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Interactive model showing effectiveness of airport screenings to catch Covid-19 (cmmid.github.io)
54 points by edh649 on March 1, 2020 | hide | past | favorite | 31 comments



I thought with this virus you can be be infected but not show symptoms for many days?

Hence when HHS sent untrained staff with zero protection to meet all the infected people and then they returned all over the country afterwards on commercial flights, they essentially screwed the entire USA in one easy step, practically malicious idiocrasy.


People hear this statement and think it means that anyone that is exposed and catches the virus is able to infect anyone else, just the same as if they were completely symptomatic. But it doesn't mean it is as likely. People with symptoms are more contagious, people without symptoms are less contagious. One simple reason why is that people without symptoms tend to cough and sneeze less.


IIRC there was a study done showing symptomatic and asymptomatic carriers had the same virus load. So while you simple reason is correct, there's not much else if I understand things correctly (please correct if wrong.)


I would be interested to see that study. My understanding is that the WHO, CDC, & EU all say that asymptomatic shedding theoretically possible but highly unlikely?



True! But one of the major means of transportation for that virus is by coughing, which people do rarely if they are asymptomatic. Sharing drinks or other means of liquid transmission still occur, but coughing is the big one as it takes infected throat and lung fluids, and flings them all over everything. Same reason doctors really push using tissues for sneazing if you have a cold.


You don't touch surfaces, trays, etc. at airports?

When was the last time you think they sanitized anything at TSA?


Touching a virus doesn't guarantee you being infected. It can't penetrate skin. Inhaling a droplet of saliva that somebody coughed up is much worse.


> I thought with this virus you can be be infected but not show symptoms for many days?

The tool takes this into account and lets you adjust the mean time before symptoms show (and the proportion who carry the virus without any symptoms).


According to the BAG (Swiss Bundesamt für Gesundheit), people are most infectious when they are experiencing the most symptoms (Fever etc.). People without symptoms are also not coughing/sneezing around which reduces the likelihood of spreading it which is probably significant enough to make a difference.


It's a numbers game. A tool doesn't have to catch everyone for it to help.


It keeps on crashing for me


It is a bug :)


I’m thoroughly confused. Why isn’t details of airport screening mechanics available? IIRC with SARS thermal cameras were used to screen passengers with a fever. I expect some technical details to be shared without me having to read a bunch of code (with a high probability of misunderstanding something).


This is just a tool used to explore the data. There's a link to the actual screening paper at the top of the page (https://www.eurosurveillance.org/content/10.2807/1560-7917.E...), which cites the sensitivity exit/entry scanners of infrared thermal image scanners at 86% from https://journals.plos.org/plosone/article?id=10.1371/journal...


The tl;dr: Health security theater catches about half of cases. Wouldn't the prudent step be to globally announce a two-week quarantine of all arriving passengers? In other words, not a total shutdown but slowing to prevent spread rather than foolishly squeeze out some short-term, imaginary economic gains. It may not be at all popular, but it would be the moral and ethical thing to do.


It’s easy to sit in an armchair and claim you’ve found the moral and ethical solution, but there are moral, ethical, and logistical ramifications to instituting a two-week quarantine on all overseas travelers including loss of life.

Are you also going to quarantine every pilot and flight attendant for two weeks each time they land, given their close proximity to possibly infected passengers? What is the point of a quarantine if it’s been shown we can’t reliably detect all cases (when dealing with such volumes)?


Point of any measures would be to slow the spread of COVID19 and reduce the likelihood of an overwhelming wave of infections that cripples the health system, resulting in greater loss of life than otherwise would occur and unrelated mortality due to said impact on health system.

Even some simple recommendations from leadership (CDC) would be encouraging to see, but we keep being fed a “nothing to see here, no need to panic” politicized message.

Meanwhile, events like HIMSS (~50000 attendees from 90+ countries meeting in Orlando March 9-13 to sell overpriced antiquated health tech software to one another and hear the likes of HHS Secretary Alex Azar deliver keynotes) are likely to be a catalyst for pandemic.


> Even some simple recommendations from leadership (CDC) would be encouraging to see, but we keep being fed a “nothing to see here, no need to panic” politicized message.

Which recommendations are you missing? (https://www.cdc.gov/coronavirus/2019-ncov/community/get-your...)

And the advice not to panic comes from medical experts.


The recommendation that “mass gatherings” be postponed or canceled.

WHO defines “mass gatherings” as amplifiers of transmission of COVID19.

The recommendations you linked are basic infection prevention measures, but the fact is that being within 3 feet of someone infected with COVID19 (even asymptomatic) is enough to contract the virus.


Point of any measures would be to slow the spread of COVID19 and reduce the likelihood of an overwhelming wave of infections that cripples the health system, resulting in greater loss of life than otherwise would occur and unrelated mortality due to said impact on health system.

Selective travel bans would seem to be just as effective for this, and a lot more practical.


>It’s easy to sit in an armchair and claim you’ve found the moral and ethical...

This sounds like moralizing to me.

>including loss of life

How would temporarily not issuing tourist visas kill people?


Those challenges could be overcome with special protocols. The real problem would be the decimation of the tourism industries.


Health security theater catches about half of cases.

It's not security theatre when it's that effective. It provides real benefits in terms of slowing the spread of the disease.

Wouldn't the prudent step be to globally announce a two-week quarantine of all arriving passengers?

The practicalities of that make it pretty difficult. And it means that large numbers of people who don't have the disease will be kept near those who do, meaning some of them are likely to die. (As happened on the cruise ship). I don't think the morals and ethics of this are as obvious as you are making out.


Passenger traffic between the USA and the rest of the world was about 20m in March 2019. Not all of this is into the USA, but a sizable fraction must be. Quarantining millions of people in the USA sounds extremely hard.


The prudent step would be putting all resources against a vaccine and taking some risks by skipping to late stage trials for anything that looks promising. Sort of like what happened with Ebola.

Quarantines just buy you a little extra time. If there is no vaccine, the inevitable always arrives.


> taking some risks by skipping to late stage trials for anything that looks promising. Sort of like what happened with Ebola.

I was in Africa when all that went down.

The huge difference here is that the West didn't really care about giving a not-completely-tested drug to Africans in the middle of nowhere.

I don't believe they'll accept that for their own important citizens.


Oh, I 100% agree. Too politically risky.


Agreed... I remember during Ebola feeling almost as if we simply gave up trying to stamp every little possibility and instead focused on making sure the right patients made it through the system to get the right care. At the same time it’s a little hard to excuse the lack of measurements or even the ability to determine if the virus is present.


Are you volunteering to take the vaccine?


Now here's a really great example of a site that doesn't need Google Analytics and yet manages to include (and disable?) it by default.




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