Monday, March 16, 2020

Avoid People Who Don't Have Symptoms. Uhhhhh ...

That makes things a bit more difficult, doesn't it?

I just read an article that makes the case that Infected people without symptoms might be driving the spread of coronavirus more than we realized. It's a longish article so I'll simply provide two excerpts that give a flavor for what's being learned. The studies cited are obviously from mainstream medical and scientific sources:

On Tuesday, Dr. Sandra Ciesek, director of the Institute of Medical Virology in Frankfurt, Germany, tested 24 passengers who had just flown in from Israel. 
Seven of the 24 passengers tested positive for coronavirus. Four of those had no symptoms, and Ciesek was surprised to find that the viral load of the specimens from the asymptomatic patients was higher than the viral load of the specimens from the three patients who did have symptoms.
Early, large-scale studies using mathematical modelling of outbreaks in Tianjin, China, and Singapore in January and February have also found significant amounts of spread by people who had not yet developed symptoms.
A study posted Sunday by Belgian and Dutch researchers shows that between 48% and 66% of the 91 people in the Singapore cluster contracted the infection from someone who was pre-symptomatic. Of the 135 people in the Tianjin cluster, between 62% and 77% caught it from someone was pre-symptomatic. 
One of the study's lead authors, Tapiwa Ganyani at the Data Science Institute at Hasselt University in Belgium, noted in an email to CNN that these are estimates with uncertainties.
Canadian, Dutch and Singaporean researchers looked at the same outbreaks in Tianjin and Singapore and found that infection was transmitted on average 2.55 days and 2.89 days before symptom onset respectively in each location. 
"Our analysis would suggest that presymptomatic transmission is pretty commonplace," said the study's lead author, Caroline Colijn, who leads the mathematics, genomics and prediction in infection and evolution research group at Simon Fraser University in British Columbia. 
CDC officials have said that while it's clear asymptomatic spread does happen, it does not appear to be the driver of the outbreak -- or as the CDC says on its website, asymptomatic transmission "is not thought to be the main way the virus spreads.
"If I were writing that CDC webpage today, I would phrase that a little more towards transmission before symptoms show up," Colijn said. 
Ciesek, the German virologist, agrees that the CDC should tweak its statement.
"I read it before, and I wondered to myself -- why are they so sure of this?" she said.


  1. Replies
    1. All we can really do is implement social distancing to the degree each of us is able and hope the public health authorities get a handle on this soon. Then, we need to implement social and economic distancing from China.

    2. Our options have always been limited. Our flatten the curve response makes epidemiological sense, in the near term, and up to a point. But in the long run, to steal a line, we're all dead.

      Our flatten the curve response is time limited. I'm hearing three weeks of social distancing. Fine. Three months of social distancing will collapse our economy, i.e., the operation will have succeeded, but the patient will be dead.

      The political element is starting to rattle and vibrate. Idiots in DC are taking about spending, spending! Spending what? America is bankrupt.

      At some pint in all this, the economic situation is going to have to take precedence--like it or not.

    3. "the economic situation is going to have to take precedence"

      But isn't that the fundamental problem? That to have a viable economy you need healthy people? It's a bit of a chicken/egg problem.

  2. Yeah, chicken and egg, but under drastic circumstances, incl. involving a not-so-healthy culture.
    Today Kunstler notes:

    "The foolish, idiotic identity politics ginned up by the Left, and their RACIALly-inflamed, SEXUALly-disturbed scribes in the Thinking Class, have successfully destroyed the last shred of an American COMMON culture, that held the country together through earlier vicissitudes.
    So, one concludes that we’ll be left stewing in poisonous tensions, and perhaps some violent conflicts, before those matters head toward some sort of resolution.

    Where does this all lead? Eventually, to a land and a people, who operate their society in a very different way, at a much more modest scale. The task of reorganizing our national life is immense. (There will be plenty to do, so don’t worry about that.)
    You can forget about the grandiose techno-narcissistic visions of electrified motoring, and a robotic nirvana of perpetual sex-crazed leisure.
    Everything we do has to be downscaled, from whatever manufacturing we can cobble back together, to rebuilding commercial ecosystems at a finer grain from region to region — in other words, what we now call *small business*, geared locally...."

    See .

    1. I certainly agree re the destruction of a common culture.

  3. It's interesting--but compared to what? Do we have the same level of detail and inventory when people contract the common cold or the flu?

    When you "catch" a cold or the flu, do you know who infected you?

    The German example above is about 24 people who were on an airplane together--that's not a normal setting on which to makes judgments about an entire population. I'm certainly not saying it's useless, but it's only somewhat different than the Wash State nursing home.

    A lot of this is just very partial information--and out of context regarding usable inputs.

    Were there only 24 on the plane?
    What about other passengers?
    What triggered the testing? Germans returning home> Israelis traveling to Germany? What? Random? Targeted?
    Are all flights being tested?
    Pre-existing conditions?
    What did their travel involve? (There seems to be lots of travel involved with infection vectors.)
    Outliers are always derived from small samples.

    I keep referring back to my Italian physician friend--most of the deaths are from very elderly and those with one or two pathologies. There are always exceptions to the general experience, but that does not make the exceptions to be the new rule.