Baylor AD suspects COVID outbreak in FB team likely due to false negative test result(s)
Surprised this hasn't been discussed more, but the outbreak at Baylor (that resulted in this week's game against Ok State getting postponed) is "likely" due to one or two false negative tests - allowing a highly infectious person to travel with the team to their game at WVU, per their AD.
The likely false negative(s) was in their rapid antigen daily testing, not the longer (but more accurate) PCR tests. I was under the impression that the rapid tests were being so heavily relied upon since they were more likely to be false positive than false negative (with the PCR test to confirm if rapid positive cases were false or not).
If false negatives are more pervasive than expected, this might be cause for schools to reevaluate their protocols.
October 14th, 2020 at 10:35 AM ^
I read the OP title too quickly and thought the narrative was exactly the opposite, that the Baylor AD was pissed that they had an imaginary outbreak due to rapid test false positives. After reading the OP and title more carefully, I discovered that my first impression was very wrong. I also thought that false negatives were not the issue with rapid tests.
I am hopeful that Sopwith will respond in this thread with words of scientific and statistical wisdom, sprinkled with his/her usual humor and levity.
October 14th, 2020 at 11:05 AM ^
You rang? He/Him will do nicely, thanks.
Seriously though, this has been an issue all along, particularly with asymptomatic people. Neither of the respective Emergency Use Authorizations (EUAs) for both the Quidel (LINK) and Abbott (LINK) rapid antigen tests authorize for use in asymptomatic individuals, which is the real problem here.
For example, the Abbott test's EUA specifically notes that it probably shouldn't be used for asymptomatic detection, certainly not in the absence of other confirmatory protocols:
Negative results from patients with symptom onset beyond seven days, should be treated as presumptive and confirmation with a molecular assay, if necessary, for patient management, may be performed. Negative results do not rule out SARS-CoV-2 infection and should not be used as the sole basis for treatment or patient management decisions, including infection control decisions.
That's probably because the EUA was based on a very limited testing pool, and the few asymptomatic patients who were tested mostly slipped under the radar unless tested via PCR. This article in the Atlantic last week highlights some of the concerns in the industry vis-a-vis rapid testing:
The new Abbott test, the Binax NOW, received an emergency use authorization (EUA) based on results from just 102 samples. The next day, the government spent $760 million to buy the entire supply of tests. Notably, the FDA did not support the use of the test for screening asymptomatic people—which the most ambitious version of [Harvard Epidemiologist Michael] Mina's plan [for widespread national testing] depends on. The emergency use authorization only covered testing for people within the first seven days of developing symptoms, when viral loads remain high.
Likewise, the FDA announcement for Quidel's EUA lays it out pretty clearly:
However, antigen tests may not detect all active infections, as they do not work the same way as a PCR test. Antigen tests are very specific for the virus, but are not as sensitive as molecular PCR tests. This means that positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection. With this in mind, negative results from an antigen test may need to be confirmed with a PCR test prior to making treatment decisions or to prevent the possible spread of the virus due to a false negative.
Which leads to collar-tugging concerns like this from the testing gurus:
“The point I'm trying to make here, and I'll be blunt, is that antigen testing will not and cannot work for asymptomatic screening, and [it] will probably kill a lot of people,” Geoffrey Baird, the acting laboratory-medicine chair at the University of Washington, told us. His lab at UW developed one of the earliest accurate COVID-19 tests in the U.S., and is widely respected within the diagnostic-testing field. Alexander McAdam, the director of the infectious-diseases diagnostic laboratory at Boston Children’s Hospital, told The New York Times that deploying the current antigen tests to screen populations “is a bad idea, and I’ll die on that hill.”
All of which suggests the over-reliance on rapid antigen screening was asking for trouble from the beginning. Tweets soon after the decision to reverse course and start the B1G were accompanied by many talking head quotes along the lines of "the tests will detect infected individuals before they are infectious," which never cited any medical authority, they just echoed in the Twitterverse. I'm still looking for that in the literature more than a month later and can't find support for it.
Generally, looking at the stats provided, false negatives for properly performed tests on symptomatic individuals are pretty unusual, around 1-2%. The hitch there might be "properly performed." For example, the Abbott test requires adequate rotation of the swab sample when applying to the test card. The EUA notes right there on page 5: "Note: False negative results can occur if the sample swab is not rotated (twirled) prior to closing the card."
So don't forget to twirl, I guess?
October 14th, 2020 at 11:29 AM ^
I am a well-educated individual, but still find it difficult to disseminate relevant covid-related testing issues. This is exactly the information I/we needed.
You are an obvious font of knowledge, but it's your ability to help us wade through the morass of noise and overt disinformation with practical science-based information that impresses me most.
Infinite drinks are on me at a happy hour location of your choice after we get past the covid issues.
You also didn't disappoint with the levity and humor. I set you up for what could have been an epic fail. Well done.
/Faints in true fanboy fashion
October 14th, 2020 at 11:30 AM ^
So basically if you are sick these tests will tell you if you have Covid or not. Well, if you are sick with Covid or just a cold STAY THE F*** AWAY FROM EVERYBODY!!!! No testing required.
October 14th, 2020 at 11:34 AM ^
Huh? How does this relate to using rapid antigen tests for testing football players multiple times per week when there are scientifically-noted reasons to be somewhat wary of using said tests for such purposes?
EDIT: Maceo's response below seems to interpret the above comment better than I could!
October 14th, 2020 at 11:48 AM ^
I guess it says that we can save the institutions a lot of time and money by not testing. If this test is best used to find symptomatic people you don’t have to test. If you are sick stay home.
now if you want to test the teams and prevent outbreaks as the press and conference seems to indicate is the plan …. You will need to find a new test method and you have about a week to get it figured out.
October 14th, 2020 at 12:04 PM ^
i think the real problem (as all of us who have children going to any kind of school or daycare) is that any symptom of anything can be a covid symptom. so what's the definition of asymptomatic? literally the state of michigan guidance right now is if a child has a runny nose, that's a symptom. slight headache? symptom. have a weird poop? symptom.
so, there's some benefit to the daily testing to try to triage against these early symptoms that could be anything.
October 14th, 2020 at 2:33 PM ^
Agree so much with this. Our kids play soccer and have to fill out a daily health check that asked if you are exhibiting any of 5-6 conditions. But then has a caveat that they don’t count if they are attributable to a known medical condition. We check “no” because our kids have allergies that are a disaster in the fall. But I have no true way of knowing if the sore throat and runny nose are because of ragweed or Covid.
October 14th, 2020 at 11:40 AM ^
I remember seeing that same line out of big ten official(s) about the antigen testing catching people before they were infectious, and to this lay person, it didn't make sense. Interesting that you have searched for support and not been able to find any.
To me, the "game changing" element of the antigen tests was to be able to use them daily, making up somewhat for the lower reliability. However, if they really are only reliable at all in symptomatic individuals, not sure this is an improvement at all from regular PCR testing. At this point I am expecting at least one Big Ten team to have a large outbreak due to over reliance on the testing regime leading to slacking in behavioral prevention of covid spread.
October 14th, 2020 at 1:39 PM ^
Daily testing is the strategy the White House used, and we all know how that turned out. Daily testing doesn't help if one continues to engage in risky behavior. Tests can't prevent, they might be able to limit the spread.
October 14th, 2020 at 11:47 AM ^
Thanks for the pertinent info.
Did I miss Part IV on the immunology course by Sopwith, or is it not finished? I would love to read it.
Thanks.
October 14th, 2020 at 2:20 PM ^
Yeah Part IV is the "Treatments and Vaccines" section, but I was holding it up waiting for the Phase III clinical trial data to roll in on some of the big names this fall.
I'll probably end up just running with a current look at treatments in the next couple weeks and drop vaccines in a Part V late in the year.
October 14th, 2020 at 12:29 PM ^
I voted for Kodos
October 14th, 2020 at 2:42 PM ^
Wow. Clear. Cogent. Information rather than snark. Are you sure you're an MGoBlogger?
P.S. Who do you sop with?
October 14th, 2020 at 10:39 AM ^
Make you wonder what their testing protocol is. Daily -probably not. Weekly? Monthly?
October 14th, 2020 at 10:44 AM ^
Three times per week, including the day before competition.
October 14th, 2020 at 12:05 PM ^
and twice on Sunday
October 14th, 2020 at 10:46 AM ^
Baylor, in accordance with Big 12 guidelines, tests athletes and staff members three times per week. Two of those tests are PCR, Rhoades said, and the third test, prior to games, is an antigen test.
October 14th, 2020 at 11:23 AM ^
Michigan is doing daily antigen testing as I recall. More accurate but results are delayed?
October 14th, 2020 at 11:43 AM ^
Actually the opposite. Less accurate but faster and more often.
October 14th, 2020 at 10:40 AM ^
I use one of the rapid tests in my office and the manufacturer claims sensitivity and specificity rates of 87 and 100% respectively so false negatives are clearly an issue. This is the trade off when you want quick results.
October 14th, 2020 at 11:36 AM ^
Absolutely no way the test has 100% specificity rate. That means there are ZERO false negatives.
October 14th, 2020 at 1:05 PM ^
Actually it means that there are zero false positives.
October 14th, 2020 at 1:39 PM ^
Thank you-I thought that was understood.
October 14th, 2020 at 10:50 AM ^
Damn that really sucks
October 14th, 2020 at 10:51 AM ^
As I understand is the point of daily rapid testing is that even if you get a false negative you likely catch it because of the more frequent testing. e.g. Wednesday’s false negative is caught by Thursday’s test. Doesn’t work for last test before traveling but wouldn’t work for PCR testing because you couldn’t turn around results quick enough.
October 14th, 2020 at 12:07 PM ^
They could have set up on campus PCR testing and gotten results back in 2 hours.
October 14th, 2020 at 12:38 PM ^
This. Any university offering biology-related majors should be able to handle PCRs no problem. Speaking from experience
October 14th, 2020 at 6:04 PM ^
issue is others need to use them, not just for covid.
October 14th, 2020 at 12:50 PM ^
Correct. If you're testing more frequently it really limits the impact.
Scenario 1: 13% chance of false negative and tested twice before game day = 1.69% chance of an infected person traveling with the team believing they're healthy.
Scenario 2: 13% chance of false negative tested daily 4 times before game day: 0.03% chance of 4 false negatives in a row and an infected person traveling with the team believing they're healthy.
October 14th, 2020 at 1:08 PM ^
I guess the question I would have is whether false negatives with the same test method on the same person are “random” events? In other words is the infection response in some people more likely to induce a false negative (less virus in saliva for example). I have no idea, but that would change your math.
October 14th, 2020 at 1:11 PM ^
I'm not sure that is the proper comparison. It isn't about continuing to test negative all week when you're really positive. It's about the fastest way to catch a positive test once a player has become infected. If a player becomes infectious on Thursday but is still asymptomatic through Friday, the question is what testing procedure will catch a positive by travel on Friday. I understand PCR testing should catch it and obviously if there is no testing on Thursday or Friday, it won't be caught. The question becomes whether a rapid antigen test will catch the asymptomatic but contagious case, and my understanding is that it is unlikely.
Daily antigen testing can certainly be useful, but it still needs to be part of a total game plan involving distancing, masks, cohorts, PCR testing, etc. My concern from the language of various big 10 people is that this has been lost and the rapid antigen test is enough to show you have a "clean" environment. That's a dangerous assumption that seems likely to bite at least one big ten team this year.
October 14th, 2020 at 10:53 AM ^
Where I live, the health care providers who offer rapid testing have put disclaimers up that they're seeing about 85ish% agreeement between the PCR tests and the rapid tests.
Which means that the possibility for false negatives/positives is there. I wouldn't be surprised if things were improving as scientists learn more, but operationalizing advancements in knowledge takes time.
When I last got tested, they administered both just in case.
October 14th, 2020 at 10:57 AM ^
Numbers are ramping up again in my hospital. It's really going to be interesting to see how this pans out. False negatives, etc... I'm not sure any of it is going to matter. Roller coaster is climbing up the hill again.
October 14th, 2020 at 11:02 AM ^
"...more likely to be false positive than false negative..."
This can still be the case without precluding a false negative. One may happen more often than the other, but that doesn't mean both will not happen.
October 14th, 2020 at 11:16 AM ^
False negatives are definitely an issue with the rapid result test.
October 14th, 2020 at 11:20 AM ^
Even if false negatives are unlikely, they're still possible, and situations like this, however unlikely, can still happen. It seems like it needs the worst-case stackup of a false negative happening just before travel, or multiple false negatives happening just before travel. Both are unlikely, but possible.
Not sure if there's any way to mitigate this.
October 14th, 2020 at 11:54 AM ^
Even in the best case scenario.... shit can happen
October 14th, 2020 at 12:44 PM ^
I am sure it is related to increase in ass eating and the transmission therein.
October 14th, 2020 at 12:50 PM ^
A small percentage of every setting (school, hospital, church, workplace) will eventually run into a super-spreader event--the key is surveillance (to be aware of an event early), system design to mitigate the effect of an event (e.g., cohorting classes etc.) and aggressive post-event containment, which can easily take three weeks and spread to a surprising # of people from just a single index case. And most importantly, making sure that the event/setting is worth the risk, which is the most subjective part of it all...
Just the nature of SARS-CoV-2: rather than a couple infections spread every time there is an exposure, it is often zero transmission many times in a row until a large super-spreader event. A different kind of approach required than, say, influenza.
October 14th, 2020 at 12:52 PM ^
If true, it doesn't surprise me this happened. Having experience in the Dx space, my opinion is that false negatives a typically more problematic than false positives.
For example, for HIV testing. As of 10 years ago (I haven't kept up on current testing protocols), they would give people the HIV antibody test. If it was positive, they would give an RNA/PCR test to confirm. If it was negative, you get a pat on the back on you're on your way. So a false negative for HIV can become an issue. That's why Dx development does what it takes to minimize false negatives (over false positives).
However, false negatives do happen from time to time and lead to what has happened at Baylor.
October 14th, 2020 at 4:20 PM ^
HIV testing had another issue, which is that the thing they were testing for was very rare - maybe 1 in 100000 samples would have the virus. In which case your math for a 99% accurate test looks like this.
1M samples:
999,990 virus free samples x 99% accurate test = 989990 correct negative results, 9999(!) false positives
100 virus-infected samples x 99% accurate test = 99 correct positives, 1 false negative
You can play with the rates, but the main point is that when the thing you're looking for is orders of magnitude more rare than the accuracy of the test, positive results are 100-1 likely to be false, and almost no negative tests are false.
The opposite is true for COVID. Let's say that the test is 90% accurate both ways, and that 5% of the samples are infected.
1M samples:
950000 virus-free samples x 90% accurate test = 855K correct negatives, and 95K false positives
50K virus-infected samples x 90% accurate test = 45K correct positives, and 5K false negatives
Now your positives are only 2-1 likely to be false, and correct positives are 9-1 to false negatives.
TLDR: Large numbers screw with our perception of math. Covid testing is tricky.
October 14th, 2020 at 1:00 PM ^
The key thing is that even though only 85% of infections are caught via quick tests, they are caught before people are infectious. With an estimated 10% of infections currently being caught by PCR testing according to the NIH, that is a huge win. Even those that are testing positive are infectious for days before they get their positive test back, so why bother? Apparently, most PCR tests are catching people who have already stopped being infectious.
So test everyone every day. Catch 85% of people before they are infectious rather than testing randomly and catching 10% of infections and most of those days after they have been infectious. Seems like an easy call for the general population. It would quickly damp down overall infection rates.
For sports teams, not so good. Catching 85% before infection still leaves 15% that are probably infectious for as much as 24 hours before getting retested (assuming daily testing). Oops.
October 14th, 2020 at 2:06 PM ^
I mean, none of this should surprise anyone. Rapid tests, even ones that trend toward false positives, are still going to miss positive cases sometimes, and if you're sort of performing them in a perfunctory way and your activities are not otherwise designed to really limit risk, they're just going to be CYA/window dressing for most people.
Combined with the Florida postponement and what's happening in the NFL it's pretty clear at this point that the season is going to have issues being completed in the timeframes they've set up for them.
October 14th, 2020 at 2:38 PM ^
Reevaluate? Only when forced to.
October 14th, 2020 at 3:50 PM ^
It's all the fault of those damn Neanderthals:
"Genetic variants that leave their carrier more susceptible to severe COVID-19 are inherited from Neanderthals, a new study finds."
https://www.sciencedaily.com/releases/2020/09/200930094758.htm
October 14th, 2020 at 7:49 PM ^
The antigen tests are about 85% sensitivity - so figure that’s 1 false negative per team per round of tests. Not ideal; but it’s still effective enough to try.