There remains an enormous amount we do not know about SARS-CoV-2. On the one hand we may be a very long way away from achieving “herd immunity” to SARS-CoV-2, the point at which enough people have resistance to the cease that its spread ceases or slows, as this piece at The Telegraph avers:
Dr Jefferson believes many viruses lie dormant throughout the globe and emerge when conditions are favourable, which also means they can vanish as quickly as they arrive.
“Where did Sars 1 go? It’s just disappeared,” he said. “So we have to think about these things. We need to start researching the ecology of the virus, understanding how it originates and mutates.
“I think the virus was already here – here meaning everywhere. We may be seeing a dormant virus that has been activated by environmental conditions.
“There was a case in the Falkland Islands in early February. Now where did that come from? There was a cruise ship that went from South Georgia to Buenos Aires, and the passengers were screened and then on day eight, when they started sailing towards the Weddell Sea, they got the first case. Was it in prepared food that was defrosted and activated?
“Strange things like this happened with Spanish Flu. In 1918, around 30 per cent of the population of Western Samoa died of Spanish Flu, and they hadn’t had any communication with the outside world.
“The explanation for this could only be that these agents don’t come or go anywhere. They are always here and something ignites them, maybe human density or environmental conditions, and this is what we should be looking for.”
I think that the genetic studies contradict that view but I present it in the interest of completeness. On the other hand herd immunity may be just around the corner as Allysia Finley declaims in the Wall Street Journal:
A small study last month from France found that six of eight close family contacts of sick patients didn’t develop antibodies but did develop Covid-19-specific T-cells. A new study from Sweden finds that moderately ill patients developed both Covid-19-specific antibodies and T-cells. But twice as many healthy individuals who donated blood during the pandemic and asymptomatic family members of sick patients generated Covid-19 specific T-cells than did antibodies.
“SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19,†the study concludes. “The observation that most individuals with asymptomatic or mild COVID-19 generated highly functional durable memory T cell responses,†not uncommonly in the absence of antibodies, “further suggested that natural exposure or infection could prevent recurrent episodes of severe COVID-19.â€
In short, antibody tests may significantly underestimate the number of people who have already been infected with Covid-19, especially if they had a milder strain. If so, it’s possible that some early hot spots, like New York City and northern Italy, already have a degree of herd immunity. The same may be true of other places soon.
There is some controversy about what percentage of the population must not be susceptible to the virus in order to achieve “herd immunity”—anything from 33% to 95% has been suggested. It would seem to me that graph theory would suggest that the actual percentage may depend very highly on circumstances.
“Schrödinger’s cat” was a thought experiment devised by the physicist Erwin Schrödinger. The scenario presents a hypothetical cat that may be simultaneously both alive and dead. Similarly, SARS-CoV-2 seems to be “Schrödinger’s virus”—simultaneously everywhere and nowhere.
My own view is that we should be making a drastically different set of assumptions than policymakers seem to be making, based on experience. “Spanish flu”, the flu that infected nearly a third of Americans in 1918 and killed millions worldwide, never vanished. It is still with us. It is now called A(H1N1) and broke out a decade ago as “swine flu” and people are still contracting it. It is a serious flu, more deadly than the seasonal flu, but we aren’t destroying our economy and society over it.
Let’s not assume that a vaccine will ever be produced for SARS-CoV-2 and that we never actually achieve “herd immunity”, whether because not enough people are susceptible to it or it evolves just fast enough to evade our immune systems. It seems to me that the appropriate measures for me, personally, to take given that assumption is to take the measures that seem prudent to avoid contracting the disease but otherwise just accept that life cannot be risk-free.
Under those circumstances what would be the most prudent public policies?
1) Wear a mask when out and around other people. Avoid groups of people that are not wearing masks.
2) Avoid large groups, especially crowded indoors groups.
3) Outside is safer than inside. If you need to exercise or vacation out doors is better. No data but I am betting that if you have a choice between a crowd outside and no mask vs a crowd inside plus a mask, you are better off outside. Public policy should steer people in that direction. We should also have research to confirm this.
4) Don’t go to work if you feel sick and ask that your workplace emphasize that in its policies. (Fully realize most people don’t have the ability to influence those kind of decisions at work, but it could be encouraged/required by policy. Hard to enforce so I think I would favor encouragement.)
5) Get better at tracking and tracing. This doesn’t have to be 100% effective to help. If we are going accept some risk then we have to accept some failures.
6) We need a fairly large and coordinated team of workers and equipment that can move to places that risk being overwhelmed. In the ideal, we also bring extra hospital workers. Being in a small group of physicians who has actually practiced in tents I am not a real fan of the instant hospitals people propose. They work in the military for a couple of reasons. Mostly because your treatment population is much younger and healthier than the general population. You have an extensive air-evac system so you can move people out quickly (most of the time). You also have people who are used to working together who train to work in those hospitals.
You also need to start now and have hospitals set up systems for transferring patients to those extra hospitals. This will be a nightmare since most places have EMRs and they are all different. Every EPIC design is slightly different. (They claim that with every build 40% of the build is standard and 60% is customized. No idea if that is actually true.) Most hospitals compete with each other unless they are in the same network and it is difficult to communicate out of your own network. (The reality is that no one is going to do this ahead of time. It will be done at the last minute and the “instant” hospitals will be pretty useless at first until all of this is figured out.)
Steve
At this point; focus on an effective therapeutic / vaccine.
In some sense; the biggest scientific question is why so many are asymptomatic / mildly ill but 5-20% end up severely ill. We know the risk factors (age, co-morbidities) but there is no biological explanation why it triggers the severe disease in a few but not all.
If they could reduce the risk of getting the severe disease / mortality by 90%; we probably treat it as if it were the flu.
Strange things like this happened with Spanish Flu. In 1918, around 30 per cent of the population of Western Samoa died of Spanish Flu, and they hadn’t had any communication with the outside world:
Postulate:
Bird droppings on fruit.
Much we don’t know.
All it might require is one guy debarking from one small boat. It doesn’t take cruise ships full of passengers. How do you preclude such a thing?
But he’s wrong about Western Samoa. On 7 November 1918 the SS Talune landed there and its crew debarked in breach of the quarantine. It was after that the flu began to spread there.
Baseball is going to test every other day (for almost 4,000 people), report test results within 24 – 48 hours, and provide for isolation of those who test positive. The results at intake appear to be that under two percent of players were infected. They are pooling the samples to save costs on materials, the tests might be as low as $3 per sample.
Paul Romer is beating the drum on a similar approach to opening schools, recognizing that social-distancing is generally not possible, but frequent testing would achieve the same result (though he believes test frequency will need to depend on prevalence in the community), but K-12 schools would probably need federal funding.
https://paulromer.net/congressional_funding_tests/
Such testing would be more useful in nursing homes, but probably useful where any employer is requiring temperature scans to enter the premise.
My employer is requiring temperature scans to enter the premises, encouraging handwashing, mandating the wearing of masks, and dividing the employees into two groups with only one group on premises in a given week.
Nate Silver has tried to create a pneumatic to avoid the three Cs (closed spaces, crowded places, and close-contact settings). Not sure it works for me, I think he means ENclosed spaces, but most of this seems redundant.
I think policy should push towards maintaining work-at-home options where possible, particularly in the more dense downtown work environments. I think the problem is that a lot of people aren’t as productive at home, and there are some benefits to shared physical proximity in many jobs. But if we can nudge greater job flexibility, even if its only certain days of the week, or times of day, I think we would benefit from reduced crowding and contact.
Also, been wondering if the Americans with Disabilities Act might require at-home option where practical if the person has a condition that puts them at great risk from infection.
Edit: I wrote this before reading Dave’s response; dividing workers into shifts is one of the things I’m thinking about.
Like Steve’s list, except for 5, but he caveats it. Also think curious hits a nail on the head. Just why are a very few of the not obvious at risk parties so dramatically affected? That would be huge not just from an academic view, but on how to focus efforts.
As always. Common sense is a huge fraction of the solution. Don’t over engineer it.
The baseball players will soon look like coke heads having a swab shoved down their nasal passage every other day, but I hear they are starting to come out with less invasive tests.
Response to the T cell paper.
https://twitter.com/BenjaminMeyer85/status/1280257221587320835
Steve