This is a great reminder of the basics, and I will implement when I can situationally. I think the value of asymptomatic rapid antigen testing has dropped pretty far (maybe 30% sensitivity?) but adds another layer of Swiss cheese protection. Ventilation is the best.
What do you think of nasal sprays like Enovid and Iota-Carrageenan? I wrote a post about this for my audience, do a free trial or I'll comp you for free if you'd like to read in its entirety!
Hi Ryan, Here's a post I wrote about Enovid for Those Nerdy Girls. Here's an excerpt from my post:
Enovid / VirX/ FabiSpray is a nitric oxide nasal spray that could be a promising addition to our COVID-fighting toolkit. Yet, it’s by no means a silver bullet, or a reason to forgo well-established precautions and treatments. Expect to use this nasal spray several times a day during high-risk exposures or during infection. These products are not yet approved in Canada or the US, but things may change next year when Phase 3 data become available.
What do you mean by asymptomatic rapid testing having 30% sensitivity? Does that mean rapid tests only test positive 30% of the time when someone is infected with Covid but is asymptomatic?
Here is another study out recently that I just read:
“They found that on PCR testing, median cycle threshold (Ct) values hit their lowest point -- which is consistent with peak viral load -- on the fourth day of symptoms.
Using Ct values to predict rapid antigen results, the researchers estimated a sensitivity of 30% to 60% on the first day of symptoms, rising to 80% to 93% on the fourth day of symptoms.
Early in the pandemic, they wrote, a single negative antigen test had "reasonable negative predictive value," with studies reporting 90% to 95% sensitivity in the first week of symptoms. Now, overall predicted sensitivity in the first week is about 60% to 80%, they said.”
Hi - 30% is a lowball estimate, but the Cochrane review on this puts the sensitivity of rapid tests in asymptomatic individuals who were found to have Covid either later or by PCR (pooled analysis of several studies) around 50%.
Average sensitivity was greater in those who had symptoms (73.0%; 95% CI, 69.3% to 76.4%; 109 evaluations; 50,574 samples; 11,662 confirmed SARSCoV-2 cases) vs. those without symptoms (54.7%; 95% CI, 47.7% to 61.6%; 50 evaluations; 40,956 samples; 2,641 confirmed SARS-CoV-2 cases)....
In patients who were asymptomatic at the time of testing, sensitivity was higher when epidemiologic exposure (i.e., contacts of patients with confirmed cases) to the SARSCoV-2 virus was suspected based on studies reporting specific criteria for testing or referral for testing in the absence of symptoms (64.3%; 95% CI, 54.6% to 73.0%; 16 evaluations; 7,677 samples; 703 cases). By contrast, when COVID-19 testing was reported to be widely available to any asymptomatic participant, sensitivity was lower (49.6%; 95% CI, 42.1% to 57.1%; 26 evaluations; 31,904 samples; 1,758 cases).
...
Sensitivity varied widely among brands. Average sensitivities by brand ranged from 34.3% to 91.3% in symptomatic participants (20 assays with eligible data) and from 28.6% to 77.8% in asymptomatic participants (12 assays).1
Thanks, Ryan. I recently wrote a post for Those Nerdy Girls on asymptomatic testing and wanted to build on the great info you have provided from Cochrane. I think it's really important to note that test timing and repeat testing are key (both for cases with and without symptoms). For example, the US Test at Home study reported that a single RAT worked best on Day 4 (Day 0 = first PCR positive). At this point, a single RAT caught 75% of asymptomatic cases. Performance is much lower if you test in the first couple days after exposure. This makes sense because levels of the virus typically peak around this time.
I really appreciate your practical advice. My family recently decided we were ready to go on a vacation for ten days. We flew. We stayed in a hotel. We ate from a buffet. AND we wore high-quality masks whenever we were indoors around other people, even for a minute, and we always ate outside. We met several lovely families doing the same due to many different reasons, including peanut allergies. We changed our paths to avoid people who were coughing when we could. There were plenty of them to avoid at the amusement park and zoo! It was hard to go without eating a proper meal in the airport and plane for six hours, but we did it! (We practiced the "hold your breath as you insert a big bite of granola bar before putting your mask back on" maneuver.) The trip was wonderful, and no one got sick. (And no one gave us funny looks or said a thing about our "odd" behavior that we know of.)
This was such a helpful, reasonable & human-centric approach to the realities of today’s (& tomorrow’s) decision-making regarding infection prevention. The fact that it is no longer stressed or even suggested just makes compliance that much more
challenging.
And the selfishness such silence condones is heartbreaking.
I know no one in our social groups or in our extended family who think about doing any of these things anymore, if they even ever did. But as a family with an immune-compromised member, we still have to make these considerations all the time. My husband and I weigh benefits/risks for every social situation we consider. People are shocked when I tell them I can’t attend a gathering because it’s indoors and for a meal and no one will be wearing masks. They look at us like we’re crazy. It’s just so frustrating when we are the ones always asking the questions about the details of an event. No one else considers limiting exposure to infection anymore.
Thank you for sharing your mental gymnastics. We see you and your continued balancing act. Those Nerdy Girls think about infection risks and tradeoffs. A lot. There is so much room in between doing nothing to reduce risks and avoiding all social contact. We are hopeful more people can navigate "the middle" with facts and empathy.
5 days after infection is not enough time for many to clear the virus. 2 negative tests 48 hours apart would be much safer criteria before attending an event.
Hi there, I just wanted to chime into this discussion as a Nerdy Girl who has been covering the testing "beat". The author (Ashley) was not suggesting that you would be negative by Day 5. She was suggesting that you are likely to get your first positive test by Day 2-5 after exposure. This is because takes a few days after exposure for the virus to reach sufficient levels to light up the test. The official recommendation for FDA/CDC is to wait 5 days after exposure before testing, to give the best chances of having enough virus to detect - and to re-test if negative. It's a different discussion with regards to how long it takes to clear the virus once you're positive. It's common to remain positive for 7-10 days after your first positive test - or longer!
Then, I suggest clarifying that on the article. She wrote, “If you have an infection prior to the event , you should wait 5 days from the start of symptoms before mingling with others.”
Hi! I thought you referring to when she said to test 2-5 days after the event to see if you picked up COVID! With regards to when it's okay to mingle, it's not black and white. Current guidance from CDC is to isolate for 5 days if you have symptoms, as this is when the vast majority of transmission happens. It's unclear how contagious people are after that, and the answer varies from person to person. It's not zero, but the risk does drop dramatically. We used to think that rapid tests were a great indicator of contagiousness, but I think it's increasingly unclear of how well viral levels in the nose represent the risk of spreading from breath. Bottom line: there is likely some risk of spreading beyond 5 days, but it's small enough that a blanket recommendation for everyone to isolate for a full 7-10 day doesn't make sense. It makes more sense to exercise caution, like masking, and avoid close contact with high risk people.
Agreed. If Covid, they should definitely have two negative tests two days apart. The five day guideline is misguided and encourages people to push themselves when still ill (slowing recovery and increasing risk of long Covid) and means they are risking spreading to others. Even if not covid, five days is usually not long enough to have recovered and not be contagious anymore.
This is a great reminder of the basics, and I will implement when I can situationally. I think the value of asymptomatic rapid antigen testing has dropped pretty far (maybe 30% sensitivity?) but adds another layer of Swiss cheese protection. Ventilation is the best.
What do you think of nasal sprays like Enovid and Iota-Carrageenan? I wrote a post about this for my audience, do a free trial or I'll comp you for free if you'd like to read in its entirety!
https://mccormickmd.substack.com/p/nasal-sprays-for-covid-prevention
Hi Ryan, Here's a post I wrote about Enovid for Those Nerdy Girls. Here's an excerpt from my post:
Enovid / VirX/ FabiSpray is a nitric oxide nasal spray that could be a promising addition to our COVID-fighting toolkit. Yet, it’s by no means a silver bullet, or a reason to forgo well-established precautions and treatments. Expect to use this nasal spray several times a day during high-risk exposures or during infection. These products are not yet approved in Canada or the US, but things may change next year when Phase 3 data become available.
https://thosenerdygirls.org/nasal-spray-covid-treatment/
What do you mean by asymptomatic rapid testing having 30% sensitivity? Does that mean rapid tests only test positive 30% of the time when someone is infected with Covid but is asymptomatic?
Here is another study out recently that I just read:
“They found that on PCR testing, median cycle threshold (Ct) values hit their lowest point -- which is consistent with peak viral load -- on the fourth day of symptoms.
Using Ct values to predict rapid antigen results, the researchers estimated a sensitivity of 30% to 60% on the first day of symptoms, rising to 80% to 93% on the fourth day of symptoms.
Early in the pandemic, they wrote, a single negative antigen test had "reasonable negative predictive value," with studies reporting 90% to 95% sensitivity in the first week of symptoms. Now, overall predicted sensitivity in the first week is about 60% to 80%, they said.”
https://www.medpagetoday.com/special-reports/exclusives/106901
Hi - 30% is a lowball estimate, but the Cochrane review on this puts the sensitivity of rapid tests in asymptomatic individuals who were found to have Covid either later or by PCR (pooled analysis of several studies) around 50%.
I'll quote an article in the AAFP journal about this: https://www.aafp.org/pubs/afp/issues/2023/0400/cochrane-poc-rapid-antigen-tests-for-diagnosis-of-covid-19.html
Average sensitivity was greater in those who had symptoms (73.0%; 95% CI, 69.3% to 76.4%; 109 evaluations; 50,574 samples; 11,662 confirmed SARSCoV-2 cases) vs. those without symptoms (54.7%; 95% CI, 47.7% to 61.6%; 50 evaluations; 40,956 samples; 2,641 confirmed SARS-CoV-2 cases)....
In patients who were asymptomatic at the time of testing, sensitivity was higher when epidemiologic exposure (i.e., contacts of patients with confirmed cases) to the SARSCoV-2 virus was suspected based on studies reporting specific criteria for testing or referral for testing in the absence of symptoms (64.3%; 95% CI, 54.6% to 73.0%; 16 evaluations; 7,677 samples; 703 cases). By contrast, when COVID-19 testing was reported to be widely available to any asymptomatic participant, sensitivity was lower (49.6%; 95% CI, 42.1% to 57.1%; 26 evaluations; 31,904 samples; 1,758 cases).
...
Sensitivity varied widely among brands. Average sensitivities by brand ranged from 34.3% to 91.3% in symptomatic participants (20 assays with eligible data) and from 28.6% to 77.8% in asymptomatic participants (12 assays).1
Wow I had no idea rapid tests were inaccurate that much of the time in asymptomatic cases. Thanks for all the info!
Thanks, Ryan. I recently wrote a post for Those Nerdy Girls on asymptomatic testing and wanted to build on the great info you have provided from Cochrane. I think it's really important to note that test timing and repeat testing are key (both for cases with and without symptoms). For example, the US Test at Home study reported that a single RAT worked best on Day 4 (Day 0 = first PCR positive). At this point, a single RAT caught 75% of asymptomatic cases. Performance is much lower if you test in the first couple days after exposure. This makes sense because levels of the virus typically peak around this time.
https://thosenerdygirls.org/antigen-tests-asymptomatic-covid/
I really appreciate your practical advice. My family recently decided we were ready to go on a vacation for ten days. We flew. We stayed in a hotel. We ate from a buffet. AND we wore high-quality masks whenever we were indoors around other people, even for a minute, and we always ate outside. We met several lovely families doing the same due to many different reasons, including peanut allergies. We changed our paths to avoid people who were coughing when we could. There were plenty of them to avoid at the amusement park and zoo! It was hard to go without eating a proper meal in the airport and plane for six hours, but we did it! (We practiced the "hold your breath as you insert a big bite of granola bar before putting your mask back on" maneuver.) The trip was wonderful, and no one got sick. (And no one gave us funny looks or said a thing about our "odd" behavior that we know of.)
This was such a helpful, reasonable & human-centric approach to the realities of today’s (& tomorrow’s) decision-making regarding infection prevention. The fact that it is no longer stressed or even suggested just makes compliance that much more
challenging.
And the selfishness such silence condones is heartbreaking.
I know no one in our social groups or in our extended family who think about doing any of these things anymore, if they even ever did. But as a family with an immune-compromised member, we still have to make these considerations all the time. My husband and I weigh benefits/risks for every social situation we consider. People are shocked when I tell them I can’t attend a gathering because it’s indoors and for a meal and no one will be wearing masks. They look at us like we’re crazy. It’s just so frustrating when we are the ones always asking the questions about the details of an event. No one else considers limiting exposure to infection anymore.
Thank you for sharing your mental gymnastics. We see you and your continued balancing act. Those Nerdy Girls think about infection risks and tradeoffs. A lot. There is so much room in between doing nothing to reduce risks and avoiding all social contact. We are hopeful more people can navigate "the middle" with facts and empathy.
5 days after infection is not enough time for many to clear the virus. 2 negative tests 48 hours apart would be much safer criteria before attending an event.
Hi there, I just wanted to chime into this discussion as a Nerdy Girl who has been covering the testing "beat". The author (Ashley) was not suggesting that you would be negative by Day 5. She was suggesting that you are likely to get your first positive test by Day 2-5 after exposure. This is because takes a few days after exposure for the virus to reach sufficient levels to light up the test. The official recommendation for FDA/CDC is to wait 5 days after exposure before testing, to give the best chances of having enough virus to detect - and to re-test if negative. It's a different discussion with regards to how long it takes to clear the virus once you're positive. It's common to remain positive for 7-10 days after your first positive test - or longer!
Then, I suggest clarifying that on the article. She wrote, “If you have an infection prior to the event , you should wait 5 days from the start of symptoms before mingling with others.”
Hi! I thought you referring to when she said to test 2-5 days after the event to see if you picked up COVID! With regards to when it's okay to mingle, it's not black and white. Current guidance from CDC is to isolate for 5 days if you have symptoms, as this is when the vast majority of transmission happens. It's unclear how contagious people are after that, and the answer varies from person to person. It's not zero, but the risk does drop dramatically. We used to think that rapid tests were a great indicator of contagiousness, but I think it's increasingly unclear of how well viral levels in the nose represent the risk of spreading from breath. Bottom line: there is likely some risk of spreading beyond 5 days, but it's small enough that a blanket recommendation for everyone to isolate for a full 7-10 day doesn't make sense. It makes more sense to exercise caution, like masking, and avoid close contact with high risk people.
Agreed. If Covid, they should definitely have two negative tests two days apart. The five day guideline is misguided and encourages people to push themselves when still ill (slowing recovery and increasing risk of long Covid) and means they are risking spreading to others. Even if not covid, five days is usually not long enough to have recovered and not be contagious anymore.