Transmission of corona virus disease 2019 during the incubation period may lead to a quarantine loophole

  1. Wei Xia
  2. Jiaqiang Liao
  3. Chunhui Li
  4. Yuanyuan Li
  5. Xi Qian
  6. Xiaojie Sun
  7. Hongbo Xu
  8. Gaga Mahai
  9. Xin Zhao
  10. Lisha Shi
  11. Juan Liu
  12. Ling Yu
  13. Meng Wang
  14. Qianqian Wang
  15. Asmagvl Namat
  16. Ying Li
  17. Jingyu Qu
  18. Qi Liu
  19. Xiaofang Lin
  20. Shuting Cao
  21. Shu Huan
  22. Jiying Xiao
  23. Fengyu Ruan
  24. Hanjin Wang
  25. Qing Xu
  26. Xingjuan Ding
  27. Xingjie Fang
  28. Feng Qiu
  29. Jiaolong Ma
  30. Yu Zhang
  31. Aizhen Wang
  32. Yuling Xing
  33. Shunqing Xu

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Abstract

Background

The ongoing outbreak of novel corona virus disease 2019 (COVID-19) in Wuhan, China, is arousing international concern. This study evaluated whether and when the infected but asymptomatic cases during the incubation period could infect others.

Methods

We collected data on demographic characteristics, exposure history, and symptom onset day of the confirmed cases, which had been announced by the Chinese local authorities. We evaluated the potential of transmission during the incubation period in 50 infection clusters, including 124 cases. All the secondary cases had a history of contact with their first-generation cases prior to symptom onset.

Results

The estimated mean incubation period for COVID-19 was 4.9 days (95% confidence interval [CI], 4.4 to 5.4) days, ranging from 0.8 to 11.1 days (2.5th to 97.5th percentile). The observed mean and standard deviation (SD) of serial interval was 4.1±3.3 days, with the 2.5th and 97.5th percentiles at −1 and 13 days. The infectious curve showed that in 73.0% of the secondary cases, their date of getting infected was before symptom onset of the first-generation cases, particularly in the last three days of the incubation period.

Conclusions

The results indicated the transmission of COVID-9 occurs among close contacts during the incubation period, which may lead to a quarantine loophole. Strong and effective countermeasures should be implemented to prevent or mitigate asymptomatic transmission during the incubation period in populations at high risk.

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  1. ScreenIT

    SciScore for 10.1101/2020.03.06.20031955: (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:
    Nevertheless, there are some limitations in this study. The data about virus detection were not available for those asymptomatic persons in their incubation period. Since the follow-up quantitative reverse-transcriptase-polymerase-chain-reaction (qRT-PCR) of virus nucleic acid assay was not available for most close contacts currently in China, it is difficult to obtain evidence of molecular biological monitoring in a short time. If qRT-PCR assays are performed for a group of close contacts, more convincing evidence will be provided for transmission of COVID-19 during the incubation period. In conclusion, the COVID-19 cases in the incubation period are potential infection sources, especially within three days prior to the symptom onset. It is imperative to trace back the close contacts of confirmed cases before the symptom onset and avoid the quarantine loopholes.

    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 10.1101/2020.03.06.20031955 on medRxiv