As for those rapid tests: the two antigen tests listed should both detect SARS-CoV-2. The three genetic tests listed (Meridian, Tide, Applied DNA) probably do not. As the FDA acknowledges, these were not tested on actual patient samples and the results are preliminary.
So, how useful is the rapid test I'm literally going to take after I hit "Post"? I have no way to know, because it's OraSure's IntelliSwab test. However, if the two other antigen tests still probably work, I'm at least cautiously encouraged.
Note for the peanut gallery: I'm one of the people who was exposed to our host. So far, no symptoms and negative test. Mind you, I was also wearing a high-quality filter mask. (I was exposed to another known case maskless, but with social distancing--we ate dinner together. That's one reason I'm quarantining until my PCR test result comes in, or 14 days since the last day of the convention. I can't even get PCR tested until a week from Sunday.)
Since it's a nucleocapsid antigen test it is probably pretty good at detecting Omicron still, but there remain some open questions about test sensitivity. I have heard people advocating that a throat swab should become part of the protocol too with this variant; I can't comment on that.
What I do know is that my nasal swabbing has been collecting enough antigen to turn a BinaxNOW positive. So there's that at least.
Because I hate being wrong: I get tested Wednesday. Because I'm not high priority (being asymptomatic) and given the current crush for testing, I was not promised my *results* before Sunday. Probably sooner, but not guaranteed.
In the beginning, it was save the N95s for medical personnel, but surgical masks and cloth masks were good. When N95s became more available, it was that they were best, followed by surgical, but cloth were still good (correct me if I'm wrong about this). Now, I am hearing to wear an N95, or a surgical mask if you can't get an N95, but nothing about cloth masks. Are they no longer considered protective? What changed?
Carl has mostly answered this, but really we've just learned more about how effective each intervention is. Various studies have shown an advantage for surgical masks over cloth and for high-standard masks like N95s over everything else. This isn't just Omicron-specific.
However, if Omicron is really more infective then it is possible we will need better masks to deal with it. This will be hard to determine definitively, but N95s are now cheap and more widely available than at the start of the pandemic, and it has also become apparent that you can wear the same N95 consistently for quite a long time before its filtration is compromised, so it has become a lot more feasible to deploy them for wide use. With that being the case, we might as well be on the safer side and use them preferentially.
N95s are cheap now (comparatively). They provide excellent protection, and you aren't depriving medical workers or first responders if you use them. I personally use KF94 masks, the South Korean equivalent, mostly because I have some and they fit me pretty well.
Cloth masks also suffer from linting. What I mean is, every time you wash them, they become less effective as threads move and come off. Most manufacturers I have seen say to wash no more than three times before discarding (but I'm sure every one is different).
CDC has also recommended using a surgical-type mask with a tight cloth mask over it (to seal it better to your face). I saw one person at DisCon III wearing two surgical masks, one over the other. This is NOT recommended. One downside of double-masking (which I have done): it is much harder to breathe through the two masks than through any type of respirator.
Carl, do you have any advice for getting a good fit with a respirator? I know hospital workers generally get professionally fit-tested, but I don't know of anywhere that just anybody off the street can go to get one done.
I've tried several different styles, and follow the instructions closely, but all fog up my glasses when I'm testing the seal. I've read that this may indicate a poor seal, but not necessarily. How do I know? (I have an aquiline nose, but surely that can't be respirator-disqualifying...)
We could invent a "dispersed saccharine" test for home use, similar to what NIOSH does for N95 certification.
The advice I follow is basically: put it on. Use your hand to mold the nose wire to your nose. Put your hands to "frame" the edge of the mask and breathe out forcefully. If no air escapes around the edge, good. if some does, tighten the straps. After you pass that one, inhale strongly (but not some overdramatic gasp) while looking in the mirror. If the mask seems to pull inward, you probably have a good seal.
The important reagent here is the extraction buffer included in the test. In, for example, the BinaxNOW test, the reagent buffer contains 0.0125% sodium azide. Sodium azide is biocidal and is used in many medical and laboratory preparations (ones that are not intended for human consumption) as a preservative because it destroys microbes. In the rapid test buffers it is present in quantities substantially below recommended exposure limits for humans, as a preservative. However, you should absolutely not consume, ingest, or otherwise misuse any part of a rapid antigen test. This may sound silly to state out loud but when safety is concerned it never hurts to spell it out. Use the test reagents exactly as they are recommended for use.
In the environment, sodium azide will rapidly disperse in soil to even lower concentrations beyond the initial low amounts. I do not foresee a disposal issue or chemical hazard in that regard.
Re:biohazard nature, the extraction buffer in the test, which as mentioned is what contains sodium azide, is intended to destroy virus particles to extract the nucleoprotein so that it can be detected via the test. I am going to look for confirmation on whether the degree of particle destruction is sufficient to render the sample safe, and I will update here with a subsequent comment when I learn more.
Per instructions on the test, it can be disposed in regular trash. The box and some packaging can be recycled but the test card should not be recycled.
SARS-CoV-2 can only survive in the environment for a limited period of time, anyway. After a day or so anything in such samples should be inert even if the buffer does not totally inactivate it within the test duration.
Personally I would be more concerned about any tissues that a patient might blow their nose into as biohazards, or a number of other products that a patient interacts with. Probably a good idea in general not to handle the household trash of people with COVID-19 unless one has appropriate PPE.
First and foremost--don't eat the tests! Or breathe them in, or stick them in your eyes :)
But if it makes you feel any better, EDTA tetrasodium is found at much higher concentrations in many cosmetics and human hygiene products that people apply directly to their skin; it's safe in those concentrations too.
Sodium phosphates of all varieties are used routinely in food--again in larger amounts--and are non-toxic in those concentrations as well. They are also used in very high concentrations in ingested preparations taken before colonoscopy. So far, nothing really to worry about here.
C12-14-Alkylmethyl-betaines are also found in cosmetics and personal care products. They have a lot of applications but again, we know their safe tolerance levels.
ProClin 300 is a preservative similar to sodium azide. It might actually be the most dangerous thing here. But, we know we shouldn't do anything with these tests that the testing manual doesn't call for. I've used the Quidel test and you don't have to touch any of the reagents. It has a higher false positive rate than the BinaxNOW, but its instructions were easy and the reagent comes in a prefilled tube so you don't have you really interact with it physically at all.
Sodium phosphate in all its variations is remarkably unhazardous. We are made of phosphates (literally, our bones are stiffened by calcium phosphate crystals) and everything we eat (that includes cells) contains phosphates.
EDTA, which you're saying can damage organs on exposure, is a very common food additive. It seems very unlikely to be present in large enough quantities to be harmful in waste disposal, given how little liquid is used in a test. (No azides, either.)
Thanks for the reply. The disposed masks litter everywhere you look. An issue I have been following about the American white tailed deer infected with SARS-Cov2 seems to point to deer in San Diego, CA becoming infected from bait, not from an airborne source. We know that direct sunlight can render it inert in 90 seconds, but what about in a contaminated pile of corn? Sewage wastewater monitoring reveals that it contains intact viral particles with very little information on if this can become a route of transmission, if not through the reclaimed water, possibly through the solid waste.
I've seen RNA collected from wastewater but never intact infectious virus--this maybe for lack of looking. Do you have a source confirming that?
Also I'm very interested in the source for deer becoming infected from bait. I have been really very curious how that might have happened and would like to read more about it. Would love some links on this.
I was under the impression that infection via the gut was still theoretical only and could not (in humans) be an important factor. Note: before omicron. If the tentative idea that omicron causes more throat problems turns out to be correct, maybe it's better at infecting gut epithelium?
Presumably they are using it in its pure form, before it's exposed to any sewage. I've also heard that aviation-grade oxygen has been considered for diversion for hospital use in some cases. It's all about whether the purity standard for medical settings is met.
According to the documentation for the antigen test I just took (OraSure IntelliSwab), the solution is just buffered saline with an antimicrobial and a surfactant. No azides.
You do dispose of a small amount of plastic (maybe 50g) with each test.
The test you have is a SARS-CoV-2 nucleocapsid protein antigen test and must contain a substance which bursts apart the virus to expose the nuclear protein. I have not seen it directly listed however.
I presume it's the surfactant included, According to the maker's web site, "Triton™ X-100 is a common non-ionic surfactant and emulsifier which is often used in biochemical applications to solubilize proteins. It is considered a comparatively mild detergent, non-denaturing, and is reported in numerous references as a routinely added reagent. It is utilized for lysing cells to extract protein and cellular organelles. It can also permeabilize the living cell membrane for transfection."
I think it's a mistake to say that vaccines are "for" only their clinical trial endpoint. At least prior to delta, for low-risk people who are able to work remotely and avoid human contact, the main draw *was* to make human contact ethically permissible by reducing the risk of transmission. As a fairly healthy 30-something I don't want to get sick, but what really matters is not being part of a chain that infects my friend's newborn baby and elderly parents.
Now I agree: vaccines are clearly inadequate for this purpose. But this greatly reduces their value! Not to zero or even close, but they used to allow human contact and now they don't (unless you embrace a "let it burn, the vulnerable should protect themselves" view). And that's a big deal.
I could be very literalist and say "the reason it's the primary endpoint is that that's what the product was designed to do," but I think you'd find that unsatisfying.
I agree that it is highly attractive for the vaccine to prevent transmission, no argument from me. However, it's also highly attractive for it to stop people from becoming hospitalized or dying. Sure, you cannot be certain you won't give your relatives COVID-19, but you're going to feel a lot better if you do accidentally give them COVID-19 and they survive uninjured.
There are many viruses that cause mild illnesses, against which we have no vaccines. I imagine you do not worry very much about transmitting these, or perhaps you did not before the pandemic. I do not think we should avoid in-person interactions over circulating common cold coronaviruses.
No vaccine is going to deliver a reality where young children and the elderly never get sick, and that shouldn't be the goal, because it is unrealistic. The goal should be that when they get sick, it's very mild or even totally asymptomatic, and they recover readily.
If we can reduce the risk of death or disability from COVID-19 to a tiny fraction of what it was last March, using vaccines, we have an actual opportunity to return to a basically normal life where you can see family and friends in person and be more worried about getting into a car accident on the way there than about killing them with a coronavirus.
Feel better, man!
As for those rapid tests: the two antigen tests listed should both detect SARS-CoV-2. The three genetic tests listed (Meridian, Tide, Applied DNA) probably do not. As the FDA acknowledges, these were not tested on actual patient samples and the results are preliminary.
So, how useful is the rapid test I'm literally going to take after I hit "Post"? I have no way to know, because it's OraSure's IntelliSwab test. However, if the two other antigen tests still probably work, I'm at least cautiously encouraged.
Note for the peanut gallery: I'm one of the people who was exposed to our host. So far, no symptoms and negative test. Mind you, I was also wearing a high-quality filter mask. (I was exposed to another known case maskless, but with social distancing--we ate dinner together. That's one reason I'm quarantining until my PCR test result comes in, or 14 days since the last day of the convention. I can't even get PCR tested until a week from Sunday.)
Since it's a nucleocapsid antigen test it is probably pretty good at detecting Omicron still, but there remain some open questions about test sensitivity. I have heard people advocating that a throat swab should become part of the protocol too with this variant; I can't comment on that.
What I do know is that my nasal swabbing has been collecting enough antigen to turn a BinaxNOW positive. So there's that at least.
Because I hate being wrong: I get tested Wednesday. Because I'm not high priority (being asymptomatic) and given the current crush for testing, I was not promised my *results* before Sunday. Probably sooner, but not guaranteed.
John, sorry to hear you came down with COVID, but glad you're holding up well.
Thanks Sam!
Question about masking.
In the beginning, it was save the N95s for medical personnel, but surgical masks and cloth masks were good. When N95s became more available, it was that they were best, followed by surgical, but cloth were still good (correct me if I'm wrong about this). Now, I am hearing to wear an N95, or a surgical mask if you can't get an N95, but nothing about cloth masks. Are they no longer considered protective? What changed?
Carl has mostly answered this, but really we've just learned more about how effective each intervention is. Various studies have shown an advantage for surgical masks over cloth and for high-standard masks like N95s over everything else. This isn't just Omicron-specific.
However, if Omicron is really more infective then it is possible we will need better masks to deal with it. This will be hard to determine definitively, but N95s are now cheap and more widely available than at the start of the pandemic, and it has also become apparent that you can wear the same N95 consistently for quite a long time before its filtration is compromised, so it has become a lot more feasible to deploy them for wide use. With that being the case, we might as well be on the safer side and use them preferentially.
Not an expert, but I know some.
N95s are cheap now (comparatively). They provide excellent protection, and you aren't depriving medical workers or first responders if you use them. I personally use KF94 masks, the South Korean equivalent, mostly because I have some and they fit me pretty well.
Consumer Reports (https://www.consumerreports.org/face-coverings/use-a-better-mask-covid-19-a2629884110/) offers fairly typical advice: cloth masks are better than nothing. Surgical-style masks are better than those. Actual respirators (technically what N95, KF94, or KN95 devices are) are still better.
Cloth masks also suffer from linting. What I mean is, every time you wash them, they become less effective as threads move and come off. Most manufacturers I have seen say to wash no more than three times before discarding (but I'm sure every one is different).
CDC has also recommended using a surgical-type mask with a tight cloth mask over it (to seal it better to your face). I saw one person at DisCon III wearing two surgical masks, one over the other. This is NOT recommended. One downside of double-masking (which I have done): it is much harder to breathe through the two masks than through any type of respirator.
Note that the CDC reports about 60% of KN95 (Chinese standard) masks sold in the USA are counterfeits. There are also counterfeit N95s out there. The CDC has a page on that: https://www.cdc.gov/niosh/npptl/usernotices/counterfeitResp.html
They also have tips on spotting counterfeits:
https://www.cdc.gov/niosh/npptl/usernotices/AdditionalTips.html
Carl, do you have any advice for getting a good fit with a respirator? I know hospital workers generally get professionally fit-tested, but I don't know of anywhere that just anybody off the street can go to get one done.
I've tried several different styles, and follow the instructions closely, but all fog up my glasses when I'm testing the seal. I've read that this may indicate a poor seal, but not necessarily. How do I know? (I have an aquiline nose, but surely that can't be respirator-disqualifying...)
This may be too basic for you at this point, but here is a donning guide video for an N95: https://www.cdc.gov/vhf/ebola/hcp/ppe-training/n95respirator_gown/donning_09.html
I've wondered if I could get fit-testing done as well. Ultimately I think it may be too onerous to perform regularly enough.
We could invent a "dispersed saccharine" test for home use, similar to what NIOSH does for N95 certification.
The advice I follow is basically: put it on. Use your hand to mold the nose wire to your nose. Put your hands to "frame" the edge of the mask and breathe out forcefully. If no air escapes around the edge, good. if some does, tighten the straps. After you pass that one, inhale strongly (but not some overdramatic gasp) while looking in the mirror. If the mask seems to pull inward, you probably have a good seal.
Here's a recent Twitter thread from a doc on DIY fit-testing: https://twitter.com/jenniferkshea/status/1472417124048064519?s=21. Better than nothing, I suppose.
Thank you. That makes sense. I was wondering if it was something specific to omicron. Sounds like that's not the case.
Where do all of these at home tests loaded with biohazards and sodium azide wind up? Seious question...
I think this is a very fair question.
The important reagent here is the extraction buffer included in the test. In, for example, the BinaxNOW test, the reagent buffer contains 0.0125% sodium azide. Sodium azide is biocidal and is used in many medical and laboratory preparations (ones that are not intended for human consumption) as a preservative because it destroys microbes. In the rapid test buffers it is present in quantities substantially below recommended exposure limits for humans, as a preservative. However, you should absolutely not consume, ingest, or otherwise misuse any part of a rapid antigen test. This may sound silly to state out loud but when safety is concerned it never hurts to spell it out. Use the test reagents exactly as they are recommended for use.
In the environment, sodium azide will rapidly disperse in soil to even lower concentrations beyond the initial low amounts. I do not foresee a disposal issue or chemical hazard in that regard.
Re:biohazard nature, the extraction buffer in the test, which as mentioned is what contains sodium azide, is intended to destroy virus particles to extract the nucleoprotein so that it can be detected via the test. I am going to look for confirmation on whether the degree of particle destruction is sufficient to render the sample safe, and I will update here with a subsequent comment when I learn more.
Per instructions on the test, it can be disposed in regular trash. The box and some packaging can be recycled but the test card should not be recycled.
SARS-CoV-2 can only survive in the environment for a limited period of time, anyway. After a day or so anything in such samples should be inert even if the buffer does not totally inactivate it within the test duration.
Personally I would be more concerned about any tissues that a patient might blow their nose into as biohazards, or a number of other products that a patient interacts with. Probably a good idea in general not to handle the household trash of people with COVID-19 unless one has appropriate PPE.
Here is the list of hazardous ingredients for the Quidel QuickVue test:
Sodium Phosphate Monobasic Monohydrate .7%, Sodium Phosphate Dibasic Anhydrous .7%, C12-14-Alkylmethyl-betaines .03%, ProClin 300 (SigmaAldrich) .03%, EDTA tetrasodium salt .2%, sounds delicious! Eye, skin, lung irritants, the last ingredient can damage organs on single exposure.
First and foremost--don't eat the tests! Or breathe them in, or stick them in your eyes :)
But if it makes you feel any better, EDTA tetrasodium is found at much higher concentrations in many cosmetics and human hygiene products that people apply directly to their skin; it's safe in those concentrations too.
Sodium phosphates of all varieties are used routinely in food--again in larger amounts--and are non-toxic in those concentrations as well. They are also used in very high concentrations in ingested preparations taken before colonoscopy. So far, nothing really to worry about here.
C12-14-Alkylmethyl-betaines are also found in cosmetics and personal care products. They have a lot of applications but again, we know their safe tolerance levels.
ProClin 300 is a preservative similar to sodium azide. It might actually be the most dangerous thing here. But, we know we shouldn't do anything with these tests that the testing manual doesn't call for. I've used the Quidel test and you don't have to touch any of the reagents. It has a higher false positive rate than the BinaxNOW, but its instructions were easy and the reagent comes in a prefilled tube so you don't have you really interact with it physically at all.
Sodium phosphate in all its variations is remarkably unhazardous. We are made of phosphates (literally, our bones are stiffened by calcium phosphate crystals) and everything we eat (that includes cells) contains phosphates.
EDTA, which you're saying can damage organs on exposure, is a very common food additive. It seems very unlikely to be present in large enough quantities to be harmful in waste disposal, given how little liquid is used in a test. (No azides, either.)
Thanks for the reply. The disposed masks litter everywhere you look. An issue I have been following about the American white tailed deer infected with SARS-Cov2 seems to point to deer in San Diego, CA becoming infected from bait, not from an airborne source. We know that direct sunlight can render it inert in 90 seconds, but what about in a contaminated pile of corn? Sewage wastewater monitoring reveals that it contains intact viral particles with very little information on if this can become a route of transmission, if not through the reclaimed water, possibly through the solid waste.
I've seen RNA collected from wastewater but never intact infectious virus--this maybe for lack of looking. Do you have a source confirming that?
Also I'm very interested in the source for deer becoming infected from bait. I have been really very curious how that might have happened and would like to read more about it. Would love some links on this.
I was under the impression that infection via the gut was still theoretical only and could not (in humans) be an important factor. Note: before omicron. If the tentative idea that omicron causes more throat problems turns out to be correct, maybe it's better at infecting gut epithelium?
Saw a report that in Florida oxygen used to treat raw sewage was being diverted for hospital use.
Presumably they are using it in its pure form, before it's exposed to any sewage. I've also heard that aviation-grade oxygen has been considered for diversion for hospital use in some cases. It's all about whether the purity standard for medical settings is met.
According to the documentation for the antigen test I just took (OraSure IntelliSwab), the solution is just buffered saline with an antimicrobial and a surfactant. No azides.
You do dispose of a small amount of plastic (maybe 50g) with each test.
https://www.fda.gov/media/149911/download
Read Johns reply.
I have. He was talking about a different test.
The test you have is a SARS-CoV-2 nucleocapsid protein antigen test and must contain a substance which bursts apart the virus to expose the nuclear protein. I have not seen it directly listed however.
I presume it's the surfactant included, According to the maker's web site, "Triton™ X-100 is a common non-ionic surfactant and emulsifier which is often used in biochemical applications to solubilize proteins. It is considered a comparatively mild detergent, non-denaturing, and is reported in numerous references as a routinely added reagent. It is utilized for lysing cells to extract protein and cellular organelles. It can also permeabilize the living cell membrane for transfection."
https://www.sigmaaldrich.com/US/en/product/sial/x100
I speculate that the azide performs a similar function in other antigen tests.
TY! I'm anxious to see John's report concerning if "the degree of particle destruction is sufficient to render the sample safe".
I know there is one home rapid test that talks to a smartphone and has electronica involved, but i don't know much more about it.
Since the antigen tests are pretty much the same technology as pregnancy tests, this tactile solution would be technically possible but probably not at all scalable and I don't think it is on the market for pregnancy tests either: https://www-wsj-com.cdn.ampproject.org/v/s/www.wsj.com/amp/articles/prototype-device-lets-blind-women-take-pregnancy-tests-in-privacy-11603295080?
[WSJ, surprisingly not paywalled]
(that was the first hit for blind accessible pregnancy, but it looks like there's been more written a little more recently)
רפואה שלמה
Thank you, Iris!
I think it's a mistake to say that vaccines are "for" only their clinical trial endpoint. At least prior to delta, for low-risk people who are able to work remotely and avoid human contact, the main draw *was* to make human contact ethically permissible by reducing the risk of transmission. As a fairly healthy 30-something I don't want to get sick, but what really matters is not being part of a chain that infects my friend's newborn baby and elderly parents.
Now I agree: vaccines are clearly inadequate for this purpose. But this greatly reduces their value! Not to zero or even close, but they used to allow human contact and now they don't (unless you embrace a "let it burn, the vulnerable should protect themselves" view). And that's a big deal.
I could be very literalist and say "the reason it's the primary endpoint is that that's what the product was designed to do," but I think you'd find that unsatisfying.
I agree that it is highly attractive for the vaccine to prevent transmission, no argument from me. However, it's also highly attractive for it to stop people from becoming hospitalized or dying. Sure, you cannot be certain you won't give your relatives COVID-19, but you're going to feel a lot better if you do accidentally give them COVID-19 and they survive uninjured.
There are many viruses that cause mild illnesses, against which we have no vaccines. I imagine you do not worry very much about transmitting these, or perhaps you did not before the pandemic. I do not think we should avoid in-person interactions over circulating common cold coronaviruses.
No vaccine is going to deliver a reality where young children and the elderly never get sick, and that shouldn't be the goal, because it is unrealistic. The goal should be that when they get sick, it's very mild or even totally asymptomatic, and they recover readily.
If we can reduce the risk of death or disability from COVID-19 to a tiny fraction of what it was last March, using vaccines, we have an actual opportunity to return to a basically normal life where you can see family and friends in person and be more worried about getting into a car accident on the way there than about killing them with a coronavirus.