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Comment by timgilbert | Hacker News Reader

I agree completely on masks being preferable to this, but I wonder whether it may have some utility anyways, because even if it does not catch many asymptomatic people, if it is widely deployed and it catches _some_ people, those people don't go on to spread the virus, and then if you deploy those measures broadly, you have managed to halt a few potentially exponential sources of spread.

I should hasten to add that I'm not an epidemiologist, so I don't know whether this is true. But my intuition suggests that even if this is just partially effective it might still be worthwhile in the context of national efforts to control the spread, which is a numbers game.

I think this is a crucial distinction between "security theater" and "hygiene theater" -- security risks are not contagious and don't have the same potential for exponential growth that virus transmission does.

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As a doctor, I really do think this is ‘hygiene theatre’ (that is, forehead/IR temperature checks).

Last week I rocked up to operate at a hospital I irregularly work at which has recently introduced checks (as opposed to all public hospitals which have had this in place since March). In theatres we were talking about how useless it was. One of the nurses said someone tested high last week. They made the person sit in a chair for half an hour and then re tested them and granted them entry. To some degree I get it. I mean, my state is only recording 15-20 positives a day across almost 20,000 tests so the pre-test probability is small. On the other hand, what’s the point of a policy if it doesn’t change anything.

Another aspect of ‘hygiene theatre’ - when the apple stores reopened in sydney I happened to be one of the first back in (by coincidence). I visited late on the first day. I was initially impressed - security guard scanning, handing masks out. Inside the sales rep who served me had a mask continually falling down his face and kept grabbing at his face and readjusting. I eventually capitulated and told him he was wearing it upside down (metal bit across bridge of nose needs to be squeezed). Mask hygiene is important but pretty much everyone is so slack with them that, whilst they may be decreasing aerosolisation, they would be actively increasing spread of body fluids on surfaces, since so many people put a mask on and then immediately give up hand hygiene.

It’s all a bit depressing

> One of the nurses said someone tested high last week. They made the person sit in a chair for half an hour and then re tested them and granted them entry.

While 30 minutes seems excessive, this makes sense. Your surface temperature is heavily biased by your environment’s temperature. Letting one settle in a controlled environment to test is reasonable to see if it’s really a fever (temperature will stay elevated) or due to environmental factors.

An issue is that anyone could ice their forehead in advance and beat the test. Dunno if too low of a temperature triggers a fail. In theory, everyone should have to sit in a controlled environment before forehead testing, but at that point, may as well do tympanic checks.

(Among many other issues, like the massive variance that’s probably accepted because of unreliability of surface temperatures as a proxy for internal temps)

It’s winter here now. It’s not true that a ‘true fever’ will keep temperature high. On night shifts when I am called to patients that are febrile (using more sensitive tympanic or sublingual thermometers) I often ask them to check again in half an hour to kick it down the road (at which time they are generally non-febrile) provided they have a known cause and are on adequate treatment. Although the Pathogenesis of hyperthermia in this instance is usually from a slightly different cause (ie bacterial rather than viral)

I biked to a non-doctor appointment in 80+ degree heat recently. A guy thermometer-gunned my forehead before coming in. I was outside and visibly sweaty, but I still had to warn him that given the circumstances, my temperature might appear a bit high. I don't know if people are really thinking through any of this.

Did it read high? I have been checked by IR thermometers hundreds of times and have never tested above 36.9C which seems to be the gate temp around here. I too have sometimes been hot and sweaty and it didn't seem to affect the results much. I cannot even enter my own apartment building without passing an IR thermo check.

I wonder how much of a difference biking made. Generating your own breeze may balance things out.

Right now where I am, air conditioning isn’t common, but it was slightly above body temperature at the peaks of each day (I guess 100F). I wonder how that worked out with scans.

From what I have read, you are most infectious in the 24-72 hour period before experiencing any symptoms.

Given that the time from infection to symptomality is as short as 48 hours, this means it may be possible to be infected by someone before either they or the person that infected them has started to show any symptoms.

There's a subtle distinction between being most infectious and infecting the most people.

You may be very infectious when symptomatic, but you're likely bedridden and the few people around you are taking some precautions.

On the other hand you may be less infectious while presymptomatic, but live a normal life, effectively infecting more people right before you "get sick" yourself.

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