COVID19 update, June 30, 2020: droplet and aerosol transmission; herd immunity requires as little as 20%?

Been a very busy day at work, but let me just share with you two things:

(a) a long essay that Jeff Duntemann drew my attention to:

Aerosols, Droplets, and Airborne Spread: Everything you could possibly want to know by Justin Morgenstern MD, an emergency physician located in the greater Toronto area.

The essay is long but very much worth your while.

(b) Coronavirus: could it be burning out after 20% of a population is infected? We pointed earlier to a preprint that showed that, if susceptibility to the infection isn’t assumed to be all or nothing, that this leads to a second-order mathematical model that predicts much lower herd immunity thresholds than the common first-order model. See also (h/t: masgramondou): 

But it is unlikely that lockdowns alone can explain the fact that infections have fallen in many regions after 20% of a population has been infected – something that, after all, happened in Stockholm and on cruise ships. 

That said, the fact that more than 20% of people have been infected in other places means that the T-cell hypothesis is unlikely to be the sole explanation either. Indeed, if a 20% threshold does exist, it applies to only some communities, depending on interactions between many genetic, immunological, behavioural and environmental factors, as well as the prevalence of pre-existing diseases. 

Understanding these complex interactions is going to be necessary if one is to meaningfully estimate when SARS-CoV-2 will burn itself out. Ascribing any apparent public health successes or failures to a single factor is appealing – but it is unlikely to provide sufficient insight into how COVID-19, or whatever comes next, can be defeated.

COVID19 update, April 13, 2020: Italy and Israel grappling with exit strategies

(1) Italy, which has seen mortality well past the peak and on a downward trend (on a moving average) since the beginning of the month, and where new cases are lowest since March 13, is starting to grapple with “the day after”. As reported earlier, both Austria and Denmark are starting the road back to normal on April 15, with Norway to follow suit on April 20. Spain has started some normalization measures today.

(2) Israel too seeks to emerge from its “induced economic coma”. [Not all sectors have been idled: in fact, transportation infrastructure works have been carried out ahead of schedule as they were minimally disruptive now.] COVID19 cases have crossed the five-digit threshold here and are still increasing, but this is nearly compensated by an upswing in the number of recoveries, leading to an apparent stabilization in the number of active cases. Sure, we’re not out of the woods yet, as deaths have now grown into triple digits, but according to deputy director general of the health ministry, Itamar Grotto:

“I think we can say that we’ve pretty much succeeded in the stage of stopping the spread” of the coronavirus. Speaking to Ynet, he said that although there could be unexpected results from the outbreak in Bnei Brak and some other [c]hare[i]di communities, which would only be seen in the next few days, “It can be said that we’re in a relatively stable situation, and we’re in the stopping phase. Now, we need to see how we get out of this.” 

A group of captains of industry and business published an open letter, calling to start reopening things after Passover, “or face economic collapse”. Well, according to Haaretz (h/t Mrs. Arbel; I will deviate from my usual policy of not sending links there) these are the recommendations of the National Security Council, in four phases:

Phase 1: could begin as early as Thursday. In a nutshell: 

  • hi-tech and finance sectors reopen, as distance compliance etc. easier to assure there.
  • Government offices, currently down to essential staff, are ramped up to 50% staffing again
  • Preschools and special education are reopened. (Preschoolers are least in danger from the virus.)
  • It is being considered to permit preparation of small groups of HS seniors for their Bagrut (matriculation) exams
  • Public transportation, currently running on a severely curtailed schedule, to be partially restored again

Phase 2: two weeks later

  • Reopen retail stores other than large shopping centers
  • Elementary schools reopen

Phase 3: two more weeks later

  • Reopen remaining stores
  • Reopening cafes, restaurants, and hotels with social distancing and hygiene restrictions 
  • Junior high and high schools reopen. Strict hygiene and social distancing required
  • Universities and other postsecondary education will continue online teaching until the end of the school year, as they have already adapted to this
  • large, crowded events will still be prohibited

Phase 4: only when pandemic is under full control

  • Leisure and entertainment industries back in operation
  • Flights resume
  • Anyone over 60 and at-risk populations still under lockdown

One main worry expressed is whether, if a flare-up occurs, the public will abide temporary back-tracking.

Some might wonder if gregarious and notoriously “in your space, in your face” Israelis will adjust to a new normal of keeping at two arms’ length and no touching, hugging, backslapping, kissing,…

UPDATE: welcome, Instapundit readers!

COVID19 update, Eve of Passover edition: eyeing the long road to normality

Ezekiel Emanuel (brother of Rahm Emanuel) — whose ‘peculiar’ views on medical ethics would require a separate blog to fisk them — now calls for a 12-to-18-month lockdown. Bill Gates, not a doctor but somebody I’d expect to at least understand supply chains, argues for a 6-month lockdown until a fast-tracked vaccine would be available.

Only somebody who is completely divorced from any economic and social reality outside medicine would present such extended lockdowns as anything other than “in an ideal world, we’d wish we’d be able to do this. In the real world, this would kill the patient while curing the disease”. Sarah Hoyt has been expressing her fear of the latter repeatedly and stridently on her blog.

Even now, the economic fallout from lockdowns is immense, although perhaps less felt in some countries than in others. France, for instance, routinely goes on a nearly month-long collective vacation in August, and Israel nearly shuts down twice a year around Passover and around the High Holidays. But these are scheduled, cyclical events that these economies have been working around for decades.

There are already the first signs of food supply chain disturbances in the US. (With “just in time delivery” chains, that happens faster perhaps.) In this small country here (Israel), agriculture is more or less business as usual, though the shutdown of cafés and restaurants has meant that some farmers primarily selling to that sector now are having to dump vegetables and dairy products at a loss. Some have gotten creative and have branched out into home delivery.

Instapundit says, “we can keep this up for another two weeks at most, and then we have to start reopening things”. Considering hopeful signs that the epidemic has reached plateau phase in its US epicenters, this may actually be realistic. Austria, where active cases are past the hump, has committed to a phased reopening of the economy. Belgium, where the infection is peaking, is looking at doing the same, as is Denmark. Israel’s initial contingency planning was for reopening in stages after the week-long Passover holiday; it’s not clear whether that is still in the cards, but planning is going on, and the planners openly discuss the trade-offs involved. As one put it: “we might have world-class epidemiological statistics” (Israel’s IFR is well below 1%) “but wreak irreparable damage to our economy that may cause more mortality in the elderly than the virus”.

Some advocates of sustained strident measures quote Tomas Pueyo’s “The Hammer And The Dance” essay without context. Actually, Pueyo argues precisely for an alternative to extended lockdowns. What he called for were:

1) In the “Hammer” phase, carry out as stringent a lockdown as possible, as early as possible, such that the period required for breaking the back of the epidemic is as short as possible (ideally, get effective reproductive number down into the 0.35 range).

2) In the “Dance” phase, reopen things with social distancing & hygiene restrictions in order to keep the effective reproductive number R from exceeding 1.0. Ideally, with abundant statistical data (which he admits may not be available) one would be able to establish a kind of “menu” of R-reduction options, and be able to assemble a combo of the options that give the most benefit for the least economic cost.

What does the latter mean in practice? Just by way of illustration: frequent hand-washing and wearing masks may be nuisances, but do not significantly interfere with economic activity. (Again, the primary benefit of wearing masks is to your fellow person, not to yourself. It will stop you from projecting aerosols of the virus unto others if you are in the asymptomatic phase.) Respecting the personal space of others may seem annoying to Spaniards or Italians (or Israelis, for that matter), but is a way of life to many people elsewhere. I was astonished when last year I visited various stores in Norway where people routinely stayed a meter apart from each other in line, without pushing or becoming impatient. Likewise, many Americans who haven’t been conditioned to dense urban areas like NYC respect personal distance better than most others.

And some aspects of the world economy may change forever, and not necessarily for the worse. Some jobs that can be done just fine by video link or other electronic communications may never return to one-on-one. And conversely, many countries and large corporations will be reconsidering the wisdom of being overly dependent on a single supplier for anything crucial. The diversification process had already started, but will go much further. The PRC is sure to feel the economic repercussions of this — at a level that may jeopardize the survival of its totalitarian regime.

DE STANDAARD (in Dutch) looks at six possible strategies for “back to normal” in Belgium, which I will briefly summarize

1. Test and trace. Main downside, aside from required testing capacity, is privacy invasion through phone app. (South Koreans don’t GAF)

2. Gradually opening schools and businesses, while continuing distance learning and telecommuting in such sectors where this is feasible. Mass events (concerts etc.) remain off the menu

3. Immunity testing and immunity passes — those who have them can go back to work. Main downsides: antibody tests not yet reliable enough; not proven that one cannot get reinfected after getting cured; probably fewer people have immunity than many advocates think.

4. Masks for everyone. Main downsides: not enough masks for everybody; false sense of security; people not used to using them start futzing with them and touching their faces, which (if hands contaminated) makes it worse

5. Variolation [they call it instead “Hotel Corona”] of younger people to build up “herd immunity”. Main downside: not clear if this is really as safe for young people as generally thought. Erika Vlieghe, head of the Infectious Diseases Dept. at U. Of Antwerp, mentions genetic predisposition to overreacting immune system (“cytokine storm”) in some people.

6. Miscellaneous “out of the box” approaches, such as staggered lockdowns (alternating odd and even ID numbers, alternating male and female, alternating odd and even DOBs) to ensure fewer people in public spaces at any one time; release one region/province at a time while keeping the remainder on lockdown, keeping excess hospital capacity available in the other regions in case of a flare-up in the opened region;…

Meanwhile, the observation that China is trying to rewrite the history of the virus is not just the province of “les déplorables” in the US: the center-right German daily Die Welt — as “establishment” as you can get — has an article arguing exactly that (Alas, they have plenty of Полезные идиоты in the mediatainment complex.)

To my fellow Jews, have a wonderful Passover, with or without electronic means of distance participation in the Seder.

And to all, my best wishes for health, well-being, safety, and may we soon see the light at the end of the tunnel.

COVID19: March 21, 2020 update

(1) Israel saw its first death from the epidemic, an 88-year old Shoah survivor from Jerusalem named Aryeh Even. May his memory be for a blessing.

The total number of patients reached 883. Despite “soft lockdown”, people still went out to the beach and to national parks.

(2) Neuroscientist and sci-fi author Robert E. Hampson: reports on an Icelandic biotech company has been organizing a free testing program running in parallel with the official one, and where everybody can ask to be tested. Presumably the purpose is to gather better data about what the small island nation is really dealing with. (At about 335,000, they can in principle test their entire population.)

The biggest takeaway of the results: about one-half of those who tested positive never got ill at all — a number congruent with what is seen on the Diamond Princess.

(2b) From the same post, a preprint on MedRXiv (DOI 10.1101/2020.03.05.20031773 ) of a detailed epidemiological analysis of the Diamond Princess data and of the China data. The central result: they estimate an IFR (infection fatality rate, i.e., dead per number of people infected) of 0.5% (one-half percent), with a 95% confidence interval running from 0.2 to 1.2%, and a CFR (case fatality rate, i.e., dead per number of people who actually get sick) of 1.1%, with a 95% confidence interval running from 0.3 to 2.4%. I certainly hope it’s closer to the bottom than to the top of these CIs.

Israeli epidemiologist Dan Yamin, interviewed here in Haaretz (archive link) argues for low figures as well, and (very much to the distaste of Haaretz’s small, leftist readership) gives Trump’s response positive marks and the WHO’s negative marks. He also stresses what I’ve been suspecting: that anomalously high apparent CFRs in some countries (notably Italy) reflect a selection bias in testing, with scarce testing resources being applied primarily to cases with an already probable COVID19 diagnosis. (Link via Jordan Schachtel.)

We need more and faster testing, and we need it yesterday.

Happy first day of spring, stay healthy, stay safe, stay calm.

Addendum: somebody forwarded a graph highlighting the flatter case incidence graphs for countries like Taiwan, South Korea, Japan, as well as for Hong Kong. Correlation is not causation, of course, and particularly the Japanese by default practice a considerable degree of social distancing on the micro level, but in all of these places, wearing face masks when one has even the slightest hint of a respiratory infection is common social custom. Wearing a mask prophylactically when one is not feeling ill: somebody who lived in Japan for a long time told me people won’t routinely do it except in flu season, but it is definitely socially acceptable.

Addendum 2: The Johns Hopkins COVID19STATS dataset is online here.

Addendum 3: HonestReporting produced this brief memorial video for Aryeh Even z”l.

Containment measures may create an offsetting factor for COVID-19 mortality

Something occurred to me as I saw a sign in our elevator telling us to refrain from leaning on the sides, and to wash our hands upon entering the house:

The excess mortality from the current COVID-19 epidemic may be offset to a smaller or larger extent by the mitigating effect “social distancing” behavior will have on seasonal flu.

Keep in mind that every winter, according to CDC data, complications from seasonal flu account for as many as 61,000 excess deaths (winter of 2018-9) in the USA. Many of the people dying are the same as are most at risk from COVID-2019: the elderly, the immunocompromised, people with chronic illnesses. A very nontrivial percentage of these deaths are preventable not just through vaccination, but also through sensible social distancing and hygiene measures. The latter applies even more outside the USA, for example in much of Europe or in the Middle East where the concept of “personal space” is nearly foreign.

Yes, you say, but few people die directly from seasonal flus, and most deaths are actually from opportunistic superinfections (usually pneumonia). True, but: (1) the end result for patients is, sadly, the same; (2) more and more bacterial pneumonia is caused by multiply antibiotic-resistant strains against which the usual pharmaceutical arsenal is increasingly powerless. (I’ve lost a couple too many colleagues and friends to resistant infections that would have responded quickly to antibiotics 30 years ago.); (3) many of these people would never have gotten the same pneumonia if their immune systems weren’t already dealing with the flu.

A friend who is a geriatric nurse told me that many of the social distancing and hygiene measures now recommended for COVID-2019 are just more stringent reiterations of what she’s been telling people to do for years.

Even if they were to make only a 10-20% dent in excess mortality from seasonal flu epidemics, that would be a reduction of 6,000-12,000 in the USA alone that would offset the increased excess mortality from this novel respiratory infection. It may sound like a meager silver lining on a dark and uncertain cloud, but it is definitely some positive food for thought.

Meanwhile, stay well, stay safe, and let us hope we will all weather this storm as well as can be. It is good to remember the whole quote from FDR’s inaugural address:

So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself — nameless, unreasoning, unjustified terror which paralyzes needed efforts to convert retreat into advance.

UPDATE: Some “anecdata”: Friends who live in the North of Japan counts a number of local healthcare professionals among their friends. Normally, a hefty percentage of case load at the local hospital consists of elderly with complications from flu or viral pneumonia. Reportedly, things are much slower in that regard since COVID-19 got people minding their social distance again…