Thread by @jeremyfaust

The WHO says that asymptomatic transmission is “very rare.”

That’s the headline.

Is that what @mvankerkhove is saying?

No, I do not think so.

Some thoughts in a brief 🧵

cnbc.com/2020/06/08/asy… cc @jrovner @thehowie @MDaware @hmkyale @BillGates @AllisonRhines

What Dr. Van Kerkhove is really saying, I think, is that when WHO follows up with people who did contact tracing, they found that they could *not detect* a lot of asymptomatic spread of SARS-CoV-2.

How do we square that with articles like this? acpjournals.org/doi/10.7326/M2…

Answer:

Whether this is what was meant or not, this is a comment that summarizes the ability of CONTACT TRACING to *find* asymptomatic spread. Not to quantify if it does.

It does! We’ve lots of evidence that the virus spreads asymptomatically (see above).

Superspreaders, for example.

The correct conclusion is NOT that the WHO has evidence that SARS-CoV-2 is not commonly spread asymptomatically. That’s possibly rather wrong.

The correct interpretation is more likely that CONTACT TRACING is woefully inadequate at finding asymptomatic spread.

That’s different!

Asymptomatic spread, in my opinion, is the reason WHY we have a pandemic.

The usual playbook—which is great for symptomatic disease tracking—has saved millions of lives over the years in the hands of groups like WHO.

But this damn virus “exploits” a weakness in our playbook.

We’ve rarely/never before dealt with asymptomatic spread in a respiratory virus that has such an short course like this.

We’ve seen it in HIV.

If a person with undiagnosed HIV feels fine for months, there’s no way contact tracing works if they have had many partners.

So the correct statement is: “We are finding that contact tracing is inadequate to the task at hand. It is important for tracking symptomatic disease. But testing asymptomatic high risk workers is the only way to try to detect that subset which we can’t otherwise detect.”

/fin.