Is it possible to travel responsibly (during a pandemic)?

[Jcp2]

Dogs are really more intelligent than what we give them credit for, just not in the ways we expect.

Eliminating Police Bias When Handling Drug-Sniffing Dogs

 

[drrich2]

NBC Nightly News Jan. 30 reported there is now a confirmed case of the South African variant in Maryland. Which is not adjacent to South Carolina. I'm gonna date myself with the creepy little girl warning from the movie Poltergeist when I was a kid - 'They're heeeere....'

 

[scubadada]

NBC Nightly News Jan. 30 reported there is now a confirmed case of the South African variant in Maryland. Which is not adjacent to South Carolina. I'm gonna date myself with the creepy little girl warning from the movie Poltergeist when I was a kid - 'They're heeeere....'

...and SE FL leads the US in cases with the UK strain

 

[ontdiver]

Some days I think Bizarro World wouldn't be so bad after all.

 

[uncfnp]

If they make this practical I could see it preboarding in certain circumstances.

https://medicalxpress.com/news/2021-01-smartphone-based-covid-results-minutes.html

 

[apenland01]

Something like this could be really helpful as well...

QuikLAB - Rapid COVID-19 Testing with results in minutes

 

[Jcp2]

Can I play again? Let’s say the test is 90% sensitive and the disease is 10% in prevalence. That means there is a 10% chance of marking a person who is positive as negative, or 10% of 10%, so negative predictive value is 99%. That’s pretty good. Let’s let 25 people on board including crew. 0.99 to the 25th power is 0.78, so there’s a 78% chance your tested bubble is a real bubble, so a 22% chance that at least one person on board is infected. I’ve been vaccinated with presumed 95% effectiveness against symptomatic infection, so that works out to about an end 1% chance I would get sick, and essentially 0% chance of being sick enough to require hospitalization. I would take that chance, but only because I got the vaccine, not because they are doing testing.

 

[drrich2]

Can I play again? Let’s say the test is 90% sensitive and the disease is 10% in prevalence.

You made me think of a lecture decades ago where you teacher taught us about sensitivity, specificity and the predictive value of a positive (or negative) result. He used HIV as the disease, but COVID-19 would serve as well. He gave us some basic definitions (going off recall here; sorry if I bungle something):

1.) Sensitivity - the odds someone with the disease tests positive.
2.) Specificity - the odds someone who does not have the disease tests negative.
-----That's very important. Think about it...a test that comes back positive for everyone, every time, is 100% sensitive...and 100% useless.
3.) Population prevalence is a key factor. He just made up the hypothetical population incidence rate of 1%, and assigned his hypothetical test sensitivity and specificity to both be 99%. Sounds great, right?

He then calculated the predictive value of a positive result, the odds that someone testing positive actually has the disease. And it was pretty crappy! Turns out in that scenario you're risking a false positive on 99 healthy people for every single HIV+ person you test. Even a test with high specificity in a population with low disease rate can give a lot of false positives.

This is a big deal; an HIV+ result can be traumatic. That's why, we were taught way back, the basic HIV screening test (which needs to be cost effective and efficient to run) is followed up with a confirmatory test ( a Western Blot) - expensive and time-consuming, but more dependable.

Similarly, the modern screening tests for syphillis (VDRL and RPR), if positive, get followed up with a confirmatory test.

Where I'm going with this long-winded rant: medical screening tests cheap and quick enough to be cost-effective and time-efficient may have to compromise on specificity, with sensitivity favored because you don't want to miss any carriers, so we're at risk to see false positives.

In other words, if a bunch of dive tourists hit a destination, there's a decent chance somebody's going to get a false positive going or coming. That may affect them, and those known to have been in close quarters with them (e.g.: fellow live-aboard passengers). Which can mean travel delays and quarantine.

Naturally a key focus in this discussion has been concern people with the coronavirus will slip through testing. I'm afraid too many people without it won't.

 

[Ukmc]

Can I play again? Let’s say the test is 90% sensitive and the disease is 10% in prevalence. That means there is a 10% chance of marking a person who is positive as negative, or 10% of 10%, so negative predictive value is 99%. That’s pretty good. Let’s let 25 people on board including crew. 0.99 to the 25th power is 0.78, so there’s a 78% chance your tested bubble is a real bubble, so a 22% chance that at least one person on board is infected. I’ve been vaccinated with presumed 95% effectiveness against symptomatic infection, so that works out to about an end 1% chance I would get sick, and essentially 0% chance of being sick enough to require hospitalization. I would take that chance, but only because I got the vaccine, not because they are doing testing.

Great math! You need to add transmissibility of disease to you calculations. Specifically , infectiousness of someone with false negative test.

 

[Jcp2]

Great math. You need to add transmissibility of disease to you calculations. Specifically , infectiousness of someone with false negative test.

I think that’s hard to do because other behaviors add or subtract to transmissibility. We know that talking loudly, singing, and other things that add to heavier breathing lead to persistent aerosols, leading to superspreader events. The vaccines were not tested under the condition of normal pre covid behavior. Everybody was likely doing some sort of behavior modification, and because they were volunteers who believed in the severity of the disease enough to volunteer, likely social distancing more stringently than the general population. So take a group of adventurous individuals, give them the false security of no disease based on testing, not testing after strict quarantine and lack of symptoms, don’t require masks because of the illusion of a bubble, and let’s see how many can resist superspreader behavior. I say many would not be able to. Granted most of them would not be infected, but all it would take is that unknown 1/20 who is on board infected but not knowing it to not knowingly be a bit too exuberant because of the relief of going away for fun, and then poof! The bubble is popped.
In fact, when I go out, I’m not worried about the older person who is out and about. They probably don’t have COVID, as they probably would feel ill if they did. I worry about the younger person, because they can be infectious and not feel sick at all. Given that demographic, on a LOB, it’s the crew or non grey haired diver that’s the vector risk.