Can you tell me a bit about Covid rapid tests?

[chocolate-chip chooky]

Australia seems to have given up on fighting Covid.

Two-ish years of fierce lockdowns, restrictions, closed borders etc seem to have been ditched for this new mentality. And right when this Omicron beast is arriving.

*sigh*

So, I'm wondering if rapid tests will be a new necessity in my Covid-prevention protocol.

Can you tell me a bit about how and when you use them? 

I need to get a feel for if they really are helpful or if they just make us feel better. 

 

[Acadie]

What I understand and have seen epidemiologists discussing on Twitter is that they're great for checking if you are contagious that day. Not so great at diagnosing Covid, for which a PCR test is going to be much more accurate.

But a really important and underutilized tool for public health. Test the day of a gathering, not before, to get a decent sense of whether you're contagious that day. An hour before would probably give the most accurate result. Serial tests for several days in a row increase accuracy, not to PCR level but much closer. 

We've used them when visiting older relatives, when having houseguests, for several days in a row when notified dd15 was a close contact (she was fully vaccinated so didn't have to quarantine but did need test results to stay in school), with allergies/sniffle, and will use them for several days, along with masks at home, when dd19 flies home tomorrow after lots of exposure due to travel. 

[busymama7]

My understanding is that they are really only accurate if you have symptoms. We've used them to confirm it was a cold and not covid when we weren't sure. 

[Pam in CT]

It varies a lot by regional / community / social circle / family culture.

 

In NYC, both PCR and antigen tests are free and easily available and have been for some time. It's enabled a culture where a whole lot of people routinely test. Prior to vaccines, many employers required weekly negatives. Post vaccine, my (vaxxed) relatives there regularly test before dinner parties or extended family gatherings.  My (inexplicably) single nephew gets one before every date.  There is, naturally, an app.

In my town (~50 miles outside NYC), which has one of the highest vax rates within one of the highest vaxxed states, and in which testing is available but not quite as convenient and/or not free, depending how you do it, folks tend to test for a particular reason. I test before I see my (vaxxed) octogenarian relatives, for example; and asked all my Thanksgiving guests to test before we came together. Most of them were coming from NYC, so didn't bat an eye. My (vaxxed) mother, who lives in a 3rd state, had never tested at all before. She used an at-home rapid test, with me, and was pleased that it was NBD. 

My boarding school/university kids were tested 1-2/week before vaccination, and randomly since, as a condition of being on campus.

There were some supply chain hiccups on the at-home kits a couple months ago, but they're easy to get online these days.  They run around $8-12/test, usually sold in packs of 2 or 5.

 

[busymama7]

My understanding is that PCR is needed to catch asymptomatic or pre-symptomatic cases so personally would choose a PCR test before seeing a relative or going to an event (with isolation after test). But I realize that availability would be regional etc. 

[KSera]

2 minutes ago, busymama7 said:

My understanding is that they are really only accurate if you have symptoms. We've used them to confirm it was a cold and not covid when we weren't sure. 

This was the reason that initially I was uninterested in rapid tests, but understanding what they are useful for better now, they still have very helpful utility before gatherings. Without symptoms, they’re not very sensitive to tell you for sure if you have Covid or not, but they are quite good at telling if you are shedding contagious virus. So, you might get a negative rapid test even though you have Covid, but you probably are not contagious then. Conversely, you might get a positive PCR before or after the contagious period. That’s why the rapid tests are only valid for a short while though; someone who is infected can rapidly move from not contagious to contagious. We will all use them directly before  seeing family at Christmas. We did not see anyone else last Christmas. 

[Laura Corin]

We are encouraged to use them routinely before socialising.  It's compulsory to test before I visit my mum in her care home.

[KSera]

2 minutes ago, busymama7 said:

My understanding is that PCR is needed to catch asymptomatic or pre-symptomatic cases so personally would choose a PCR test before seeing a relative or going to an event (with isolation after test). But I realize that availability would be regional etc. 

To me, The gold standard would be a PCR a couple days ahead of time, to give it time to come back, and then a rapid test right before hand. A PCR needs to be done far enough ahead of time that it’s possible for someone to be negative when it was taken but then positive by the time of the gathering. That’s how omicron spread so much by people who had to take PCR tests within three days of their flights. They were negative when they took them, but positive by the time they flew. That would be the reason for the antigen rapid test right before hand to check for viral shedding right at that time. 

[wathe]

Rapid Antigen Tests (RATs) are less sensitive than PCR tests. 

Graphic below is from the Ontario COVID 19 Science Advisory Table Brief on Rapid Antigen Testing, (which is absolutely worth reading - lay summaryhere, full brief here..

Rapid tests are going to be positive when your viral load is high.  Including during the pre-symptomatic period.  Which is super useful as a screening test.  It's not adequately sensitive to use as a rule out test for diagnosis  - you need PCR for that.

ETA: RATs positive approx 1 day pre-symptomatic for wild-type, and postive up to 4 days pre-symptomatic for delta.   Who knows for Omicron, but if I had to guess, I would guess perhaps more like delta than wild-type in terms of RAT bring positive several days before symptom onset.

 

 

 

Edited December 15, 2021 by wathe

[wathe]

We will be RATing all attendees to our small family Christmas gathering.  Those who live here (we are hosting) will RAT the day of arrival, early enough to cancel if anyone is positve.  Guests will RAT upon arrival. 

I found a medical supply company from which to buy the RATs, as general public access in my province is very limited (and, of course, just today the province announce that it will be providing general public access to free RATs - at least I don't have to scramble to get them.  A $$ test in the hand is worth many free tests in the bush, at least that is what I'm telling myself.  My $$ RATs arrived today).

[mlktwins]

55 minutes ago, busymama7 said:

My understanding is that PCR is needed to catch asymptomatic or pre-symptomatic cases so personally would choose a PCR test before seeing a relative or going to an event (with isolation after test). But I realize that availability would be regional etc. 

I agree and we are going through some stuff now as one of my household is now considered a close contact.

If you are asymptomatic or pre-symptomatic, the the most accurate way to test is a PCR between day 5 and day 7 after exposure. The results will take a couple of days to get back.  If someone is out and about between getting a PCR and getting results, they could still end up a positive, but they wouldn't know because they got it after the PCR test was taken. 

[Bootsie]

11 minutes ago, mlktwins said:

I agree and we are going through some stuff now as one of my household is now considered a close contact.

If you are asymptomatic or pre-symptomatic, the the most accurate way to test is a PCR between day 5 and day 7 after exposure. The results will take a couple of days to get back.  If someone is out and about between getting a PCR and getting results, they could still end up a positive, but they wouldn't know because they got it after the PCR test was taken. 

Aren't there PCR tests now for which results are available within a couple of hours?  I don't know if there are an at-home tests that are PCR, though.

[Acadie]

15 minutes ago, mlktwins said:

If you are asymptomatic or pre-symptomatic, the the most accurate way to test is a PCR between day 5 and day 7 after exposure. The results will take a couple of days to get back.  If someone is out and about between getting a PCR and getting results, they could still end up a positive, but they wouldn't know because they got it after the PCR test was taken. 

We went through the same recently and were notified on day 3 after exposure. We opted for rapid tests on days 3 & 5, PCR on day 6, then another rapid test before PCR result came in. 

[chocolate-chip chooky]

48 minutes ago, wathe said:

We will be RATing all attendees to our small family Christmas gathering.  Those who live here (we are hosting) will RAT the day of arrival, early enough to cancel if anyone is positve.  Guests will RAT upon arrival. 

 

This is pretty much what I'm pondering for us for Christmas.

If Covid cases really spike here in the next week, then we'd postpone. And if anyone in our party had any symptoms whatsoever or had been at an alert venue, then we'd obviously postpone.

But if everyone is well and aren't known contacts, then maybe RATs are a reasonable measure for peace of mind.

Everyone in our party is double-vaxed, but only two will be boostered. Many will be at about 4 months post-second vax. Three people over 80.

I really value your input on this @wathe Thank you for chiming in.

[Pam in CT]

quick turnaround PCR tests

7 minutes ago, Bootsie said:

Aren't there PCR tests now for which results are available within a couple of hours?  I don't know if there are an at-home tests that are PCR, though.

Yes, in NYC the turnaround seems to average ~6 hours or so.  The last time my husband and I tested we had results in < 4.  But it varies a lot by region.  Here in CT the results are usually coming in the following day, except Sunday which spills over to Monday.

I am not aware of any take-home PCR tests, only the antigen.

 

[wathe]

4 minutes ago, chocolate-chip chooky said:

But if everyone is well and aren't known contacts, then maybe RATs are a reasonable measure for peace of mind.

 

This is our situation.

If anyone is symptomatic then we will cancel.

[wathe]

2 minutes ago, Pam in CT said:

quick turnaround PCR tests

Yes, in NYC the turnaround seems to average ~6 hours or so.  The last time my husband and I tested we had results in < 4.  But it varies a lot by region.  Here in CT the results are usually coming in the following day, except Sunday which spills over to Monday.

I am not aware of any take-home PCR tests, only the antigen.

 

As far as I am aware, all PCR diagnostic tests are run in a lab.  I don't think that there is such a thing as a point-of-care diagnostic PCR test.

Turn around time depends on proximity to the lab, and how quickly the lab gets the processing done.

Our TAT is about 24 hours.  Most of that time is spent waiting for transit to the lab, in transit, and waiting to be processed.  The actual processing time isn't very long.

[ScoutTN]

15 minutes ago, Bootsie said:

Aren't there PCR tests now for which results are available within a couple of hours?  I don't know if there are an at-home tests that are PCR, though.

Most PCR tests here come back the same day, if you test before mid to late afternoon.

[KSera]

5 minutes ago, Pam in CT said:

quick turnaround PCR tests

Yes, in NYC the turnaround seems to average ~6 hours or so.  The last time my husband and I tested we had results in < 4.  But it varies a lot by region.  Here in CT the results are usually coming in the following day, except Sunday which spills over to Monday.

 

Results that fast on a PCR would make such a big difference. Here, sometimes people get results in less than 24 hours, but next day seems more common, and sometimes 2-3 days. So, people usually test 3 days before whatever they need it for, to ensure it comes back in time. Which of course is not nearly as accurate as if they had been able to PCR the same day and get it back in time.

[Melissa Louise]

9 minutes ago, chocolate-chip chooky said:

This is pretty much what I'm pondering for us for Christmas.

If Covid cases really spike here in the next week, then we'd postpone. And if anyone in our party had any symptoms whatsoever or had been at an alert venue, then we'd obviously postpone.

But if everyone is well and aren't known contacts, then maybe RATs are a reasonable measure for peace of mind.

Everyone in our party is double-vaxed, but only two will be boostered. Many will be at about 4 months post-second vax. Three people over 80.

I really value your input on this @wathe Thank you for chiming in.

We are in a similar position. 

It's going to be crazy $ to rapid test everyone, though I know our two travellers plan on doing both PCR before flight then rapid test Xmas Day.

I'm considering getting ds rapid tested - he's going to be high exposure right up till Xmas Day. 

Not sure rest of family will test, but they are all either boostered or recent double vax w Pfizer. 

For myself, I'm going to pray it doesn't rain, or isn't 40+ degrees, and stay outside as much as possible, and mask indoors. If the weather is inclement, not sure what I will do. 

[wathe]

We can get high priority PCR tests back in less than an hour for select, very high priority hospital patients in hospitals.  But that means budding in line in the hospital lab.

[Melissa Louise]

What I would like to know is how do you actually use them? Like, I buy a box at the pharmacy, I open it - what do I see? What do I do? 

PCRs go really high up in the nose - are we meant to do that? 

[wathe]

3 minutes ago, Melissa Louise said:

What I would like to know is how do you actually use them? Like, I buy a box at the pharmacy, I open it - what do I see? What do I do? 

PCRs go really high up in the nose - are we meant to do that? 

Instructions.

ETA: can do either nasopharyngeal (aka brain tickler)or nasal (nostril)

Edited December 15, 2021 by wathe

[KSera]

1 minute ago, Melissa Louise said:

What I would like to know is how do you actually use them? Like, I buy a box at the pharmacy, I open it - what do I see? What do I do? 

PCRs go really high up in the nose - are we meant to do that? 

None of the home ones I've seen require a high swab. I can't imagine they would make home tests that way. The one that is most common in the states has a little card inside with a well to add 6 drops of a liquid reagent that is in the box. Then you open a packaged swab and swab the lower nostril for 15 seconds (and at least 5 times around) in each nostril. You then insert the swab in the card so it contacts the reagent and turn it three times to mix. Then you close the card and wait for the liquid to wick across a pregancy test type strip. Between 15-30 minutes, one line=negative and two=positive. There are other tests that are variations, and I don't know which type you have in Australia.

[KSera]

2 minutes ago, wathe said:

Instructions.

ETA: can do either nasopharyngeal (aka brain tickler)or nasal (nostril)

I do worry about the complicated-looking instructions. The first time I did a Binax, one of my first thoughts was that there's no way that everyone is reading the full instructions and doing it correctly. I see why home test results without a proctor aren't accepted for official things, even for something that accepts supervised rapid tests. It's not actually complicated, but the instructions look daunting.

[chocolate-chip chooky]

7 minutes ago, Melissa Louise said:

We are in a similar position. 

It's going to be crazy $ to rapid test everyone, though I know our two travellers plan on doing both PCR before flight then rapid test Xmas Day.

I'm considering getting ds rapid tested - he's going to be high exposure right up till Xmas Day. 

Not sure rest of family will test, but they are all either boostered or recent double vax w Pfizer. 

For myself, I'm going to pray it doesn't rain, or isn't 40+ degrees, and stay outside as much as possible, and mask indoors. If the weather is inclement, not sure what I will do. 

Our gathering is only 11 people, and I've just ordered a box of 20 of the V-chek as listed on here: https://www.tga.gov.au/covid-19-rapid-antigen-self-tests-are-approved-australia 

$13.50 per test.

I still don't know if we'll even gather for Christmas, but I do feel a bit better for having made the order. I feel like we might have options at least.

I'm lucky in that all the extended family will do whatever I say. This means I get what I want, but it also means that all the responsibility is on my shoulders.

[Carrie12345]

Our family mostly uses them for calculating isolation time, since it can take us a few days still to get a lab result. 

[chocolate-chip chooky]

9 minutes ago, Melissa Louise said:

What I would like to know is how do you actually use them? Like, I buy a box at the pharmacy, I open it - what do I see? What do I do? 

PCRs go really high up in the nose - are we meant to do that? 

The ones I just ordered are like lollipops. You pop it in your mouth and rub it around in there for about 90 seconds. Then you put the swab into a thingy, and then in 10 min you have a result.

It sounds simple enough, but I'll let you know once we've tried it.

 

[chocolate-chip chooky]

@Melissa Louise I ordered from here: https://salivacovidtest.com.au/ 

[chocolate-chip chooky]

Just now, chocolate-chip chooky said:

@Melissa Louise I ordered from here: https://salivacovidtest.com.au/ 

According to the govt document, this test is rated at the highest sensitivity. 

• Very high sensitivity - clinical sensitivity greater than 95% PPA

[KSera]

7 minutes ago, chocolate-chip chooky said:

The ones I just ordered are like lollipops. You pop it in your mouth and rub it around in there for about 90 seconds. Then you put the swab into a thingy, and then in 10 min you have a result.

Nice! I haven't found any home saliva based ones here. Would be a particularly nice option with little ones who get a bit ticklish about having their noses swabbed.

[Melissa Louise]

Thank you for the link. Will forward to a few people.

That is crazy $ though. And I just spent $$ on P2 masks for everyone. Yikes!  I might try to get a smaller pack of tests for ds. 

Glad you're keeping safe. 

[chocolate-chip chooky]

2 minutes ago, KSera said:

Nice! I haven't found any home saliva based ones here. Would be a particularly nice option with little ones who get a bit ticklish about having their noses swabbed.

Yes, I know! I was so pleased to see a saliva option that was listed as 'very high sensitivity' on our govt website.

Thank you for joining in the conversation @KSera I know that you're on top of all things Covid, so I appreciate your input.

[chocolate-chip chooky]

4 minutes ago, Melissa Louise said:

Thank you for the link. Will forward to a few people.

That is crazy $ though. And I just spent $$ on P2 masks for everyone. Yikes!  I might try to get a smaller pack of tests for ds. 

Glad you're keeping safe. 

I am very very very fortunate that I am in a position where I can afford that for our gathering. If I'm going to insist on everyone testing, then I'll pay for the tests.

That's a pack of 20 that I ordered, but there are other types of RATs that you can get in chemists, I think. You might want to check the list for their sensitivities though. They range from 'acceptable' to 'very high'. 

[Melissa Louise]

Just now, chocolate-chip chooky said:

I am very very very fortunate that I am in a position where I can afford that for our gathering. If I'm going to insist on everyone testing, then I'll pay for the tests.

That's a pack of 20 that I ordered, but there are other types of RATs that you can get in chemists, I think. You might want to check the list for their sensitivities though. They range from 'acceptable' to 'very high'. 

Thanks, I'll do that. 

[KSera]

I just read this on Twitter 😭:

Sure, it’s just an anecdote, but I’ve seen more than one of these now. Crud. Not sure what to do about Christmas gathering now. I can’t imagine how this is going to go when schools open back up in January.

[mlktwins]

1 hour ago, Bootsie said:

Aren't there PCR tests now for which results are available within a couple of hours?  I don't know if there are an at-home tests that are PCR, though.

I can only say that our state department of health is recommending a PCR done between day 5 and day 7 from last possible exposure.  Our peds office said we will have the results within 1-2 days.  I would hope if there was a better, quicker PCR test, we would be getting that test.

[ScoutTN]

1 hour ago, Melissa Louise said:

What I would like to know is how do you actually use them? Like, I buy a box at the pharmacy, I open it - what do I see? What do I do? 

PCRs go really high up in the nose - are we meant to do that? 

Not all PCRs do that! Ours have just been lower nasal swabs.

[Melissa Louise]

Just now, ScoutTN said:

Not all PCRs do that! Ours have just been lower nasal swabs.

Oh, mine have all been brain ticklers! So horrid! (But also so quick, thankfully).

[busymama7]

8 minutes ago, ScoutTN said:

Not all PCRs do that! Ours have just been lower nasal swabs.

Same. And we've done quite a few.  

[cintinative]

My husband had a PCR at CVS (about a month ago) and it took four days to get the results. The one we did for my son a month before that or more took about three days. If you get them done at the hospital, the turnaround is faster. I would definitely not do a PCR (here) before the holiday. By the time you get the results back you could have been exposed.  I would much rather do the rapid, and if that comes back positive, do the PCR to confirm.

[bookbard]

I am wondering whether to bow out for our family Christmas. I suggest LFT but no one was keen. If it's pouring rain it will suck anyway, no one has the room for all of us. 

[lauraw4321]

Any time any of us has any CV like symptoms, we take one. So far they have all been neg.  

[chocolate-chip chooky]

@wathe Can I ask your opinion on something? 

We have cancelled our extended-family gathering, but my daughter's boyfriend will be coming over for a couple of days. My daughter is high-risk. Having him here is important to them, and they are willing to take the risk.

He will rapid test before coming. Do you have any advice as to how often he should rapid test once he's here at our place? Every 12hr? Every 24hr? 

 

 

[wathe]

@chocolate-chip chooky

I don't really know.

My thoughts:

Rapid testing before a visit is useful, because if it's positive, then you can cancel the visit and avoid the exposure.

Rapid testing during a visit is less useful, I think, because a positive tells you that you have already been exposed - the horse is already out of the barn.  Then what do you do with that?  Obviously you'd all isolate to prevent future spread to others, but it doesn't protect your DD from the exposure that's already happened.  So I really don't know how useful that is.

[Miss Tick]

2 hours ago, chocolate-chip chooky said:

We have cancelled our extended-family gathering,

I know it is complicated, but I'm sorry to hear that.

[NewnameC]

On 12/15/2021 at 3:33 PM, busymama7 said:

My understanding is that they are really only accurate if you have symptoms. We've used them to confirm it was a cold and not covid when we weren't sure. 

My sister‘s family all had Covid last month. All were vaccinated. Only one had symptoms—a headache. All tested positive with at-home rapid test. 
 

My niece also had a follow up test done at the doctor’s office and it was positive too.

So, in my limited experience the tests worked for asymptomatic people. (I also know they weren’t false positives, because someone my sister spent a lot of time with the day before BIL tested positive also got it and had symptoms.)

[chocolate-chip chooky]

On 12/23/2021 at 11:25 AM, wathe said:

@chocolate-chip chooky

I don't really know.

My thoughts:

Rapid testing before a visit is useful, because if it's positive, then you can cancel the visit and avoid the exposure.

Rapid testing during a visit is less useful, I think, because a positive tells you that you have already been exposed - the horse is already out of the barn.  Then what do you do with that?  Obviously you'd all isolate to prevent future spread to others, but it doesn't protect your DD from the exposure that's already happened.  So I really don't know how useful that is.

Thanks for helping me brainstorm this.

We absolutely agree that if he has a positive rapid test while here, then we're all exposed anyway, to some extent.

But we're thinking that daily rapid tests could achieve two things for us: Firstly, minimising viral load, if he does turn contagious. Secondly, peace of mind at the start of each day, so that we can all just relax and enjoy.

We're navigating a whole new normal here that we've been lucky enough to have been spared so far in the pandemic.  I'm really a bit lost.

 

[lewelma]

My ds's girlfriend is flying in to meet my son at his 91 year old grandma's house. She will stay 6 days.  All 3 of them will be boosted (but my son only 4 days earlier). She is very careful and has a great mask, but does have to fly cross country. We have 6 RAT tests. We are thinking that she tests before she leaves the airport, and then every 24 hours for 6 days.  And if she gets symptoms or a positive test she gets out ASAP.  The only other alternative, is for them to go into a hotel for 6 days until flying on to MIT. Thoughts? 

[ktgrok]

On 12/15/2021 at 6:01 PM, chocolate-chip chooky said:

This is pretty much what I'm pondering for us for Christmas.

If Covid cases really spike here in the next week, then we'd postpone. And if anyone in our party had any symptoms whatsoever or had been at an alert venue, then we'd obviously postpone.

But if everyone is well and aren't known contacts, then maybe RATs are a reasonable measure for peace of mind.

Everyone in our party is double-vaxed, but only two will be boostered. Many will be at about 4 months post-second vax. Three people over 80.

I really value your input on this @wathe Thank you for chiming in.

The chair of the Department of Medicine at a California university advises rapid tests for those who are vaccinated but not boostered, day of the event. 

Wachter says he's also covering up indoors with small groups of friends and family unless everyone is vaccinated and boosted. If they're not boosted, he says, "I consider them to be somewhere between vaccinated and unvaccinated, and I act appropriately if I'm going to be around them." That means he either has everyone mask up, or he has everyone take a rapid test to make sure no one is infectious at that moment. "One or the other." This is especially important if anyone attending is high-risk.