Maryn McKenna: The New Coronavirus: More Cases, More Deaths, Unclear Transmission

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http://www.wired.com/wiredscience/20...onavirus-four/

The New Coronavirus: More Cases, More Deaths, Unclear Transmission
By Maryn McKenna12.13.12 8:30 AM

There’s lots of news to catch up with regarding the new coronavirus that emerged last summer in the Middle East and has been causing concern to international health authorities all autumn: additional cases, additional deaths, and new lab evidence that is more than a little concerning.


First: The case count has now risen from six to nine. One of those cases, we knew about already; it is the remaining person in the Saudi family cluster announced last month, whose case analysis was pending. But the other two are newly uncovered, and interesting: They are from a group of 11 health care workers and patients who fell ill in Jordan back in April. A correspondent to the mailing list ProMED actually raised a question about this cluster when the first known cases were disclosed. At the time, the cases were ruled to be not caused by coronavirus — but as the new virus had not yet been recognized, the test used was for known coronaviruses. The victims were negative on that test, but positive when a retest on their stored samples, using the new assay, was done recently.

Sadly, all three of these new cases died — so not only has the case count risen, but the fatality count has also, to 5 out of 9. Though we have only a few cases, that is still a case-fatality rate of more than 50 percent. By contrast, the case-fatality rate of SARS, the last novel coronavirus to trouble public health, was less than 10 percent.

more at above link...

[Giuseppe Michieli]

It is impossible to calculate case-fatality rate if the actual number of cases (asymptomatic, mild, severe and fatal) is unknown.

Again, drawing conclusion before the picture is revealed may cause later damage to international health agencies reputation and credibility.

(IOH)

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It is important to remember that there are multiple factors that can cause the apparent CFR of a disease to differ from its true fatality ratio. McKenna correctly mentions in the article that missed mild cases would artifically inflate the apparent CFR making the inital reports seem more severe than they really are. H1N1 was a good example of this overestimate.

It is often forgotten, though, that the apparent CFR of SARS actually rose as the outbreak progressed, not dropped. Some of this was the result of previous reported cases dying (which has not happened yet this time - all cases reported as alive have recovered, perhaps due to the longer time needed to confirm cases). Some of this was also due to the accidental inclusion of non-SARS (and thus milder) illnesses in the inital numbers. Remember that mainland China "officially" had a 6% CFR for SARS for the entire outbreak (after reporting <2% CFR though March 2003), whereas Toronto and Hong Kong, with presumably better care, had closer to a 18% CFR.

So it is way too early to estimate the CFR of this novel virus.