Thread by @NAChristakis

I want to go on record with obvious point: large gatherings of people facilitate spread of contagious disease. The *reason* for the gathering (whether street protests for a cause I support, or GOP convention, or a sporting event) is not material to the spread of the virus. 1/

At a *minumum,* such gatherings should involve harm reduction techniques (such as masks, no tear gas, no shouting, etc.). Also, transmission opportunities rise supra-linearly with group size. So gathering of 250,000 people >>worse than 50,000 >>>>worse than 30 people. 2/

1918 flu pandemic had famous example of mass gathering (for a parade supporting WW1) in Philadelphia. The outcome was much more death, compared to other cities. 3/

And remember, the whole rationale for the coercive power of the state (which I generally deplore!) during a contagious outbreak is that individual actions impose a risk on others, not just on themselves. 4/

For instance, this behavior in Florida in April was something (rightly) seen as irresponsible from a public health point of view (and of course I myself think protests against brutality are more important than partying — but the virus doesn’t care). nytimes.com/2020/04/11/us/… 5/

Some more background, links, and extensions to the ideas in this thread hereby attached: 6/

COVID (unadjusted) killed 1/1000 of all New Yorkers (NYC) in two months, but it killed 3/1000 of all black New Yorkers. apmresearchlab.org/covid/deaths-b… That’s just first wave! It’s known COVID is an immediate threat affecting minority and vulnerable populations (eg elderly, sick). 7/

So let’s be clear: it’s not just about protestors (or anyone joining any kind of large gathering) willingly assuming risk to their *own* lives from a contagious disease. It’s that, during an outbreak, their actions impose risk on *others* incl most vulnerable. 8/

The Philadelphia Liberty Loans Parade noted above took place on Sept 28, 1918 (to sell bonds for WW1) and >200,000 people attended. This led to one of the largest outbreaks of flu in USA. It has been called "the deadliest parade in American history." en.wikipedia.org/wiki/Philadelp… 9/

By October 3, 1918, the outbreak of the Spanish flu in Philadelphia had gotten so bad that the city had to be essentially shut down. 10/

I am NOT saying this will happen again now. Effects of the current protests during COVID are unlikely to be as rapid or as large, for a number of reasons. But more cases surely result from mass gatherings during contagious outbreaks, no matter the reason for the gathering. 11/

So a tough utilitarian calculus cannot be ignored: how many extra deaths are worth it? 12/

Protestors themselves may be at relatively lower risk of dying COVID per se, being young on average (though not always, as this appalling case shows nytimes.com/2020/06/05/us/…). But, even outdoors and masked, they will bring virus home to others, and contribute to spread. 13/

More deaths than otherwise will result. Hard to say how large a bump, and how much it will be due just to these (understandable!) protests, but I think we will see a new wavelet in ~4 weeks (ie, after ~2 transmission links, given youthful age of protesters themselves). 14/

At a minimum, protestors themselves should clearly implement harm-reduction techniques. HK protesters tried to do this:

See also nytimes.com/2020/06/04/wor… and aljazeera.com/news/2020/06/t… | @gregggonsalves 15/

Medical students at @Yale tried to protest in a sensible way during a contagious outbreak recently too: newhavenindependent.org/index.php/arch… | @mearest 16/

Police should also take harm-reduction approaches, as noted earlier. The should limit tear gas, limit jail crowding, limit forcing crowds to tight spaces, and use non-escalatory techniques. Mayors should so order, as some have been (e.g., seattletimes.com/seattle-news/w…) 17/

Here is the article that got this conversation started: Suddenly, Public Health Officials Say Social Justice Matters More Than Social Distance. politico.com/news/magazine/… by @ddiamond 18/

As I said, the inconsistency here is unsound from an infectious disease epidemiology point of view, and very damaging to field of public health, in my opinion. It’s important to maintain credibility as scientists and as a field. 19/

As for my personal support of protests or my opposition to police brutality & to racialized violence, this is obvious, and my public opposition goes back decades. My research and teaching about health inequalities is longstanding. | Very proud of former students eg @Jaxhsieh 20/

I publicly supported nixing Boston Marathon & St. Patrick’s day parade, along with many epidemiologists, eg, @mlipsitch. I thought prohibition of funerals was unnecessarily stringent, since they're small events & harm-reduction could be implemented (latimes.com/california/sto… ). 21/

For similar reasons, that is, the the *size* of the gathering matters a lot to this topic (supra-linearly, actually!), I opposed prohibitions on visiting loved ones dying in the hospital. 22/

I also opposed the absurd actions during protests from the Right a few weeks ago to rapidly re-open the economy or to oppose mask ordinances. These were irresponsible. This case got a lot of attention, for instance: msn.com/en-us/news/us/… 23/

I do not think armed protest is reasonable.

I wholly support the idea that the right of the people to peaceably assemble and petition for redress of their grievances shall not be infringed.

This is why this case was so deeply wrong: npr.org/2020/06/01/867… 24/

I strongly oppose police brutality. We need to recruit, train, & equip police wholly differently, and I've been saying this for a long time. The police have a demanding & dangerous job. Let’s get right people for it, let’s keep them accountable, and let’s pay them well, too. 25/

Here is another shot from the recent protest by @YaleMed students, keeping their distance. Good. via @ThkBleu 26/

Correction! That previous tweet (#26) was at @UCLA not @Yale. 27/

For a thread estimating the transmission opportunities as group size rises, and expanding on the point about "supra-linear" growth, see: 28/

And here is a well argued piece by @AbigailShrier in @WSJ pointing out hypocrisy and loss of credibility that comes from saying some mass gatherings are valorous but not others (and, yes, I know the difference between indoor and outdoor risks, etc.). wsj.com/articles/polit… 29/

I don't know how recent is this video of Las Vegas, via @ArashMarkazi, but this dense social mixing (unmasked) is also bad from public health standpoint. I think Americans may have, for now, just decided to accept more deaths. I hope we don't regret it 30/

Here is an estimate from @trvrb: ~6000 infections per day in protestors, ~ 6000 infections per day in community, with the consequence of 30-60 deaths per day of protests (subject to MANY assumptions, including overall size of protests - see thread). 31/

Mass gatherings facilitate transmission in this study which investigates the seroprevalence in Gangelt, Germany, among those attending carnival celebrations, finding a 2.5X increase in rate of infection (they were not masked, however). medrxiv.org/content/10.110… 32/

An updated guess by @trvrb, who shares my concerns (both in terms of epidemiology and police brutality) is that each day of protests with 600k people will result in 200-1100 eventual extra deaths. Note he uses 600k & R0=0.95, and those are low. 32/ https://t.co/wgAIR79SvU

Hence, roughly speaking, for every 1,000 people who go to a mass gathering during these times of a contagious disease outbreak, per day, we may have one extra death (within a couple months). Thats a big force of mortality. That’s a cost of protest we simply must reckon with. 33/

And here is Philadelphia. I hope I’m wrong about all this, and that we squeak by. 34/

Aerial shots of crowds around the country. nytimes.com/interactive/20… 35/

In Tennessee, with one of fastest-growing COVID outbreaks in USA already (!), restrictions are lifted to allow fairs and parades. Gov. Bill Lee said "These new guidelines [allow us to] enjoy the events that connect us to our neighbors and communities." npr.org/sections/healt… 36/

More video, of protest in DC, with protestors marching while wearing masks and keeping distance. Good. At least if large groups are to assemble, they (and the police!) should imply harm reduction techniques. 37/

The politicization of the epidemiology will be awful when COVID19 deaths come in. The R will blame protestors. The L will blame police & officials for their tactics. The R will say "look, we can ignore all other restrictions." The L will say "racial injustice is special." 38/

Powerful, amazing, enormous protest for causes (ending police brutality and the racialized application of justice) I have long and wholly supported. Quite worrisome from the point of view of an active epidemic, however. 39/ https://t.co/y6KH7OcOxl

Terrific @guardian column on this dangerous inconsistency by @thomaschattwill. theguardian.com/commentisfree/… "Public health experts have hemorrhaged credibility and authority. This is not merely a short-term problem; it will constitute a crisis of trust going forward." 40/

I somehow had missed this pointed and sage June 4 column by @conor64 in @TheAtlantic pointing out the difference between scientists actually quantifying and stating the risk of protest gatherings, versus arguing that this risk should be tolerated. theatlantic.com/ideas/archive/… 41/

I would like to go on record that holding such large political rallies -- involving lots of people in close proximity and possibly yelling -- is ill advised during a time of a serious respiratory pandemic. politico.com/news/2020/06/0… 42/

Now @walterolson points out further wrinkles that emerge, legally speaking, from inconsistent policy (from epidemiologists, public health officials, & government authorities) with respect to gatherings: (I realize one cannot easily stop huge protests!) 43/

And @NateSilver538 analyzes poll results indicating how mixed messaging may have played out. As a polity, we may have wholly sacrificed any ability to proactively use physical distancing as a tool to fight a deadly pandemic. 44/ https://t.co/2JWducTb00

Essay by @JuliaLMarcus & @gregggonsalves re "hypocrisy" re COVID19 & protests is a bit loose in couple of spots, IMHO, but I think it's thoughtful. I agree with most of it. But a key issue is that protesters impose risks on others, not just themselves. theatlantic.com/ideas/archive/… 45/

This kind of concurrent hypocrisy is very bad for confidence in both public health policy and politicians. For instance, children playing can easily be construed as a public heath issue. nationalreview.com/news/nyc-autho… 46/

And now this (if true?): "NYC contact tracers have been told not to ask anyone who’s tested positive for COVID-19 whether they recently attended a demonstration." But will they ask if they’ve been to church or a ball game? Sheesh. thecity.nyc/platform/amp/c… via @thomaschattwill 47/

This rally slated for Oklahoma is a very bad idea with respect to the spread is the coronavirus. It’s irresponsible and it’s quite likely some additional people will die as a direct result. At a minimum it should be held outdoors. nytimes.com/2020/06/16/us/… 48/

Useful data re SARS-2 positivity for protestors from two groups in MN: 1) of 3,150 tests by Mayo Clinic, 1.8% were positive; 2) of 8,500 tests by Health Partners, 1% positive. So far, no bump, but we must wait another serial interval or so. :-) medpagetoday.com/infectiousdise… @trvrb 49/

This is awful from many points of view, but especially from the point of view of a deadly contagious disease. 50/ https://t.co/IZAHsT8BNy

New data! Fine @nberpubs paper w @SafeGraph data shows that, at 2.5 wk follow-up, BLM protests NOT associated w COVID19 spike. Not too surprising; must wait ~2-3 more wks. Paper also wisely notes compensatory simultaneous rise in stay-at-home behavior nber.org/papers/w27408.… 51/

I’m sorry this thread is so long & complex, but this complicated story isn’t over. A federal judge holds inconsistency of politicians in public health against them, as he logically would have to. Thus we lose a powerful public health tool. Foreseeable. amp.democratandchronicle.com/amp/3263469001… 52/

Another update w @SafeGraph data from WI & DC suggests a “Lack of Impact of Protests on Aggregate Activity.” Protests in some areas may not have been large enough to impact overall activity, or perhaps had offsetting decreases in non-protestor activity crowe.wisc.edu/wp-content/upl… 53/

PSA The *reason* for the gathering does not matter to the virus. This is a bad idea. 54/ https://t.co/IfLnS7sS4U

Nice coverage of conflict in values, and the sometimes personal struggle w hypocrisy, in epidemiologists in the wake of protests, w some honest self-reflections, via @powellnyt

Are Protests Unsafe? What Experts Say May Depend on Who’s Protesting What nytimes.com/2020/07/06/us/… 55/

Wholly to be expected. Irresponsible and foolish. nytimes.com/2020/07/08/us/… 56/

It is irresponsible to hold this wedding, and government authorities rightly are banning it. However, why did the same authorities not do the same for protests involving many more people? This inconsistency is bad for public health communications. cnn.com/2020/10/19/us/… 57/