Coronavirus

[ohmman]

I've seen a lot of discussion about herd immunity and getting lower risk people back into the economy (here and elsewhere). I mostly understand the argument from both its merits and negatives, but one thing I haven't read a lot about is how herd immunity is affected based on the longevity of personal immunity. That is, while I know we don't have data on this yet, I've heard that with other coronaviruses, immunity can only last 3-4 months. In a population where this thing is circulating on some kind of sliding time scale, what is the range of immunity duration that would allow herd immunity to actually take hold? From a lay perspective, it seems like it would have to be significantly longer than 3-4 months.

 

[EinSV]

Eventually, yes.
During the growth phase of the epidemic -- no

Again, I have to go with the experts on this, and they are saying we need antibody testing now.

The quote below is from Marc Lipsitch from the interview I posted earlier today. His IFR estimates tend to be on the high side compared to some, but he clearly recognizes the need for antibody testing to establish the infection rate -- in fact he says we "really, really need serologic studies":

Q. Could that number [proportion of the population that is immune] already be higher than we think?

A. One possibility is that there are just a huge number of undetected infections, many of which may produce immune responses. We may just have more “herd immunity” than we know. There are anecdotal hints about that, but no firm data yet. The flip side of it is that if some significant proportion of those infected don't get immune, then that subtracts from the immune fraction of the population. We really, really need serologic studies (to see if people have been infected and have antibodies).

Coronavirus ‘is the Big One: Harvard epidemiologist

 

[SageBrush]

Serology tests can have much better specificity than that.

(1 - Specificity) is the fraction of false positives. The rest of your post does not follow

 

[EVNow]

Yet you drive a car, which is the #1 cause of adult broken bones. Why is that? Are you fearless or a cyborg?

Because I don't think I've 1% chance of an accident ending up in hospital with broken bones. Hasn't happened in 30 years *touch wood* ...

ps :

If on average people get into bad accidents and end up in hospitals with broken bones that require months of rehabilitation *3 times a year*, how many do you think would be driving ?

 

[SageBrush]

I have to go with the experts on this

You are cherry picking the expert that supports your opinion

 

[SageBrush]

I've seen a lot of discussion about herd immunity and getting lower risk people back into the economy (here and elsewhere). I mostly understand the argument from both its merits and negatives, but one thing I haven't read a lot about is how herd immunity is affected based on the longevity of personal immunity. That is, while I know we don't have data on this yet, I've heard that with other coronaviruses, immunity can only last 3-4 months. In a population where this thing is circulating on some kind of sliding time scale, what is the range of immunity duration that would allow herd immunity to actually take hold? From a lay perspective, it seems like it would have to be significantly longer than 3-4 months.

View immunity as ~ equivalent to staying at home. Then you can rephrase your question as: what is the value of a 3 month SAH mandate ?

 

[ohmman]

View immunity as ~ equivalent to staying at home. Then you can rephrase your question as: what is the value of a 3 month SAH mandate ?

Except that SAH is contemporaneous. Immunity is rolling. I'm not sure how to equate those.

 

[EinSV]

Zachary Binney, PhD on Twitter

The FDA has approved the first antibody test for COVID-19, from Cellex. It theoretically tells you if you've had it & are, as far as we know, immune for some time. Sensitivity is 93.8%, specificity 95.6%. Sounds great, right?

If only a small % have actually had COVID-19 (our best guess now) a "positive" antibody test isn't that likely to mean you're immune. If only 4.5% of U.S. has had COVID-19, + test only means ~50% chance you really had it. With lots of uninfected, lots of false +s. (2/6)​

As mentioned in my earlier post, the German scientists reported >99% specificity for their test, and they estimated 15% infected so false positives seem to be ruled out as an explanation for the high level of infections.

 

[SageBrush]

Except that SAH is contemporaneous. Immunity is rolling. I'm not sure how to equate those.

That is why I wrote 3 months instead of 4. The middle month of a curve is the lion's share of cases.

 

[SageBrush]

As mentioned in my earlier post, the German scientists reported >99% specificity for their test, and they estimated 15% infected so false positives seem to be ruled out as an explanation for the high level of infections.

False positive RNA tests ?

Your question has always been infected but not tested. That is entirely different

 

[bkp_duke]

anti-viral development

COVID-19

FYI, those are all vaccines, not antivirals.

 

[EinSV]

You are cherry picking the expert that supports your opinion

Nope.

CDC, WHO, Harvard, Stanford, Robert Koch Institute in Germany and many, many others are urgently pursuing this (in addition to the German and Danish studies mentioned this morning). Scott Gottlieb also has been pushing for this (see below)

CDC and WHO have established protocols for labs who want to participate to try to get good antibody studies from regions around the country and around the world. Your views are out of step with the experts on this.

 

[EVNow]

Something else to consider when thinking about people laying themselves off voluntarily for 3+ months. Most Tesla's subtiers do not pay $25/hr so they are better off financially by quitting.

BTW - are these guys getting insurance when they quit ? That can make a big difference.

Also, we pay $20/hr+ for our nanny. Why are these people in manufacturing making less ?

 

[EinSV]

False positive RNA tests ?

Your question has always been infected but not tested. That is entirely different

No -- >99% specificity is for the German antibody test, per my earlier post.

"(anti-SARS-CoV2 IgG positive, method specificity>, 99%)"

 

[EVNow]

I've seen a lot of discussion about herd immunity and getting lower risk people back into the economy (here and elsewhere). I mostly understand the argument from both its merits and negatives, but one thing I haven't read a lot about is how herd immunity is affected based on the longevity of personal immunity. That is, while I know we don't have data on this yet, I've heard that with other coronaviruses, immunity can only last 3-4 months. In a population where this thing is circulating on some kind of sliding time scale, what is the range of immunity duration that would allow herd immunity to actually take hold? From a lay perspective, it seems like it would have to be significantly longer than 3-4 months.

From what I've seen from Brad and others on this virus mutation - they expect low level mutation. So, the immunity should last longer compared to Flu (that mutates very fast).

Also, the expectation is that when impactful mutations occur - it is likely to mutate towards lower CFR (that's how common cold has survived).

The other thing is - the way this virus gets into the cells using ACE-2 receptors is with the help of S proteins. So, if the anti-bodies (and vaccines) target S proteins that should be good enough. If the virus mutates around S protein, it can no longer be that deadly.

 

[Norbert]

Preliminary results of serological testing in a hard-hit area in Germany is out and the results are very interesting.

They tested every participant in the study by PCR and found 2% infected.

But antibody testing (IgG/IgA) found 15% had been infected -- 7.5X higher.

https://www.land.nrw/sites/default/...ischenergebnis_covid19_case_study_gangelt.pdf (in German)

Unfortunately, my translation is "Page Not Found".

 

[dgodfrey]

I keep seeing this comparison to the flu . . . but does anyone realize those flu deaths are with ZERO social distancing?

SARS-CoV2 is on track in 2-3 months eclipse total yearly influenza deaths, and that is WITH social distancing.

Let's all let that sink in for a few minutes, OK?

But without a semi-effective vaccine.

 

[Norbert]

That's all? Just a non stupid population? Hah! In that case, the United States is toasted.

We are certain about 50% is stupid. We just don't agree on which 50%.

 

[bkp_duke]

But without a semi-effective vaccine.

That is true, that is a confounding factor.

 

[EVNow]

In the German test, for example, they reported that specificity was greater than 99%, and they estimated 15% of the population infected. And from the press reports, 15% was considered conservative.

That town in Germany is the hotbed of infections there, IIRC. I had posted some post about this earlier.

Here is the thread on this in Reddit. Also a much better translation in the comments.

Heinsberg COVID-19 Case-Cluster-Study initial results : COVID19

They are suggesting an CFR/IFR of 0.37% - similar to my expectation (I thought CFR would be 0.5%, IFR lower).

Gangelt (12,529 inhabitants) in the Heinsberg district. The World Health Organization (WHO) recommends a protocol in which, depending on the expected prevalence, 100 to 300 households are randomly examined. This random sample was coordinated with Prof. Manfred Güllner (Forsa) to ensure its representativeness.​

Preliminary result: An existing immunity of approx. 14% (antiSARS-CoV2 IgG positive, specificity of the method >.99 %) was determined. About 2% of the persons had a current SARS-CoV-2 infection detected by PCR method. The infection rate (current infection or already been through) was about 15 % in total. The case fatality rate in relation to the total number of infected persons in the community of Gangelt is approx. 0.37 % with the preliminary data from this study. The lethality rate currently calculated in Germany by Johns-Hopkins University is 1.98 %, which is 5 times higher. The mortality in relation to the total population in Gangelt is currently 0.15 %.
​

ps : We should not be surprised if 15% of population in NYC or Lombardy has been infected.