FDA Virtual Townhall

Moderator: Kemba Ford

1-6-21/12:15 pm CT

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FDA Virtual Town Hall Series –

Immediately in Effect Guidance on 

Coronavirus (COVID-19) Diagnostic Tests

Moderator: Kemba Ford

January 6, 2021

12:15 pm CT

Coordinator: Welcome and thank you for standing by. Today’s call is being recorded. If 

you have any objections you may disconnect at this time. All participants are 

in a listen-only mode until the question-and-answer session of today’s agenda. 

To ask a question at that time you may press star 1 and clearly record your 

name for question introduction. I would now like to turn the call over to your 

host Kemba Ford, thank you.

Kemba Ford: Thank you. Hello. I am Kemba Ford of CRH’s Office of Communication and 

Education. I’d like to welcome you to the FDA’s 38th in a series of virtual 

townhall meetings to help answer technical questions about the development 

and validation of tests for SARS CoV-2 during this public health emergency. 

Today Timothy Stenzel, Director of the Office of In Vitro Diagnostics and 

Radiological Health and the Office of Product Evaluation and Quality and 

Toby Lowe, Associate Director of the Office of In Vitro Diagnostics and 

Radiological Health, both from CVRH will provide a brief update. Following 

opening remarks we will open the line for your questions related to the 
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development and validation of tests for SARS CoV-2. Please remember that 

during this townhall we are not able to respond to questions about specific 

submissions that might be under review. Thank you and I’ll now turn the call 

over to Tim.

Dr. Timothy Stenzel: Hello everyone and welcome again to this continuing dialogue. It’s a new 

year. I certainly hope that this is a much better year for us due to our 

combined efforts than the last year. So we look forward to assisting the 

development of new products that can play a key role in the pandemic. 

We were busy over the holidays. If you remained aware we had a number of 

authorizations that happened and that has carried into this week. One 

authorization that’s a little bit unique is we did authorize the first antigen 

dipstick assay. So this is a simple strip that goes down into a test tube. It’s 

authorized for point of care. There’s been a lot of interest in the, you know, 

very inexpensive tests. And this antigen test doesn’t even have a test cartridge 

around it. 

So hopefully this adds to our arsenal. That is the Quidel QuickVue SARS test 

and, you know, joins the Abbott BinaxNow as a very, very simple, noninstrumented antigen test. And it’s just one example of the many awesome 

products that have been developed during the pandemic to meet our needs. 

And it’s I think a little bit unique in that it can really drive down the cost of 

the results and because it’s a rapid antigen test it can be produced in high 

volumes as you might expect just like the Abbott BinaxNOW.

And there are great other antigen tests. I just know that there’s huge public 

interest in driving s down that’s why I highlight that one. We of course want 

to continue just to make clear what our priorities are. They’re focused on 

those things that can have the greatest public health impact. So home tests, 
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home collections, point of care tests and super high volume central lab tests. 

All, you know, primarily the diagnostic tests but obviously we look at 

serology tests as well.

So, you know, these are our priorities. And if an application comes in and it’s 

complete and picks one of these boxes, we will make it a priority to give you 

feedback as soon as possible and try to authorize these tests as soon as 

possible.

We do continue to ask that the submissions are complete. That they’re well 

written and clear so that our folks can rapidly assess the submission. We also 

need Why Missing data submitted in a common spreadsheet so that we can 

look at the data very quickly. We don’t have to ask for this because we will 

ask for this. And really it’s considered incomplete unless we have that Why 

Missing data which should have the results plus any demographics of the 

candidate test plus the comparative tests in enough detail. 

We also want to see your protocols for your clinical examination study -

important and a detailed one. It's important to know how you selected 

samples, how you collected samples, how you tested samples, how you did 

the comparator assay. These are all really important questions. And we really 

can’t make our assessment without them. So it only slows us down if we 

don’t have complete information about these things.

I did want to also talk about another hot topic and that is mutation. So we’re 

all aware now of the UK variant mutation and it’s a concern in the U.S. and 

we’ve seen a handful already confirmed. And then also the South African 

variant which has some overlapping mutations but also some clear differences 

between the South African variant and the UK variant. 
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Both of these variants appear to be of higher infectivity due to the viral 

mutation with enhanced binding to the receptor and that’s the theory at least. 

There’s some pretty good evidence for that. Some of them may also have 

increased amounts of virus and then also greater binding to the receptor

obviously can lead into a greater impact.

So it’s important to understand the variants that are circulating. We do have 

an interest in sequencing-based tests that can provide a whole genome 

sequence. Of course we’ve already authorized at least one such kit. That’s 

the Illumina Kit. It is authorized and has within it reagents to sequence the 

entire genome. And that’s been a great step forward that we authorized quite 

a long time ago before we really knew how important the mutations would be.

The other thing that the FDA has been doing is on a regular basis of course 

with all applicants especially for the molecular assays we’ve been asking them 

at least twice during the authorization process to check the known sequences 

of variants and explain any challenges with their primer and probe sets that we 

have with those variants that are in the database. 

In addition the FDA has bioinformatics capability. We have the list of all 

EUA authorized primers and probes for molecular assays. And we have been 

interrogating the sequence databases to see if there are any mutations that 

could impact test performance. We have done this for the UK variant. We 

have done this for the South African variant. And we have done this prior to 

these variants for any variant that’s seen in the database that was at 5% of the 

sequences in the database or above. 

In all cases we reach out to the test developers. We ask for their assessment 

of the impact of these mutations on the performance of the test. We do our 

own evaluation of what we anticipate might be a significant potential 
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performance alteration. And work with the developers to assess the potential 

impact. As soon as all that work has reached a point where we feel like it’s 

important to share any information with the community we will. And what I 

can talk about today of course is publicly known that the UK variant there’s at 

least one test out there that has been publicly mentioned that’s the 

Thermofisher Attack Path Assay that has S gene dropout. 

So with S gene dropout we have looked at a number of variants in the U.S. 

database and a number of sequences. And the majority to date do not have all 

of the UK variant mutations. What that means exactly we’re not sure yet. But 

only a subset right now in the U.S. have - of the S gene dropout by 

Thermofisher have that. We believe that around 5% of the Thermofisher 

positives have an S gene dropout. But again as I said we think the great 

majority of those to date have not carried the UK variant mutation. 

So for the time being at least sequence verification of S gene dropout samples 

is something that we would recommend. Hopefully you have access to 

sequencing. As I mentioned there is an EUA authorized sequencing assay 

from Illumina that can suit this purpose.

Also you can reach out to your state and local public health labs and they may 

or may not have a sequence capability. Some of them do and/or they can 

guide you in what is the best process to assess this. If you’re a public health 

lab the CDC has asked that those isolates, those samples be sent to the CDC 

for sequencing. And so follow the CDC procedures and, you know, I would 

refer the public health labs to the CDC for any further questions on that. 

Obviously there are assay design issues that could be impacted by mutations 

particularly if an assay is a single gene target assay. And there are a number 

of single gene target assays that we have authorized. So it goes without 
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saying that multi-gene assays are going to be less impacted by mutations as 

they continue to propagate in this pandemic. And will have an advantage over 

single gene target assays. Some technologies don’t lend themselves well to 

multi-gene targets. We understand that completely. There’s nothing wrong 

with the single gene assay. However there is a little bit more pressing need to 

understand, you know, how variants might impact performance with single 

gene assays.

With the Thermofisher assay it is a 3-gene target assay and with S gene target 

dropout you can still detect positives by the other two targets. So we don’t 

know as of now that there’s any significant decrease in test performance of the 

Thermofisher assay. And for the moment at least it’s a very helpful assay to 

identify potential S gene dropouts that could be the UK variant as we try to 

assess whether spread is continuing within the U.S. of the UK on variant.

Moving onto antigen tests. Obviously there are mutations in the targets for 

antigen tests as well. It’s a bit more difficult to assess the impact on antigen 

tests because we can’t just simply look up sequences and primers and probes 

and identify whether there could be an impact on antigen tests. So the CDC 

has graciously agreed at least for the UK variants which they are now 

culturing to test the EUA authorized antigen tests at the CDC for their ability 

to detect the UK variant. 

So we will be reaching out to all of the EUA authorized antigen tests and 

asking them to send their kits. I think we need to be looking at 75 to 100 

test’s worth to send to the CDC because they do multiple levels and multiple 

replicates even for just a single variant such as the UK variant. So stay tuned 

with your EUA authorized antigen test and we will be reaching out to you 

with more information shortly.
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And finally I did want not mention serology tests. Obviously they can be 

impacted as well. And we will need to await the availability of immune 

serum or plasma from certain variant patients in order to assess the impact on 

serology. We have put requests out already for such samples. Obviously and 

thankfully at the moment there aren’t that many in the U.S. of the UK variant 

and the South African variant. But if they do become more prevalent we 

expect to be able to access immune plasma or serum to assess performance in 

serology tests. 

And again antigen and serology tests are a little bit more difficult beasts to 

handle when it comes to assessing their performance with variants but we’ll 

do our best here given the limitations of biology and science.

I don’t believe I have any other preliminary remarks. So let’s go ahead and 

open this up to questions and we look forward to that, thank you. 

Coordinator: If you’d like to ask a question at this time you may press Star 1 and record 

your name clearly. Our first question will come from (Wendy Strongen) your 

line is now open.

(Wendy Strongen): I had a question about what the template says for point of care studies. And 

it says that in addition to studies with 30 positive and 30 negative samples 

there should be a study with 5 to 6 untrained users with 3 positive and 3 

negative samples showing that they can perform the test just following the test 

instructions. My understanding is that those three positive and negative 

samples could be contrived swab samples. Is that correct?

Dr. Timothy Stenzel: Toby do you know the answer to that about contrived? I know we 

probably prefer pressure frozen samples for that. 
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Toby Lowe: Yes I’d have to look at the template to be sure. 

(Wendy Strongen): Yes I don’t believe...

Dr. Timothy Stenzel: I would ask that you send that question into our template email address box 

and we’ll give you a fast turnaround on that... 

(Wendy Strongen): I actually did send it in...

Dr. Timothy Stenzel: ...as accessible as possible to get more and more point of care tests 

authorized. And...

(Wendy Strongen): I actually did send that in already and I got an email back saying that was 

beyond the scope of things that could be sent in for questions. But I will send 

it in again.

Dr. Timothy Stenzel: Ask for - ask that Dr. Stenzel and Toby Lowe get copies. At least send it 

in. I apologize. 

(Wendy Strongen): Okay thank you very much. 

Coordinator: Our next question will come from (Isha Varilee) your line is now open. (Isha) 

please check your mute button. Again please check your mute button. Okay 

our next question will come from (Christine Shun) your line is now open.

(Christine Shun): For reporting purposes what CT cutoff would be appropriate and would it 

correlate with infectivity?

Dr. Timothy Stenzel: Can you explain your question a little bit more? Are you developing a 

molecular assay or using a molecular assay as the comparator?
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(Christine Shun): Using a molecular assay as a comparator for a rapid antigen test.

Dr. Timothy Stenzel: Okay. So what we ask is that you use the EUA authorized comparator test 

as its developed and that you report all results to us in alignment. We are not 

using a CT cutoff or some sort of infectivity cutoff because in fact CTs vary 

widely. For rapid antigen tests we have seen CTs as high as 40, four zero, in 

the first five days of symptoms. And exactly why that happens, don’t know 

yet. But we very clearly see a healthy or an unhealthy number of high CT 

results in the first five to seven days of symptoms. And so we feel it’s 

important that when someone has symptoms that we know the true 

performance of the antigen test. 

Now we do recommend that direct antigen tests - that their inclusion and 

exclusion criteria for their clinical study appropriately. We don’t really expect 

the antigen tests are going to perform well after five to seven days depending 

on the test. Some tests do a little bit better than that. The bulk of tests have 

been authorized in the five to seven-day symptomatic period. And we want to 

understand symptomatic people who are confirmed positive to be SARS 

positive, you know, what is the detection rate of those people with the antigen 

test.

(Christine Shun): Okay. And for clinical validation as a screening test, what is the 

recommended minimum number of positive and negative PCR cases?

Dr. Timothy Stenzel: If you’re going for a screening claim -- an asymptomatic screening claim -

and if you’re doing it as your first and only study, then I believe you need 30 

positives. If you’re adding it there are a couple of different options for you 

whether you’re adding it to an already authorized test or you are doing it in 

line with seeking your first EUA authorization. We have a minimum I believe 
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depending on the pathway at 10 positive asymptomatic patients premarket or 

preauthorization. 

If you’re doing this with an antigen test I would recommend that you perform 

a study that will maximize our understanding of your true performance in the 

asymptomatic population that makes sense. So as I said antigen tests are at 

their peak performance in the first five to seven days of symptoms. Virus

peaks - virus levels and shedding peak in that - typically peak in that window. 

And it may be, you know, earlier on in that window than later on in that 

window. 

We really, you know, know that after a week of somebody shedding the virus 

that antigen test performance will fall. And, you know, whereas a molecular 

test may be very - a good molecular test may be, you know, quite positive 

after 14 days. But, you know, well beyond perhaps the days of 

symptomatology if someone would be having symptoms. 

So sort of the best study design that will give you the best chance for showing 

excellent performance with an antigen test will be to link up with one of the 

serial testing programs. There’s many on college campuses, maybe in 

workplaces, maybe in schools. And, you know, screening at a minimum say 

of every week with a molecular comparator that can be used for the 

comparator of record for your asymptomatic study.

And you can enrich, you know, so you can wait until somebody identifies 

positives with that screening program. You can contact the individuals and 

see if they’re willing to test with your test. And then we’ll also want you to 

throw in an equal number at least of negatives to keep everybody honest. So 

that’s probably the best way to enrich for asymptomatic at levels of virus level 
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that we expect to see the antigen tests perform well in. I’ll pause there in case 

you have any questions about that study design.

(Christine Shun): Thank you for all of that information. I will take that back.

Dr. Timothy Stenzel: Okay you’re welcome. There’ll be a transcript of this that will be posted as 

soon as possible usually by Monday following for those who are interested, 

thanks. 

Coordinator: And as a reminder if you’d like to ask a question please press Star 1 and 

record your name clearly. Our next question will come from (Corbin Vencut) 

your line is now open.

(Corbin Vencut): Good afternoon. Thank you for taking the call. I just wanted to I think Dr. 

Stenzel mentioned about the priority of different tests. Do you mind if you 

can just tell the priority once again? I missed when you were talking. 

Dr. Timothy Stenzel: Oh yes just briefly. Point of care tests, home tests, in-home collection are 

primarily focused on diagnostic tests. So those would be molecular and 

antigen tests. But we will also make serology tests in these categories a 

priority. And then high throughput central lab testing that can really help 

drive down turnaround times for test results. These are usually on automated 

platforms or automated systems and those are the priorities. 

(Corbin Vencut): Thank you. So as far as the serology now that vaccination is getting 

implemented do you - I mean what does your office and the FDA think about 

the serology test in vaccinated individuals with the infection? Do you have 

any thought and guidance that you can share with us?
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Dr. Timothy Stenzel: Well first of all vaccines are reviewed by a different center. They are 

reviewed by CBER - C-B-E-R. And I would refer any questions you might 

have to them as well. 

The data needed to show that serology can be predictive in any way would be 

important for us to be able to review for any submission related to vaccine. 

There is no prohibition in any of the serology tests that we’ve authorized for 

use by clinicians to try to assess them. But we do always urge caution because 

we have not authorized any serology tests for use with vaccines for any 

purpose either to determine whether a vaccine is needed or determine if a 

vaccine has taken effect and provides any sort of immunity. 

In fact we haven’t even authorized the serology tests around an immunity 

claim. We have authorized semi-quant serology tests and a neutralizing 

antibody serology test. Those perhaps could be more useful in assessing at 

least the question of immunity not necessarily that anybody can use them right 

now to declare immunity. That would be something that I think would be a 

bit dangerous right now.

(Corbin Vencut): My question is similar to what you were mentioning about the variants when 

you have - you were telling, you know, you are going to look at the serology 

test how in the variant how they are performing. My question is the people 

who got immunized in those people how the serology tests will perform and 

will it give a false-positive? I’m kind of asking in that context rather than 

looking at the immunity level.

Dr. Timothy Stenzel: Yes I mean I think your question is if somebody gets a vaccine can you tell 

if they’ve developed antibodies...

(Corbin Vencut): I’m not asking that.
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Dr. Timothy Stenzel: We have not authorized the test for that. To get authorized for that purpose 

to allow marketing would require, you know, a potentially significant study, 

you know, in conjunction with the vaccine study or trial. So we’re open to 

developers who want to pursue this. We would ask that you draft a clinical 

study plan and send it to us and we would assess its ability to answer the 

question and allow an authorization.

I do believe these are going to be very significantly large studies. And, you 

know, it’s a bit dangerous for the FDA to say oh you’ve developed antibodies 

and the vaccine and now this is what it means you know? And so developing 

antibodies to a vaccine is potentially very similar to developing antibodies to 

the actual SARS infection. So, you know, but if someone who wants to 

pursue, a developer wants to pursue specific claims we’re open to looking at 

the design. We would review this in conjunction of course with CBER. 

Coordinator: And our next question will come from (Teresa Hermietch) your line is now 

open.

(Teresa Hermietch): Yes thank you so much for taking my question. My question is regarding 

the use of controls. Does FDA have any recommendations regarding the use 

of endogenous or exogenous controls for using an antigen test?

Dr. Timothy Stenzel: An antigen test. What kind of exogenous control? 

(Teresa Hermietch): We are in the process of developing so I just need a general guidance. If 

there is a guidance document or recommendation as to how we should be 

looking at controls for antigen tests. 

Dr. Timothy Stenzel: You know I mean it’s obviously nice to have controls especially 

endogenous control that could assess the quality of the sample. But it’s not a 
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requirement for EUA authorization. We will assess test performance without 

such. The only requirement regarding such controls or the only 

recommendation for controls has been to date with unobserved home 

collection samples. Where we just have no idea if a patient has self-collected a 

sample well enough for performance in an assay that doesn’t have endogenous 

controls. 

We have updated authorizations for some developers after they had already 

launched with an endogenous control and assessed performance in their home 

test looking at literally thousands of datapoints and have been able to back off 

on the requirement for endogenous controls in some cases. But for right now 

for a new developer with a new home collection we would like to see that 

data. 

(Teresa Hermietch): Thank you. I have another question regarding the use of antigen tests for 

screening purposes because the current antigen test they have intended use 

claims for a certain number of days post onset of symptoms. If you are 

planning to develop an antigen test for screening purpose given the antigen 

test is normally most effective the first week or 10 days post onset, how does 

FDA look at the clinical trial and also samples that are being collected? Do 

they have to because this is for asymptomatic what would be FDA guidance in 

that regard?

Dr. Timothy Stenzel: Yes. One of the previous callers had that same question and I went into 

long detail on that. So I would recommend that you - I’m not going to repeat 

it here. I would recommend you look for our transcript that should come out 

on or about Monday next week of my remarks on this call. It does suggest an 

optimized study design that will give antigen tests the best possible situation 

to show excellent performance in asymptomatic patients. 
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(Teresa Hermietch): Thank you.

Coordinator: And as a reminder I’d like to remind each caller to ask one question 

throughout today’s Q&A. And if you’d like to ask questions you may press 

Star 1 and record your name clearly. Our next question will come from 

(Wendy Strongen) your line is now open.

(Wendy Strongen): Could you comment on what are acceptable enrichment strategies for an 

antigen - a rapid antigen test and specifically would screening everyone 

coming to a COVID testing center for the presence of symptoms to COVID be 

an acceptable enrichment strategy? 

Dr. Timothy Stenzel: This is people with symptoms or people without symptoms that you’re 

looking for?

(Wendy Strongen): No we’re looking - we want to get positives so people are presenting to a 

COVID testing center. Some of them have symptoms, some of them don’t 

have symptoms. So in order to try to enrich to get symptomatic positives not 

for an asymptomatic claim we want to screen for people who have had 

symptoms in the last eight days or symptoms that started no more than eight 

days ago. 

Dr. Timothy Stenzel: And is this for an antigen test or for a molecular test?

(Wendy Strongen): A rapid antigen test. 

Dr. Timothy Stenzel: Yes. Well we might be amenable to that. I would send in, you know, a 

pre-EUA requesting the input on that. I don’t think it’s a particularly good 

study design. I’m just being honest. I mean the positivity rates out there are 

sky high. And, you know, you don’t have to run a lot of tests in the clinics 
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that’s seeing patients with symptoms to get your minimum 30 positives. And 

yes you’ll have, you know, a number of negatives. 

But unfortunately the virus is running pretty hot out there right now. And that 

kind of enrichment I don’t believe is needed and there are some challenges. 

We have expressed flexibility for enrichment around asymptomatic testing 

just because to do this well for an antigen test I believe it should be a 

population that is serially tested as they’ll give the antigen test the best 

opportunity to show its excellent performance in the first five to seven days of 

shedding a virus. But for those that have symptoms the virus is just, you 

know, hot out there.

But if you really want to pursue that send in a request for a study review and a 

pre-EUA and we’ll look at it. I just don’t - I don’t know what our team is 

going to say and I wouldn’t recommend it. 

(Wendy Strongen): All right thank you. 

Coordinator: Our next question will come from (Isha Varilee) your line is now open. Again 

if you called in from the line of (Isha Varilee) your line is now open. If 

you’ve pressed Star 1 to ask a question your line is open. Well then as a 

reminder if you’d like to ask a question you may press Star 1 to ask that 

question. Again to ask a question that would be Star 1. One moment please 

to see if we gather additional questions. And I’m currently showing no 

additional questions at this time. Oh there is a last minute question. Would 

you all like to take that or would you like me to turn that call back over?

Dr. Timothy Stenzel: Oh no we’ll take that it, you know, we’ll give some period of time after we 

have a last question for someone else to dial in up until the closing time. We 

don’t want to close out the call so yes we’ll take it. 
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Coordinator: And I believe that question comes from (Homer Pia) your line is now open. 

(Homer Pia): Yes hello (Homer Pia). Just a quick question around the mutation UK. You 

mentioned that CDC has agreed to perform, you know, some testing there for 

existing EUA tests. And I wonder would that be also available for the 

developers that are in the process of their developing an antigen test?

Dr. Timothy Stenzel: So, you know, I think that there is the right timing to do that. It would 

probably be after the assays have locked down. There may eventually be live 

virus of the UK variant positive in BEI bank and/or irradiated or heme 

activated virus. There also are pseudo virus constructs you can make to assess 

on your own. But I think we don’t necessarily want to inundate the CDC in 

early stage of development. 

We’re hoping that none of the antigen tests are impacted but it is important. 

And we’ll get a good idea I think with the first tests we look at. Frequently 

it’s the N gene that’s targeted by antigen tests. And that probably is a bit 

more conserved in some respect than the spec protein, okay? 

But once you’ve locked it down and you’re going to come in with submission 

I would reach out and check the status of this situation because I think, you 

know, it’s probably going to be beneficial for us to, you know, at this moment 

I would say it would be beneficial for us to know what the reactivity is of a 

developed test that’s being evaluated through FDA for the UK variant. We 

each want to time that correctly in your development process.

(Homer Pia): Thank you very much.

Coordinator: And our next question will come from (Isha Varilee) your line is now open. 
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(Isha Varilee): Hi can you hear me? Hello.

Dr. Timothy Stenzel: Yes. 

(Isha Varilee): Okay. You said my name before. You just didn’t pronounce right. I didn’t 

realize it was me. Anyways I thank you for having these townhalls they’re 

really helpful. So we are developing a point of care, over the counter test that 

is meant for workspace, for work, for schools. It’s a breath test. We sent - we 

submitted a pre-EUA in July in the beginning of July. And we were 

appointed a reviewer. We just haven’t received any feedback on our 

questions. And, you know, it’s been quite a while now and we really want to 

continue performing our validation study. 

So is there any advice you could give on that? And just the end of that 

question is would this validation study that’s appropriate for the EUAs could 

be appropriate for submitting a - for receiving a 510(k) clearance? Thank you.

Dr. Timothy Stenzel: So yes hang on the line a little bit. So if you reached out in July I don’t 

know that we would have had prepared recommendations to share with 

developers. Did you get any information back when you reached out that we 

had prepared because I know we now have prepared at least a subset of 

recommendations for breath test developers?

(Isha Varilee): We have not received any recommendation for breath test developers. And

we have tried to be in contact, in touch with our reviewer. 

Dr. Timothy Stenzel: Okay. Well I apologize for that. Send an email back to the template email 

box and ask for Dr. Stenzel and Toby Lowe to be copied on the request and 

we’ll make sure that you get feedback relatively immediately with those 
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recommendations and I’ll look into why your pre-EUA has not been 

responded to.

(Isha Varilee): Thank you. Just to make it clear. Should I send the pre-EUA together to the 

template now?

Dr. Timothy Stenzel: Yes you can copy that. You can copy that again, you know, advise the...

((Crosstalk))

(Isha Varilee): After - and we rewrote it after you published the template in the end of July so 

I could put both versions there. 

Dr. Timothy Stenzel: Okay yes that would be great. Make sure that your reviewer has both 

versions. But you can again send an email to the template team mailbox. Put 

both versions on. I’ll make sure that you get the feedback that we can 

immediately give for those that are seeking to understand what our 

recommendations are about breath tests. And again I will look into the preEUA and either Toby or I will get back to you with an update on that. 

I think you asked another question and I lost it. Could you re-ask the other 

question you had related to that?

(Isha Varilee): If we get the green light to go ahead with our clinical validation study - study

design would that be applicable for a 510(k) clearance as well?

Dr. Timothy Stenzel: Oh yes. Yes, so, yes let me just talk about the transition a little bit from 

EUA to 510(k)s or De Novos if you’re the first one in. And this applies to 

anything SARS related. And even for, like, some categories, like, molecular 

they’ll be at the bare minimum. A single target SARS - a single virus assay, 
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Page 20

like, SARS only category. And then there will be a panel category. Those 

each would be separate De Novo submissions. 

Once a De Novo is authorized within one of the categories every follow on 

assay will be a 510(k) submission. For those developers who want to know 

about what is required for the - what is recommended for the conversion we 

are working on a guidance document that would be a draft at first. But it may 

not go into enough detail across the board for all EUA type products. 

And so I have asked our team to draft some information that we can share 

with developers. Primarily it’s going to be what is different about SARS from 

a standard say antigen in infectious disease, in a respiratory infectious antigen 

serology and/or molecular test. So our feedback is going to be focused on 

what’s different because we’re just swamped with work and submissions. 

And so we want to focus on the things that are truly different about SARS and 

our responses. 

And then for, you know, the more common, factors for any of these categories 

of tests, you know, we would urge you to look at our recent decision 

summaries for De Novos and 510(k)s including any special controls for all the 

sort of commonly asked questions about a respiratory virus test. But we’ll 

focus on the things that are different. 

The other thing is there is - I do not perceive a need to rush to converting 

EUA. We still have so many EUA applications to process. And we get so 

many new ones every week. It’s really, you know, an unprecedented volume 

and continued volume. And so our focus is really going to be primarily on 

getting the EUAs authorized. And, you know, until the emergency ends 

which I don’t perceive this happening anytime soon, EUA submissions are 

going to be allowed, EUA tests are going to be allowed. 
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And even if it were to end at some point we’re drafting guidance that will 

allow a very reasonable transition timepoint, a timeline so that there will not 

be something that we believe is unreasonable insofar as time goes to convert 

these. 

But I do understand that, you know, we are going to ask more for conversion. 

And it probably is wise for all developers to start thinking about those 

conversions. And it leads to collecting the samples now when SARS is 

prevalent to be able to do those conversion studies if that’s interesting and 

important to you to convert at the point where it’s important to convert. So 

hopefully that answers the question. 

(Isha Varilee): Thank you.

Coordinator: And our last question will come from (Alexis Sauerbudge) your line is now 

open.

(Alexis Sauerbudge): Hi thanks very much for taking my call. I had a question with regards to 

the CDC test and the current mutation. Do you have any indication or 

information that the CDC primers may be affected by any mutations that are 

circulating?

Dr. Timothy Stenzel: Yes I would, you know, to be formally correct in my answer I would need 

to check with the team. What I will say is that as soon as we have confirmed 

the potential impacts on a test whether it be molecular, antigen or serology, 

we will endeavor to make that information public as soon as possible. So 

certainly the primers and probes sequences for the CDC assay are published 

and people can look at, you know, mutations and see how they might affect 

those primers and probes. But I don’t have anything to announce at the 
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Page 22

moment about any test other than the test I mentioned before which was the 

TaqPath.

(Alexis Sauerbudge): Great, thank you very much. I appreciate it.

Coordinator: And that was our last question. I would like to turn the call back over to 

Kemba Ford, thank you. 

Kemba Ford: Thank you. This is Kemba Ford. We appreciate your participation and 

thoughtful questions during today’s townhall. Today’s presentation and 

transcript will be available on the CDRH Learn Webpage at 

www.fda.gov/training/cdrhlearn by next Friday, January 15. If you have 

additional questions about today’s virtual townhall, please email CDRH EUA 

templates at fda.hhs.gov. 

As we continue to hold these virtual townhalls we appreciate your feedback. 

Following conclusion of this virtual townhall please complete a short 13-

question survey about your FDA CDRH virtual townhall experience. This 

survey can be found now on www.fda.gov/cdrhwebinar. Again thank you for 

participating in today’s virtual townhall. We hope that you will join us next 

week on January 13. This concludes today’s virtual townhall. 

Coordinator: This concludes today’s conference. All participants may disconnect at this 

time. Thank you for your participation. 

END