Coronavirus disease (COVID-19): Summary of assumptions

Updated: April 13, 2020

In order to develop technical guidance to support F/P/T public health authorities and front-line clinicians in health care settings responding to the novel coronavirus causing COVID-19, a number of assumptions were taken to develop interim guidance documents. These assumptions are based on currently available scientific evidence and expert opinion and are subject to change as new information on transmissibility and epidemiology becomes available.

Table of contents

Transmission

Incubation period

Risk:

In the absence of infection prevention and control precautions, including the consistent and appropriate use of personal protective equipment:

Period of communicability

The period of communicability is not well understood. Detailed information from people infected is needed to characterize onset and duration of viral shedding and determine the infectious period of COVID-19.

Contamination of surfaces

Reference documents:

Centers for Disease Control and Prevention (CDC). CDC Frequently Asked Questions and Answers. 19 March 2020. Available from: https://www.cdc.gov/coronavirus/2019-ncov/faq.html

European Centre for Disease Prevention and Control (ECDC). Q & A on COVID-19. 6 Mar 2020. Available at: https://www.ecdc.europa.eu/en/novel-coronavirus-china/questions-answers

Kampf G, Todt D, Pfaender S, Steinmann E. Persistence of coronaviruses on inanimate surfaces and its inactivation with biocidal agents. Journal of Hospital Infections. 2020 March; 104(3): 246-51.

WHO EPI-WiN presentation deck. More information about COVID-19 public health implications.

World Health Organization (WHO). Advice on the use of masks in the community, during home care and in health care settings in the context of the novel coronavirus (2019-nCoV) outbreak. 19 March 2020. Available from: https://www.who.int/publications-detail/advice-on-the-use-of-masks-the-community-during-home-care-and-in-health-care-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak

World Health Organization (WHO). WHO Q&A on coronaviruses. 9 March 2020. Available from: https://www.who.int/news-room/q-a-detail/q-a-coronaviruses

World Health Organization (WHO). WHO Q&A on infection prevention and control for health care workers caring for patients with suspected or confirmed 2019-nCoV. 1 March 2020. Available from: https://www.who.int/news-room/q-a-detail/q-a-on-infection-prevention-and-control-for-health-care-workers-caring-for-patients-with-suspected-or-confirmed-2019-ncov

World Health Organization (WHO). WHO recommendations to reduce risk of transmission of emerging pathogens from animals to humans in live animal marks. 2020. Available at: https://www.who.int/health-topics/coronavirus/who-recommendations-to-reduce-risk-of-transmission-of-emerging-pathogens-from-animals-to-humans-in-live-animal-markets

World Health Organization (WHO). WHO Clinical management of severe acute respiratory infection when novel coronavirus (2019-nCoV) infection is suspected: Interim guidance. 13 March 2020. Available at: https://www.who.int/publications-detail/clinical-management-of-severe-acute-respiratory-infection-when-novel-coronavirus-(ncov)-infection-is-suspected

World Health Organization (WHO). Coronavirus disease 2019 (COVID-19) Situation Report - 30. Data as reported by 19 February 2020. Available at: https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200219-sitrep-30-covid-19.pdf?sfvrsn=3346b04f_2

Zhang E, Du RH, Li B, Zheng XS, Yang XL, Hu B, Wang YY, Xiao GF, Yan B, Shi ZL, Zhou P. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Emerging Microbes & Infections. 2020 Feb; 9: 386-89.

Endnotes

Footnote 1

WHO. Q&A on coronaviruses. [Online] 9 March 2020 [Accessed at: https://www.who.int/news-room/q-a-detail/q-a-coronaviruses].

Return to footnote 1 referrer

Footnote 2

He X, Lau EH, Wu P. et al. Temporal dynamics in viral shedding and transmissibility of COVID-19. medRxiv preprint. 18 Mar 2020 [Accessed at: https://www.medrxiv.org/content/10.1101/2020.03.15.20036707v2]

Return to footnote 2 referrer

Footnote 3

Xia, W., Liao, J., Li, C. et al. Transmission of corona virus disease 2019 during the incubation period may lead to a quarantine loophole. medRxiv preprint. 8 Mar 2020 [Accessed at: https://www.medrxiv.org/content/10.1101/2020.03.06.20031955v1]

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Footnote 4

Rothe, C., Schunk, M., Sothmann, P. et al. Transmission of 2019-nCoV infection from an asymptomatic contact in Germany. The New England Journal of Medicine. 5 Mar 2020 [Accessed at: https://www.nejm.org/doi/full/10.1056/NEJMc2001468]

Return to footnote 4 referrer

Footnote 5

Yu, P., Zhu, J., Zhang, Z. et al. A familial cluster of infection associated with the 2019 novel coronavirus indicating potential person-to-person transmission during the incubation period. The Journal of Infectious Diseases. 18 Feb 2020 [Accessed at: https://www.ncbi.nlm.nih.gov/pubmed/32067043]

Return to footnote 5 referrer

Footnote 6

Bai, Y., Yao, L., Wei, T. et al. Presumed asymptomatic carrier transmission of COVID-19. JAMA. 21 Feb 2020 [Accessed at: https://jamanetwork.com/journals/jama/fullarticle/2762028]

Return to footnote 6 referrer

Footnote 7

Hu, Z., Song, C., Xu, C. et al. Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, china. medRxiv preprint. 25 Feb 2020 [Accessed at: https://www.medrxiv.org/content/10.1101/2020.02.20.20025619v2]

Return to footnote 7 referrer

Footnote 8

Tong, Z., Tang, A., Li, K. et al. Potential presymptomatic transmission of SARS-CoV-2, Zhejiang province, China, 2020. Emerging Infectious Diseases [Accessed at: https://www.ncbi.nlm.nih.gov/pubmed/32091386]

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Footnote 9

Wang, P., Lian, Z., Chen, Y. et al. Investigation of a cluster of 2019 novel coronavirus disease (COVID-19) with possible transmission during the incubation period - Shenyang City, China, 2020. China CDC Weekly, 2(8), 126.

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Footnote 10

Tang, A., Tong, Z., Wang, H. et al. Detection of novel coronavirus by RT-PCR in stool specimen from asymptomatic child, China. Emerging Infectious Diseases [Accessed at: https://www.ncbi.nlm.nih.gov/pubmed/32150527]

Return to footnote 10 referrer

Footnote 11

Covid-19 National Emergency Response Center, Epidemiology, Case Management Team, Korea Centers for Disease Control, & Prevention. Early epidemiological and clinical characteristics of 28 cases of coronavirus disease in South Korea. Osong Public Health and Research Perspectives [Accessed at: https://ophrp.org/journal/view.php?doi=10.24171/j.phrp.2020.11.1.03

Return to footnote 11 referrer

Footnote 12

Lu, S., Lin, J., Zhang, Z. et al. Alert for non-respiratory symptoms of coronavirus disease 2019 (COVID-19) patients in epidemic period: A case report of familial cluster with three asymptomatic COVID-19 patients. Journal of Medical Virology. 19 Mar 2020 [Accessed at: https://onlinelibrary.wiley.com/doi/abs/10.1002/jmv.25776]

Return to footnote 12 referrer

Footnote 13

Lui, X., Wu, J., Lui, M. et al. Presymptomatic transmission of COVID-19 in a cluster of cases occurred in confined space: A case report. 19 Mar 2020 [Accessed at: https://www.researchsquare.com/article/rs-18053/v1]

Return to footnote 13 referrer

Footnote 14

Li, P., Fu, J. B., Li, K. F. et al. Transmission of COVID-19 in the terminal stage of incubation period: A familial cluster. International Journal of Infectious Diseases. [Accessed at: https://www.ncbi.nlm.nih.gov/pubmed/32194239]

Return to footnote 14 referrer

Footnote 15

Qian, G., Yang, N., Ma, A. H. Y. et al. A COVID-19 transmission within a family cluster by presymptomatic infectors in china. Clinical Infectious Diseases. [Accessed at: https://www.ncbi.nlm.nih.gov/pubmed/32201889]

Return to footnote 15 referrer

Footnote 16

Kimball A., Hatfield K.M., Arons M. et al. Asymptomatic and presymptomatic SARS-CoV-2 infections in residents of a long-term care skilled nursing facility - King County, Washington, March 2020. MMWR Morb Mortal Wkly Rep. 27 Mar 2020 [Accessed at: https://www.cdc.gov/mmwr/volumes/69/wr/mm6913e1.htm?s_cid=mm6913e1_&deliveryName=USCDC_921-DM24113]

Return to footnote 16 referrer

Footnote 17

Mizumoto K., Kagaya K., Zarebski A., Chowell G. Estimating the asymptomatic proportion of coronavirus disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship, Yokohama, Japan, 2020. Euro Surveill.[Accessed at: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.10.2000180]

Return to footnote 17 referrer

Footnote 18

Wölfel, R., Corman, V.M., Guggemos, W. et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 1 April 2020 [Accessed at: https://www.nature.com/articles/s41586-020-2196-x]

Return to footnote 18 referrer

Footnote 19

Wei W.E., Li Z., Chiew C.J. et al. Presymptomatic Transmission of SARS-CoV-2 - Singapore, January 23-March 16, 2020. MMWR Morb Mortal Wkly Rep. 1 April 2020. [Accessed at: https://www.cdc.gov/mmwr/volumes/69/wr/mm6914e1.htm#suggestedcitation]

Return to footnote 19 referrer

Footnote 20

Kluytmans, M., Buiting, A., Pas, S.et al. SARS-CoV-2 infection in 86 healthcare workers in two dutch hospitals in March 2020. medRxiv preprint. 31 Mar 2020 [Accessed at: https://www.medrxiv.org/content/10.1101/2020.03.23.20041913v3]

Return to footnote 20 referrer

Footnote 21

Gostic, K., Gomez, A. C., Mummah, R. O. et al. Estimated effectiveness of symptom and risk screening to prevent the spread of COVID-19. eLife. 24 Feb 2020 [Accessed at: https://elifesciences.org/articles/55570]

Return to footnote 21 referrer

Footnote 22

Nishiura H., Kobayashi T., Suzuki A. et al. Estimation of the asymptomatic ratio of novel coronavirus infections (COVID-19). International Journal of Infectious Diseases. 13 Feb 2020. https://www.ijidonline.com/article/S1201-9712(20)30139-9/pdf]

Return to footnote 22 referrer

Footnote 23

Chan, J. F., Yuan, S., Kok, K. H.et al. A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: A study of a family cluster. Lancet. [Accessed at: https://www.ncbi.nlm.nih.gov/pubmed/31986261]

Return to footnote 23 referrer

Footnote 24

Zhang, W., Du, R. Li, B. et al. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Journal of Emerging Microbes & Infections. [Accessed at: https://www.tandfonline.com/doi/full/10.1080/22221751.2020.1729071]

Return to footnote 24 referrer

Footnote 25

CDC. Frequently Asked Questions and Answers. [Online] 19 March 2020 [Accessed at https://www.cdc.gov/coronavirus/2019-ncov/faq.html]

Return to footnote 25 referrer

Footnote 26

WHO. Q&A on infection prevention and control for health care workers caring for patients with suspected or confirmed 2019-nCoV. [Online] 1 March 2020 [Accessed at: https://www.who.int/news-room/q-a-detail/q-a-on-infection-prevention-and-control-for-health-care-workers-caring-for-patients-with-suspected-or-confirmed-2019-ncov].

Return to footnote 26 referrer

Footnote 27

Ibid.

Return to footnote 27 referrer

Footnote 28

Ibid.

Return to footnote 28 referrer

Footnote 29

Zhang, W., Du, R. Li, B. et al. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Journal of Emerging Microbes & Infections. [Accessed at: https://www.tandfonline.com/doi/full/10.1080/22221751.2020.1729071]

Return to footnote 29 referrer

Footnote 30

WHO. WHO recommendations to reduce risk of transmission of emerging pathogens from animals to humans in live animal marks. [Online] February 13, 2020 [Accessed at: https://www.who.int/health-topics/coronavirus/who-recommendations-to-reduce-risk-of-transmission-of-emerging-pathogens-from-animals-to-humans-in-live-animal-markets].

Return to footnote 30 referrer

Footnote 31

OiE World Organisation for Animal Health. Questions and Answers on the 2019 Coronavirus Disease (COVID-19). [Online]. March 26, 2020 [Accessed at: https://www.oie.int/en/scientific-expertise/specific-information-and-recommendations/questions-and-answers-on-2019novel-coronavirus/].

Return to footnote 31 referrer

Footnote 32

Rothe, C., Schunk, M., Sothmann, P. et al. Transmission of 2019-nCoV infection from an asymptomatic contact in Germany. The New England Journal of Medicine. 5 Mar 2020 [Accessed at: https://www.nejm.org/doi/full/10.1056/NEJMc2001468]

Return to footnote 32 referrer

Footnote 33

Zhang, W., Du, R. Li, B. et al. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Journal of Emerging Microbes & Infections. [Accessed at: https://www.tandfonline.com/doi/full/10.1080/22221751.2020.1729071]

Return to footnote 33 referrer

Footnote 34

WHO. Coronavirus disease 2019 (COVID-19) Situation Report -59. [Online] 20 March 2020 [Accessed at https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200319-sitrep-59-covid-19.pdf?sfvrsn=c3dcdef9_2]

Return to footnote 34 referrer

Footnote 35

WHO. Advice on the use of masks in the community, during home care and in health care settings in the context of the novel coronavirus (2019-nCoV) outbreak. [Online] 21 February 2020 [Accessed at: https://www.who.int/publications-detail/advice-on-the-use-of-masks-the-community-during-home-care-and-in-health-care-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak]

Return to footnote 35 referrer

Footnote 36

Ibid.

Return to footnote 36 referrer

Footnote 37

Zhang, I., Wan, K., Chen, J. et al. When will the battle against coronavirus end in Wuhan: a SEIR modeling analysis. medRxiv preprint. 18 February 2020 [Accessed at: https://www.medrxiv.org/content/10.1101/2020.02.16.20023804v1].

Return to footnote 37 referrer

Footnote 38

Read, J., Bridgen, J.R., Cummings, D.A., Novel coronavirus 2019-CoV: early estimation of epidemiological parameters and epidemic predictions. 31 January 2020. [Accessed at: https://www.publichealthontario.ca/-/media/documents/ncov/research-medrxiv-epidemiological-parameters.pdf?la=en]

Return to footnote 38 referrer

Footnote 39

Lin, H. Liu, W. Gao, H., et al. Trends in transmissibility of 2019 novel coronavirus infected pneumonia in Wuhan and 29 provinces in China. 2 Mar 2020 [Accessed at: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3544821&utm_source=EC&utm_medium=Connect]

Return to footnote 39 referrer

Footnote 40

You, C., Deng, Y., Hu, W., et al Estimation of the time-varying reproduction number of COVID-19 outbreak in China. medRxiv preprint. 17 February 2020. [Accessed at: https://www.medrxiv.org/content/10.1101/2020.02.08.20021253v2]

Return to footnote 40 referrer

Footnote 41

Li, R., Pei, S., Chen., B., et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus. 16 Mar 2020. [Accessed at: https://science.sciencemag.org/content/early/2020/03/24/science.abb3221]

Return to footnote 41 referrer

Footnote 42

Ding, Y., Luo, S., Zheng, X., et al. Association of population migration and coronavirus disease 2019 epidemic control. medRxiv preprint. 20 February 2020. [Accessed at: https://www.medrxiv.org/content/10.1101/2020.02.18.20024661v1]

Return to footnote 42 referrer

Footnote 43

Hu, Z., Song, C., Xu, C., et al. Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China. 4 Mar 2020. [Accessed at: https://www.ncbi.nlm.nih.gov/pubmed/32146694]

Return to footnote 43 referrer

Footnote 44

Ding, Y., Luo, S., Zheng, X., et al. Association of population migration and coronavirus disease 2019 epidemic control. medRxiv preprint. 20 February 2020. [Accessed at: https://www.medrxiv.org/content/10.1101/2020.02.18.20024661v1]

Return to footnote 44 referrer

Footnote 45

Wölfel, R., Corman., V., Guggemos, W., et al. Virological assessment of hospitalized cases of coronavirus disease 2019. medRxiv preprint. 5 Mar 2020. [Accessed at: https://www.medrxiv.org/content/10.1101/2020.03.05.20030502v1.full.pdf]

Return to footnote 45 referrer

Footnote 46

WHO. Clinical management of severe acute respiratory infection when novel coronavirus (2019-nCoV) infection is suspected. [Online] 13 March 2020 [Accessed at: https://www.who.int/publications-detail/clinical-management-of-severe-acute-respiratory-infection-when-novel-coronavirus-(ncov)-infection-is-suspected].

Return to footnote 46 referrer

Footnote 47

WHO. Q&A on infection prevention and control for health care workers caring for patients with suspected or confirmed 2019-nCoV. [Online] 21 February 2020 [Accessed at: https://www.who.int/news-room/q-a-detail/q-a-on-infection-prevention-and-control-for-health-care-workers-caring-for-patients-with-suspected-or-confirmed-2019-ncov ].

Return to footnote 47 referrer

Footnote 48

van Doremalen N, Bushmaker T, Morris DH. et al. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. The New England Journal of Medicine. [Accessed at: https://www.nejm.org/doi/full/10.1056/NEJMc2004973]

Return to footnote 48 referrer

Footnote 49

WHO. Q&A on coronaviruses. [Online] 21 February 2020 [Accessed at: https://www.who.int/news-room/q-a-detail/q-a-coronaviruses].

Return to footnote 49 referrer

Footnote 50

Kampf G, Todt D, Pfaender S, Steinmann E, Persistence of coronaviruses on inanimate surfaces and its inactivation with biocidal agents, Journal of Hospital Infection.https://doi.org/10.1016/j.jhin.2020.01.022 [Accessed at: https://www.sciencedirect.com/science/article/pii/S0195670120300463?via%3Dihub].

Return to footnote 50 referrer

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