreover, although the highest and second-highest infected places were ‘other’ and ‘at home’ with some exceptions, the data for infection at hospitals were remarkable among adults and elderly people. Among elderly people, infection at facilities for elderly was also high. Infections at nursing schools, schools, restaurants, and entertainment venues at night were negligible.

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  1. ScreenIT

    SciScore for 10.1101/2021.01.14.21249854: (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:
    The present study has some limitations. First, we used data that were limited to those for which the infection source was identified, with the age class of the infected persons reported, and infected people all with some symptoms. However, those symptomatic patients examined for the present study were very rare among all symptomatic patients. Sources of infection for most of patients were unknown and might not be reported in public even after being identified by the public health center. Therefore, we assumed implicitly that they were representable in all symptomatic patients. The data validity should be confirmed. Second, similar to the first point, we limited analysis to symptomatic patients because all asymptomatic patients were not reported as symptomatic patients. We also implicitly assumed that asymptomatic patients and symptomatic patients were the same in terms of infectiousness. Therefore, we must check that point. Thirdly, our proposed and used estimation procedure for the effective reproduction number might be experimental. Its robustness should be examined as the next challenge for future research. Fourthly, the source of infection and infected place were identified through contact tracing by the public health center. It was not based on the lineage of the genetic sequence of SARS-CoV-2 or other method. Therefore, we must remark that this information might include some ambiguity.

    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.

    About SciScore

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  2. Version published to 10.1101/2021.01.14.21249854 on medRxiv