[music]

Brian Lehrer: Brian Lehrer on WYNC. With COVID-19 cases rising, more governments and private companies are requiring proof of vaccination or recent negative test results for their on-site workers and patrons. With summer travel at its height, more testing is advisable if not required for that. AFT President, Randi Weingarten said on yesterday's show that although she's fully vaccinated, she gets tested before doing public events in addition, but which tests, for whom, and when to get them?

For guidance, we're turning to Dr. Daniel Griffin, an infectious disease clinician and as a researcher at Columbia, and chief of the division of Infectious Disease at the ProHEALTH Medical Group, he helped design the testing regimes for camps, professional sports teams, film and television workers, schools and companies. He's also helped with the design of a calculator tool for groups to decide what testing program makes health and economic sense for them. We'll also get his take on the news that the Biden Administration plans to recommend a booster dose for most vaccinated Americans, not just those with weakened immune systems. Welcome back to WNYC, Dr. Griffin. Thanks for joining us today.

Dr. Daniel Griffin: Oh, thank you. Good morning, Brian. Good morning, everyone.

Brian Lehrer: Listeners, if you have questions about testing. When and which one? 646-435-7280, 646-435-7280 for Dr. Griffin or tweet @BrianLehrer. To review the basics. There are two main types of tests to see whether or not you have COVID-19, PCR and antigen. New York City is requiring proof of a negative PCR test, the nasal swab for people who because of age or health can't get vaccinated or want to attend this week's homecoming concerts, for example. I think that's the weekly test that they'll require come fall for unvaccinated teachers. What does a positive result on a PCR test actually tell us versus the quicker antigen test?

Dr. Daniel Griffin: Brian, I like the way you break that down because testing does not need to be complicated. This is something I think all of our listeners here can understand. The antigen tests are actually picking up the viral proteins. These are these simple, they almost look like pregnancy tests, we get results in just a few minutes. They are less sensitive overall, compared to the PCR tests. They're very good at correlating when a person is infectious. Now, the PCR tests have always been referred to as the gold standard, but they're the most sensitive of our tests.

These are actually looking for the genetic material and they do this amplification process. There can be just a few hundred, a few thousand copies of this genetic material, and those tests will pick it up. A lot of us talked about using both modalities, just because resulting delays are so critical. If you say you've got a test that can give you an answer in 15 minutes but it's only 80% sensitive, well, in 15 minutes you've gotten 80% of those people identified, you can then pick up the rest with these PCR tests. The big challenge there is I think a lot of people are aware, is the cost, $10 for the antigen test versus over $100 for the PCR and resulting delays.

As there's more demands for tests, you may find out 36 hours later that person has a positive test. Unfortunately, after maybe they've exposed a lot of their loved ones, friends, co-workers et cetera.

Brian Lehrer: The PCR test shorthand tells you if you had any bits of SARS-CoV-2 floating around when the swab was taken, while the antigen test tells you you're infectious right then, but one thing I've heard about the Delta variant is that it seems to replicate faster, leading to less time between when you're exposed and you become infectious. Does that have implications for testing lags with a PCR test?

Dr. Daniel Griffin: I think that has huge implications, Brian, and I'll lay this out for our listeners. It used to be, and we've run these massive testing programs now for over a year where a person would get exposed. Several days later they would just start to have a little bit of viral replication that we could pick up with our PCR test, pull them out before they infected other people, and it wouldn't really be until the next day that they were infectious. It usually was about zero to seven days, about seven days from exposure to being infectious. We could usually pick these people up day five or day six.

It does look like with the Delta variant, it's about four days from exposure to being infectious. It looks like you go from having just a little amount of that detectable virus to being infectious in just a matter of hours rather than that day. Our whole idea that we're going to pick up people early with PCR before they become infectious, we may be losing that advantage. We're tracking this closely. The antigen tests become more and more important to get that result right away before that person enters a workspace, a school, a place where they might infect others.

Brian Lehrer: That's so interesting because we've considered the PCR test casually the gold standard. It sounds like the antigen test is becoming even more relevant than the PCR standards for all these back to work or who gets to go to a concert kind of situations and things like that?

Dr. Daniel Griffin: A lot of times, a complementary approach and we'll do this in a lot of our urgent care centers, our offices throughout the New York State area at the ProHEALTH, where someone comes in, we'll do that antigen test right off, if it's negative but we're still worried, we'll complement it with the PCR. A lot of times that $10 antigen test upfront and then that more expensive PCR test at the end. When people come to the hospital, really a separate question. Were they sick over these last 7 to 10 days? Then the PCR is really the right test in that situation.

Brian Lehrer: For companies designing back to on-site work systems or for entertainment venues that are offering a negative test option, which kind of test and how often should it be required?

Dr. Daniel Griffin: This is exactly why we created this calculator, which we put up on our Parasites Without Borders website and it's free. Anyone can use this because these tests cost money and there's only limited resources. People have to ask, what are we trying to do or how we're going to approach this? If you think about someone going-- we'll use a bar or a restaurant. If they've had a PCR that's been negative within the last 24, 48 hours, that used to be very reassuring before the Delta variant because it usually took a certain amount of time before they would become infectious.

Now that negative test two days ago, unfortunately, does not predict the future, it doesn't predict what's happening now. An antigen test right before you walk in the door may end up being the right test for you, depending upon your level and the risk factors, the people entering the venue. You may want to look at both modalities. You might want to say, "Great, get that PCR." Before you walk in the door let's just do a final check with an antigen test.

Brian Lehrer: Caroline in Manhattan, You're on WNYC with Dr. Daniel Griffin. Hi, Caroline.

Caroline: Oh, I'm sorry, is it me?

Dr. Daniel Griffin: It is you?

Caroline: Oh, my niece just graduated mortuary school in Washington DC and is working in the funeral home. She says basically, the rapid test does nothing for the Delta virus. That it has to be thrown out and they have to find something new.

Dr. Daniel Griffin: Let me address that. I've definitely heard that and I'm going to challenge it and say I don't think that's true. We have ramped up the number of tests, and here in the New York area, the majority of our positive tests are Delta variant now. The antigen test, I will say at a vaccinated person who probably has a narrow window of infectiousness is really great at catching those people quickly. The FDA has reviewed all our current testing and the Delta variant does not change the power of these tests, the sensitivity, the specificity. I know there's a lot out there saying that, but I do not think the science supports that.

Brian Lehrer: Ken in Bay Ridge, you're on WNYC with Dr. Griffin. Hi, Ken.

Ken: Hi. I have a question for Dr. Griffin on just the variousness of the way that we're getting our PCR tests. I'm a freelancer and so sometimes I have people going deep into my nasal cavity. Sometimes they give it to you and just ask you to do five swabs around in a circle per nostril. Sometimes they do it for 15 seconds, sometimes they do it for 10 seconds. It seems like no one does a PCR test the same way. I was wondering if you could offer your opinion on, is there a proper way to get a PCR test?

Dr. Daniel Griffin: This is a great topic and hopefully this will be helpful. I don't want to criticize all the different providers with their various styles but I'll give a little bit of the history and why we are doing it the way we are doing it and really the science that how to do it the best way. When we first started doing these tests, people would do that beautiful test right where they would stick a Q-tip way too far into your nose. You feel like you were getting a brain biopsy, twirl around, maybe do that on the other side, send this off for our PCR testing early on.

One of the studies that we did actually out in the Everett clinic in Seattle, we really asked the question, do you really need to stick that Q-tip all the way in there? A blind procedure, sometimes triggering a migraine, bleeding, or can you just do a good swab of the front of the nose? What we found is it really had the same sensitivity. It's just a couple of cycles earlier on the PCR that it would come up. Really saying you don't need to do those deep swaps. That increased amount of sensitivity is really not worth the trauma. That really carries across. Our tests continue to be incredibly sensitive.

You will miss a few people with a tiny amount if you don't do that deep test, but I'm not sure you need to do that deep test except for rare circumstances.

Brian Lehrer: Have they stopped doing the brain scraper test more or less?

Dr. Daniel Griffin: I will say if you go to a proHEALTH facility, yes, but several other institutions maybe haven't kept up with the data. They continue to have that historic approach to getting a sample. I'll say at a hospitalized patient, maybe it's 14 days in, you're not sure what's going on. You're hoping there might be just a little bit of virus left, then you might want to go ahead and do that deeper swab.

No, in general, as a screening test, the amount of trauma and really the discouragement for people coming back in to get tested frequently you can just do the anterior naris swabs, that's just inside the nose. Some of the home tests are based upon that approach, and then you now have a test that you can do more frequently with more uptake, with less trauma.

Brian Lehrer: Neal in Park Slope, you're on WNYC with Dr. Griffin. Hi, Neal.

Neal: Hi. Hello Brian. Thank you, Dr. Griffin. A question actually, I'm asking on behalf, yes, on behalf of myself, but I think a very large number of listeners are probably fully vaccinated and seem to be reasonably healthy, not showing any signs of COVID, and yet just the other day you had Randi Weingarten on, talking about she's been fully vaccinated and she's getting tested regularly. Now, most of us are not in the middle of giant crowds indoors, maybe the way she is as the union organizer, but for those of us who like me are mainly at outdoor events where most of the people are vaccinated, is there any reason for someone fully vaccinated in reasonably good health to be vaccinated?

Walking around Brooklyn, I see all these places for testing. These are not New York City institutions, they're like trucks or vans, and they set up, and is there any value whatsoever to be tested once, any circumstances being fully vaccinated and not having any symptoms?

Brian Lehrer: Right. Great question.

Dr. Daniel Griffin: Yes, fantastic question. We have great listeners, or you have great, Brian, I'm going to call them my own. This is something that has been discussed quite a bit, and I'm going to try to put context here is people who have been fully vaccinated are at a much lower risk of becoming infected, but they can still get infected. We do know that when a vaccinated person gets infected, that they, although they have a lower chance can spread it to others. This becomes the question, boy, I've already gone the eight yards, I've gotten vaccinated, I've done a tremendous amount. Do I really need to keep having Q-tips put up my nose?

Let's say you're going to visit your parents, maybe they have health problems. Before you go visit them, this can be another layer of protection. I think that's the way it needs to be looked at. People who are vaccinated, have a low risk but can get infected. They have a lower risk but can spread it. If they are going to spread it, it tends to be a much narrower window. I don't think the data is suggesting that they are teaming with virus. It looks like a shorter window, but they can spread it. This becomes an extra layer of protection if you're going to be, for instance, indoors. If you're going to be around someone, a vulnerable population.

We might go visit my parents in the coming week, maybe they'll hear about it here first, in the Brian Lehrer show, but I might have my wife, myself, and my son get a rapid test the morning before we go. Just add that extra layer of protection, and now that the tests are becoming accessible over the counter, you can do them yourself, about $10 a test, then it becomes something that you might want to consider incorporating into some of your decisions.

Brian Lehrer: Dr. Griffin's parents, if you're listening, hello. Now he's obligated, you can guilt him into it. He has to follow through and make that visit. Lisa, in Chicago, you're on WNYC. Hi, Lisa.

Lisa: Hi. I'm calling just because I wanted to add to the comments about the efficacy of the tests. I have COVID right now, and I found out on last Saturday and Sunday, I was exposed, but I found out that Tuesday that I had been exposed. I got a rapid and a PCR on Tuesday, and that came back negative. Another, because my job wanted me to get another rapid and PCR on Wednesday, that came back negative. I just went ahead and took an at-home rapid throughout the day on Thursday, because I started to feel sick. They came back negative, and then I finally paid for a rapid PCR out of pocket on Friday, that I tested positive then.

I am concerned that perhaps rapid may not be catching me the Delta variant, as much, or maybe not as soon as something else might.

Brian Lehrer: Yes, Dr. Griffin, are you hearing a lot of stories like that, or is this an anomaly?

Dr. Daniel Griffin: No. No. This is all about timing. I was giving you that number before, it's about four days. As you're telling me the story, I was counting the days and what I was getting from your story is your exposure last weekend, so then about Thursday, Friday, you start getting symptomatic. Initially, you're going to start off with the RNA that's just going to be detectable by the PCR, probably Thursday or Friday is when you get that. If you did an antigen test now, it probably would be positive, it probably would have been positive later in the day on Thursday.

Yes, the PCRs we still think are going to turn positive a little sooner, but with the Delta variant, it's probably just a matter of hours sooner where we saw with all the other variants. Now you're also going to experience the tail end. The tail end is you will stop being infectious, 10 days is what New York State says for your period of isolation for the infected. Now, at the end of those 10 days, your antigen test will be negative, but your PCR may stay positive for weeks, for months. We have patients 100 days out with still a positive PCR, but we're not seeing those people transmit.

I think what you're describing, and I think this was well done, is the test can't predict the future. You get that negative test on Tuesday, yet exposure Saturday, you are not yet at a point where you are infectious. You're not yet at a point where you're going to be testing positive. By Friday, you reach that point. I think that's an important thing. Don't let that negative test reassure you. If you're in that incubation period, which is 10 to 14 days per the CDC and per the science, at any point in time, you can turn positive.

Brian Lehrer: I'm told that in Israel, they're now considering using Antigen Rapid tests when there's a positive case in a classroom in school, in order to not keep opening, and closing, and quarantining kids all year, as we're already starting to do in some school districts that have begun already in this country. Do you think that's a doable system?

Dr. Daniel Griffin: I really think it is. There was a recent study, I thought it was really excellent, where they really start off by commenting that this idea of quarantining after you've been exposed, very few people, I hate to say, are doing this. If you've driven on the highway, but there's a speed limit, and no one seems to acknowledge that, nor do they with quarantine. They've said, "Is there some way that we can approach this, that people will actually find acceptable and will continue to keep it safe?" They went ahead and looked at the idea of just doing antigen tests every day, which as I point out are very good at picking up people who are infectious, contagious.

That is a model that is much more acceptable to people, allows us to keep those kids in school, allows people to get into the workplace. When you look at the models, it does not look like you're going to end up with more people being infected than the current approach, where you are asking people to be out of school, be out of work, to be isolated.

Brian Lehrer: Let me take one more caller before we run out of time, who is going to connect the question of testing, but a different kind of test to the news today, about the likelihood that most vaccinated Americans will be authorized for third doses of their mRNA vaccines after eight months following the second dose. It's Pearl in Manhattan, you got to ask this question. Pearl, you're on WNYC. We got about 30 seconds for you.

Pearl: I've been in the Moderna trial, so I was vaccinated last January. I'm just wondering, how can I know how effective, how much protection I still have? I've actually placed a call asking about to the trial people if they're going to do the third--

Brian Lehrer: Great question. Does any antibody test give people a reliable answer to that question and should that be a guide at all in terms of who should actually get a third dose when they authorize that?

Dr. Daniel Griffin: Yes. This is really a tough question because there's a lot of momentum here for the third doses, but we don't have the science that we would like, we don't have a blood test that tells us this person needs it or not. The part of our immune system that probably protects us the most against severe disease is probably our T-cells, that's what the hospital, long COVID perhaps, some of these other things, the antibodies may correlate with just getting an infection that doesn't result in disease, but that data is still not clear. We do know that these third doses are associated with an elevated anybody level. That's all very exciting, but we don't know what that actually means.

Brian Lehrer: With that bit of ambiguity, we have to leave it with Dr. Daniel Griffin, who gave us so many specific answers on testing infectious disease clinician and researcher at Columbia, chief of the division of infectious diseases for proHEALTH, that Medical Group and president of Parasites Without Borders. You can catch his weekly clinical updates on the podcast This Week in Virology. Thank you, Dr. Griffin, you have great listeners.

Dr. Daniel Griffin: Thank you.

Copyright © 2021 New York Public Radio. All rights reserved. Visit our website terms of use at www.wnyc.org for further information.

New York Public Radio transcripts are created on a rush deadline, often by contractors. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of New York Public Radio’s programming is the audio record.