[M T]

the latest from the CDC and NIH on the case fatality rate, articles published today in the New England J of Medicine: free NEJM article

On the basis of a case definition requiring a diagnosis of pneumonia, the currently reported case fatality rate is approximately 2%. In another article in the Journal, Guan et al. report mortality of 1.4% among 1099 patients with laboratory-confirmed Covid-19; these patients had a wide spectrum of disease severity. If one assumes that the number of asymptomatic or minimally symptomatic cases is several times as high as the number of reported cases, the case fatality rate may be considerably less than 1%. This suggests that the overall clinical consequences of Covid-19 may ultimately be more akin to those of a severe seasonal influenza (which has a case fatality rate of approximately 0.1%) or a pandemic influenza (similar to those in 1957 and 1968) rather than a disease similar to SARS or MERS, which have had case fatality rates of 9 to 10% and 36%, respectively.

Am I missing something?  I see no suggestion of any basis for that assumption mentioned in this editorial.  The assumption could be that there are 1000x or 0.001x asymptomatic cases as confirmed cases, as far as I can tell.  So I don't understand how they can then say "This suggests...".

Had the authors said, "Based on experience with .... viruses, one might suspect <assumption>", then that at least is based on something.

---

Btw, another bit of evidence, in my opinion, that mildly symptomatic cases were being found in China is described in this Feb. 28 article about a Feb 28 NEJM article (reference 5 in the above NEJM editorial)

Most of an 1,100-patient cohort (with laboratory-confirmed COVID-19 in 552 hospitals in 30 Chinese provinces through Jan. 29) hospitalized in China for COVID-19 did not initially have fever, and many had no radiologic abnormalities....
Cough was the most common symptom, with over two-thirds presenting with cough upon admission.
Interestingly, only about 40% presented with fever, though nearly all developed fever while hospitalized....
Researchers reported a median incubation period of 4 days.
While ground-glass opacity was the most common finding on chest CT imaging, they added that in 18% of non-severe cases, no radiographic or CT abnormality was found.
Patients stayed in the hospital for a median of 12 days, during which time most received a diagnosis of pneumonia.
Incubation period could only be estimated in 291 patients with documented information.
Also, it was restricted to patients admitted to hospitals and therefore shed no light on characteristics or prevalence of less severe disease for which patients received outpatient care or none at all.

One third admitted to the hospital did not have a cough.
60% admitted to the hospital did not have a fever.
This cohort, however they were chosen, only included hospital patients with confirmed COVID-19.
I'm curious what was necessary for them to be admitted. 
Had they already tested positive?  If so, what was necessary or sufficient for them to be tested?

Apparently, many of these patients got into the hospitals very early in the disease, before their symptoms fully developed.  Presumably that gave them a better chance for a favorable outcome.

[M T]

the latest from the CDC and NIH on the case fatality rate, articles published today in the New England J of Medicine: free NEJM article

On the basis of a case definition requiring a diagnosis of pneumonia, the currently reported case fatality rate is approximately 2%. In another article in the Journal, Guan et al. report mortality of 1.4% among 1099 patients with laboratory-confirmed Covid-19; these patients had a wide spectrum of disease severity. If one assumes that the number of asymptomatic or minimally symptomatic cases is several times as high as the number of reported cases, the case fatality rate may be considerably less than 1%. This suggests that the overall clinical consequences of Covid-19 may ultimately be more akin to those of a severe seasonal influenza (which has a case fatality rate of approximately 0.1%) or a pandemic influenza (similar to those in 1957 and 1968) rather than a disease similar to SARS or MERS, which have had case fatality rates of 9 to 10% and 36%, respectively.

Am I missing something?  I see no suggestion of any basis for that assumption mentioned in this editorial.  The assumption could be that there are 1000x or 0.001x asymptomatic cases as confirmed cases, as far as I can tell.  So I don't understand how they can then say "This suggests...".

Had the authors said, "Based on experience with .... viruses, one might suspect <assumption>", then that at least is based on something.

---

Btw, another bit of evidence, in my opinion, that mildly symptomatic cases were being found in China is described in this Feb. 28 article about a Feb 28 NEJM article (reference 5 in the above NEJM editorial)

Most of an 1,100-patient cohort (with laboratory-confirmed COVID-19 in 552 hospitals in 30 Chinese provinces through Jan. 29) hospitalized in China for COVID-19 did not initially have fever, and many had no radiologic abnormalities....
Cough was the most common symptom, with over two-thirds presenting with cough upon admission.
Interestingly, only about 40% presented with fever, though nearly all developed fever while hospitalized....
Researchers reported a median incubation period of 4 days.
While ground-glass opacity was the most common finding on chest CT imaging, they added that in 18% of non-severe cases, no radiographic or CT abnormality was found.
Patients stayed in the hospital for a median of 12 days, during which time most received a diagnosis of pneumonia.
Incubation period could only be estimated in 291 patients with documented information.
Also, it was restricted to patients admitted to hospitals and therefore shed no light on characteristics or prevalence of less severe disease for which patients received outpatient care or none at all.

One third admitted to the hospital did not have a cough.
60% admitted to the hospital did not have a fever.
This cohort, however they were chosen, only included hospital patients with confirmed COVID-19.
I'm curious what was necessary for them to be admitted. 
Had they already tested positive?  If so, what was necessary or sufficient for them to be tested?

Apparently, many of these patients got into the hospitals very early in the disease, before their symptoms fully developed.  Presumably that gave them a better chance for a favorable outcome.