For example, on the clinical course of the disease, it has this: https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-guidance-management-patients.html#clinical-course - “Clinical presentation among reported cases of COVID-19 varies in severity from asymptomatic infection to mild illness to severe or fatal illness. Some reports suggest the potential for clinical deterioration during the second week of illness.[2,5] In one report, among patients with confirmed COVID-19 and pneumonia, just over half of patients developed dyspnea a median of 8 days after illness onset (range: 5–13 days). [2] In another report, the mean time from illness onset to hospital admission with pneumonia was 9 days.[1] Acute respiratory distress syndrome (ARDS) developed in 17–29% of hospitalized patients, and secondary infection developed in 10%. [2,4] In one report, the median time from symptom onset to ARDS was 8 days.[3]”
For information about when someone is infectious, https://www.cdc.gov/coronavirus/2019-ncov/hcp/faq.html, it says, “The onset and duration of viral shedding and period of infectiousness for COVID-19 are not yet known. It is possible that SARS-CoV-2 RNA may be detectable in the upper or lower respiratory tract for weeks after illness onset, similar to infection with MERS-CoV and SARS-CoV. However, detection of viral RNA does not necessarily mean that infectious virus is present. Asymptomatic infection with SARS-CoV-2 has been reported, but it is not yet known what role asymptomatic infection plays in transmission. Similarly, the role of pre-symptomatic transmission (infection detection during the incubation period prior to illness onset) is unknown. Existing literature regarding SARS-CoV-2 and other coronaviruses (e.g. MERS-CoV, SARS-CoV) suggest that the incubation period may range from 2–14 days.”
I found this slightly hard to parse (for the reasons I find academic papers generally hard to parse), and have re-written it here to be slightly easier for me:
Clinical presentation among reported cases of COVID-19 varies in severity from asymptomatic infection to mild illness to severe or fatal illness.
Some reports suggest the potential for clinical deterioration during the second week of illness. In one report, among patients with confirmed COVID-19 and pneumonia, just over half of patients developed dyspnea a median of 8 days after illness onset (range: 5–13 days).
In another report, the mean time from illness onset to hospital admission with pneumonia was 9 days. Acute respiratory distress syndrome (ARDS) developed in 17–29% of hospitalized patients, and secondary infection developed in 10%. In one report, the median time from symptom onset to ARDS was 8 days.
The onset and duration of viral shedding and period of infectiousness for COVID-19 are not yet known.
It is possible that SARS-CoV-2 RNA may be detectable in the upper or lower respiratory tract for weeks after illness onset, similar to infection with MERS-CoV and SARS-CoV. However, detection of viral RNA does not necessarily mean that infectious virus is present.
Asymptomatic infection with SARS-CoV-2 has been reported, but it is not yet known what role asymptomatic infection plays in transmission. Similarly, the role of pre-symptomatic transmission (infection detection during the incubation period prior to illness onset) is unknown. Existing literature regarding SARS-CoV-2 and other coronaviruses (e.g. MERS-CoV, SARS-CoV) suggest that the incubation period may range from 2–14 days.
I don’t see where the second- and third-to-last links contain information on contagiousness. To make sure I’m not missing something:
the section under “when someone is infectious” says “The onset and duration of viral shedding and period of infectiousness for COVID-19 are not yet known”
For anyone just tuning in, David Manheim and I have a pre-existing dispute over the usefulness of CDC-given information. I’m going to leave this up because others might find it useful, and I’m not going to respond directly because there’s no reason to expect it to go differently than the last 5 times we discussed the CDC, but I do think he’s wrong.
If you are asking about the R_0, there is a lot of information that you’re mentioned elsewhere. If you’re asking about infectiousness time periods, CDC has information that you just cited. You’re looking for numerical epidemiological estimates—and the papers on the epidemiology that CDC cites are very clear that they don’t have that good data. Do you want a proxy for modeling purposes? Feel free to use any of the guesses provided in the literature so far, but note that most places where data might have existed that could inform this are locked down, so there would be fairly little data to indicate if now-formerly infected people are still transmitting the disease.
So you’re asking for information that experts say is currently unknown. That means any supposed “answers” to how long the infectiousness period lasts that have been published so far are going to be misleading. And knowing that a clear answer doesn’t exist is valuable information—it means you can stop sources like businessinsider stating that on average after 17 days people who recover are released from the hospital—which may be a correct average, but as the CDC’s explanation about the need for testing viral load in individual cases before release from in-home isolation makes clear, tells you nothing about how long they remain infectious.
The CDC has a lot of useful information about much of this: https://www.cdc.gov/coronavirus/2019-ncov/about/index.html
For example, on the clinical course of the disease, it has this: https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-guidance-management-patients.html#clinical-course - “Clinical presentation among reported cases of COVID-19 varies in severity from asymptomatic infection to mild illness to severe or fatal illness. Some reports suggest the potential for clinical deterioration during the second week of illness.[2,5] In one report, among patients with confirmed COVID-19 and pneumonia, just over half of patients developed dyspnea a median of 8 days after illness onset (range: 5–13 days). [2] In another report, the mean time from illness onset to hospital admission with pneumonia was 9 days.[1] Acute respiratory distress syndrome (ARDS) developed in 17–29% of hospitalized patients, and secondary infection developed in 10%. [2,4] In one report, the median time from symptom onset to ARDS was 8 days.[3]”
For information about when someone is infectious, https://www.cdc.gov/coronavirus/2019-ncov/hcp/faq.html, it says, “The onset and duration of viral shedding and period of infectiousness for COVID-19 are not yet known. It is possible that SARS-CoV-2 RNA may be detectable in the upper or lower respiratory tract for weeks after illness onset, similar to infection with MERS-CoV and SARS-CoV. However, detection of viral RNA does not necessarily mean that infectious virus is present. Asymptomatic infection with SARS-CoV-2 has been reported, but it is not yet known what role asymptomatic infection plays in transmission. Similarly, the role of pre-symptomatic transmission (infection detection during the incubation period prior to illness onset) is unknown. Existing literature regarding SARS-CoV-2 and other coronaviruses (e.g. MERS-CoV, SARS-CoV) suggest that the incubation period may range from 2–14 days.”
For information about how to tell when someone is no longer infectious, see: https://www.cdc.gov/coronavirus/2019-ncov/hcp/disposition-hospitalized-patients.html
They also have a frequently updated list of papers that have the sources for their information: https://www.cdc.gov/coronavirus/2019-ncov/publications.html
Thanks!
I found this slightly hard to parse (for the reasons I find academic papers generally hard to parse), and have re-written it here to be slightly easier for me:
For example, on the clinical course of the disease, it has this: https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-guidance-management-patients.html#clinical-course
For information about when someone is infectious, https://www.cdc.gov/coronavirus/2019-ncov/hcp/faq.html, it says
I don’t see where the second- and third-to-last links contain information on contagiousness. To make sure I’m not missing something:
the section under “when someone is infectious” says “The onset and duration of viral shedding and period of infectiousness for COVID-19 are not yet known”
Interim Guidance for Discontinuation of Transmission-Based Precautions and Disposition of Hospitalized Patients with COVID-19 contains considerations, but not instructions, for when to discontinue isolation, and nothing directly on when people are not contagious.
Am I missing something?
For anyone just tuning in, David Manheim and I have a pre-existing dispute over the usefulness of CDC-given information. I’m going to leave this up because others might find it useful, and I’m not going to respond directly because there’s no reason to expect it to go differently than the last 5 times we discussed the CDC, but I do think he’s wrong.
If you are asking about the R_0, there is a lot of information that you’re mentioned elsewhere. If you’re asking about infectiousness time periods, CDC has information that you just cited. You’re looking for numerical epidemiological estimates—and the papers on the epidemiology that CDC cites are very clear that they don’t have that good data. Do you want a proxy for modeling purposes? Feel free to use any of the guesses provided in the literature so far, but note that most places where data might have existed that could inform this are locked down, so there would be fairly little data to indicate if now-formerly infected people are still transmitting the disease.
So you’re asking for information that experts say is currently unknown. That means any supposed “answers” to how long the infectiousness period lasts that have been published so far are going to be misleading. And knowing that a clear answer doesn’t exist is valuable information—it means you can stop sources like businessinsider stating that on average after 17 days people who recover are released from the hospital—which may be a correct average, but as the CDC’s explanation about the need for testing viral load in individual cases before release from in-home isolation makes clear, tells you nothing about how long they remain infectious.