CDRH Virtual Town Hall #102

Mpox and COVID-19 Test Development and Validation

March 22, 2023

Joseph Tartal: Welcome, everyone, to today's Virtual Town Hall number 102 for mpox and SARS-CoV-2 

test developers. It has been a little more than three years since this series began in March of 2020.

Today will be the last of these recurring town halls, and we will discuss and answer your questions about 

diagnostic tests in response to the mpox and COVID-19 public health emergencies.

I am Joe Tartal, Deputy Director within the Division of Industry and Consumer Education in CDRH's Office 

of Communication and Education, and I will be your moderator for today's virtual town hall. Our 

panelists for today's program are Dr. Timothy Stenzel, Director of the Office of In Vitro Diagnostics, 

which is also referred to as the Office of Health Technology number 7, or OHT7, in CDRH’s Office of 

Product Evaluation and Quality, or OPEQ; Toby Lowe, Associate Director for Regulatory Programs, also in 

OHT7; Dr. Kristian Roth, Deputy Director of the Division of Microbiology Devices in OHT7; and Dr. Noel 

Gerald, Branch Chief for Bacterial, Respiratory, and Medical Countermeasures in OHT7 as well.

For today's virtual town hall, we'll begin with opening remarks. Then we'll answer your previouslyemailed questions. And then we'll address your live questions. As a friendly reminder for those of you 

participating live in today's virtual town hall, please be sure you have joined us by the Zoom app , and 

not through a web browser, to avoid any technical issues.

The presentation and transcript for our last virtual town hall, which was held on February 15, 2023, have 

been posted to CDRH Learn. A screenshot has been provided on this slide where you can find those

materials within CDRH Learn. Please use this valuable resource. 

I'd now like to welcome Tim, Toby, and Kris, who will provide today's opening remarks on the town hall 

program in general, and mpox and COVID-19. Tim, the floor is yours. 

Timothy Stenzel: Thank you, Joe. Hello and welcome, everyone. We have reached another milestone.

Based on current public health trends, we have decided that today will be the last regular recurring 

virtual town hall on mpox and COVID-19 test development and validation. As we have discussed on 

previous town halls, we are encouraging stakeholders to move towards a traditional marketing 

submission. Developers are encouraged to submit a Q-Sub or a Pre-Sub to address questions they have 

for these conversions from EUA tests to fully authorize tests.

We will, in general, allow use of the EUA data to decrease the validation needed. And this can be worked 

out through the Q-Sub, Pre-Sub process. We can also provide, through this process, our standard 

validation recommendations for your device type upon request.

This full authorization pathway is also open to developers who did not have an EUA authorization but 

want to develop a test. While the 564 declaration for both COVID-19 and mpox IVDs remain in effect, 

564, again, is a section of the Food, Drug, and Cosmetic Act. We are focusing on only a very limited set 

of priorities for both COVID-19 and mpox EUA reviews at this time. The COVID-19 transition plan 

guidance, issued in draft in December of 2021, will be finalized soon and will include additional 

information on the transition back to normal operations. We will host a town hall/webinar on the final 

guidance for IVD developers following the final guidance release, so be on the lookout for that 

announcement.
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Over the last three years, we have hosted more than 100 virtual town halls and have really enjoyed 

having this time to connect with all of you, learn more about your development activities and pain 

points, and answer your questions. While we won't be holding these sessions regularly, we will still be 

available for questions. You can always reach out to us by email at COVID19Dx@fda.hhs.gov, or for 

mpox, the MPXDx@fda.hhs.gov. Additionally, we may schedule ad hoc webinars on special topics for 

IVDs in the future, as this format seems to be helpful to many developers and other stakeholders. 

I'll move into general updates for this call. FDA recommendations in general, that is things like 

recommendations made in the COVID and mpox templates, and the standards ways of evaluating both 

EUAs for emergency response and traditional marketing IVD submissions are just that, 

recommendations. They are not hard and fast requirements. Through the COVID response and into the 

mpox response, the FDA has displayed a high degree of flexibility to meet the needs to match the 

situation currently on the ground. This is very much our standard operating procedure. 

So if our recommendations present significant challenges, reach out to us via either a pre-EUA for 

emergency response submissions or Q-Subs for full submissions, and discuss it with us. Present the 

issue, the challenge that you face, and a suggested way to overcome it. And we will review it and let you 

know through those either of those formal processes. We will consider changes to our recommendation 

when it makes sense for a specific given situation. We have demonstrated that we have done this, and 

will continue to demonstrate it going forward. 

Next I'd like to give a brief mpox update, IVD update. We have had questions about screening tests for 

mpox. The FDA is open to such screening tests. And if interested, please submit a pre-EUA. There are 

various US government-sponsored studies that are looking at this and may help inform both the sample 

type and/or appropriateness of a specific screening method. For the moment, though, lesion-based 

testing remains the most reliable method of detecting mpox. With that, I will turn it over to Toby next 

for some COVID-19 updates.

Toby Lowe: Thanks, Tim. Hey, everyone. Thanks again for joining us this week and for this whole series.

So we're going to talk a little bit about the transition. As we've discussed previously on the town halls 

and mentioned in the last town hall, the administration has announced that the public health 

emergency under 319 will expire on May 11 and will not be renewed. We've also discussed on previous 

town halls and in our FAQs on our website that the 319 and the 564 declarations are independent, and 

the 319 public health emergency expiration does not impact the 564 declaration, which is what gives us 

the authority to issue emergency use authorizations.

The COVID-19 EUA declaration under Section 564 of the FD&C Act will continue until the Secretary of 

HHS terminates it. And as is discussed in the draft transition plan guidance, we do expect 180 days 

notice before that 564 EUA declaration is terminated. We don't plan to take any action that would leave 

Americans without the tests that they need, and we recognize the need for manufacturers of tests that 

were issued EUAs to have an appropriate period of transition time to move to normal operations when 

the declaration under 564 is no longer in effect.

The draft transition plan guidance discusses that FDA intends to implement policies for continued 

distribution of tests previously issued an EUA while the manufacturer's traditional marketing submission 

is under review. And the final details for that will be described in the final transition plan guidance when 
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issued. And you may have seen on the OMB website that OMB has completed their review of the final 

transition plan guidances, so we do expect them to publish very soon. So keep an eye out for that. And 

as always, if you have specific questions about how to manage your current plans for your COVID-19 

test, you can always send an email to COVID19Dx@fda.hhs.gov or submit a pre-submission, as Tim was 

discussing, if you're considering submitting a De Novo or a 510(k). And now I can hand it over to Kris to 

give a couple other COVID-19 updates.

Kristian Roth: OK, great. Thank you, Toby. I just want to talk about comparator methods a little bit. So 

we have received several questions regarding appropriate COVID-19 comparator methods to support a 

De Novo or 510(k) premarket submission. And as we have discussed in previous town halls, we have 

some expectations that I'd like to highlight today.

The top choice for comparator methods for COVID-19 is an FDA-cleared RT-PCR test. As there are a 

variety of factors to consider for alternate comparator methods, we recommend that you submit a QSub or Pre-Sub, and we will provide additional information on appropriate comparators for your 

particular situation. To support a multi-analyte respiratory panel, we recommend that the comparative 

method for flu be a highly-sensitive, FDA-cleared, RT-PCR test, and typically we recommend that this is 

cleared within the past five years. However, we may consider a comparator that has been cleared 

previous to that time frame if you can demonstrate that the test performance is expected to remain 

unchanged with currently circulating flu strains; for example, providing an in silico analysis of the 

primers and probes, including contemporary strains.

Again, a Q-Sub will be beneficial in assuring that you use an appropriate comparator, and really just 

want to highlight that this is an issue that we are glad to discuss with you all, and it really is an important 

decision to make sure that your clinical trial or your clinical study really is designed appropriately. We 

similarly recommend using a high-sensitivity FDA cleared test, cleared within the past 5 to 10 years for 

other analytes in your respiratory panel. And again, bring us a Q-Sub and make these proposals to us in 

writing, and we can reply to you very quickly.

For questions related to specific submissions, including regarding special potential comparators-- sorry, 

excuse me, specific potential comparators and study designs, we recommend that you submit a Pre-Sub, 

also known as a Q-Sub, with information about your device, validation plans, and specific questions so 

that we can provide appropriate feedback and answers to your questions after considering your testspecific issues.

Next, I'd like to cover a couple of topics regarding flu B, influenza B. We have received several questions 

regarding flu B validation due to the low prevalence of flu B in the US. We recognize the need for 

additional tests for influenza, particularly over-the-counter tests and point-of-care tests, including 

respiratory panels with COVID-19. We will continue to tailor our validation recommendations to best 

serve public health needs. We have provided recommendations in our EUA templates, pre-EUA, and PreSubmission responses, and it is important to note that these are recommendations provided at a single 

point in time based on the available information at that time. They are not requirements, as Tim has 

mentioned, and we are open to alternate approaches to demonstrate performance of your test.

We encourage discussion of flu test validation as part of a Pre-Submission and with your lead reviewer, 

since this is an evolving issue. The recently-issued EUA for the OTC Lucira COVID-19 and flu home test 

included data from 94 subjects determined positive for influenza A by the comparator method and 0 
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subjects positive for flu B from the prospectively collected clinical samples. Banked patient samples 

collected in transfer media were used to establish test performance with flu B due to the low prevalence 

in the clinical study population and across the US, as reported by CDC.

As part of the conditions for authorization, the clinical performance of this test must be further 

evaluated in an FDA agreed-upon clinical study. The goal of such a study will be to establish performance 

for flu B in a clinical study with prospective samples. Due to the low levels of flu B in the past few 

seasons, we are adjusting our general recommendations for developers to target at least 30 influenza-Bpositive subjects in a prospective clinical study to support CLIA waiver or over-the-counter IVD 

indications. This differs from feedback developers may have previously received, such as in QSubmissions. 

These previous recommendations for testing included a target of 120 subjects positive by the 

comparator method for flu B to support CLIA waiver and OTC IVD indications. Again, we encourage 

developers to continue engaging with us on this topic. And with that, I will turn it back to Joe. Thank 

you.

Joseph Tartal: Thank you, everyone, for those opening remarks. We'll now answer your previouslyemailed questions about mpox and COVID-19 test development and validation. Please note, we do 

receive some emailed questions that are too detailed or test case-specific that we will not address 

during today's town hall. For those questions, we will try to send a response in writing within a few days. 

If you have submitted a question and do not hear it addressed today, please look for a written response.

If you do not receive a written response in a few days, please feel free to reach back out to us at 

MPXDx@fda.hhs.gov email box or to COVID19Dx@fda.hhs.gov mailbox for an update.

Also, we have received some specific questions as a follow-up to FDA feedback from the pre-emergencyuse authorization or pre-submission requests that we will not address during today's virtual town hall.

For these questions, we encourage you to contact your assigned lead reviewer to discuss or submit a 

supplemental request. So with that, let's talk about these questions.

So first, we have received no previously-emailed questions about mpox test development that we will 

address today. So we will move on directly to the COVID questions. So the first question, I will direct to 

you, Toby, which is, FDA recently granted a De Novo for Quidel's Sofia 2 test antigen for use in point-ofcare setting. Can an over-the-counter COVID-19 antigen test be submitted through the 510(k) pathway 

now using the Quidel's Sofia 2 test as the predicate device?

Toby Lowe: Thanks, Joe. No, the Quidel Sofia 2 test is cleared only for point-of-care use, not over-thecounter. And the regulation and special controls were drafted for point-of-care use. While we have not 

yet granted full marketing authorization for an at-home over-the-counter COVID-19 antigen test, we are 

interested in doing so, and the first such test would need to be granted through the De Novo pathway.

Joseph Tartal: OK, thank you for that response. We'll move on to our next question. We are developing 

an at-home SARS-CoV-2 test. The sealed cartridge will contain guanidine hydrochloride. Is this 

acceptable for an at-home test?
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Toby Lowe: Hazardous or irritating materials, such as guanidinium salts, should not be used for at-home 

devices unless the device has specific safety features to mitigate the risk of patient exposure. That might 

be, for example, releasing the preservative only when the container's lid is closed. We recommend that 

you provide the FDA with detailed design information, including images and a list of all reagents and 

concentrations, for an assessment of the toxicology profile of the components of your assay. We also 

recommend that your proposed assay labeling inform users of the risks associated with the use of your 

device as well as any recommendations for personal protective equipment. We recommend that you 

specify the volumes and concentrations of each reagent included in your test kit, and FDA will conduct 

an independent risk assessment to determine if the proposed mitigations are appropriate. 

Joseph Tartal: Thank you for that answer. We'll move on to our next question. At the current time, code 

QMN, COVID-19 multi-analyte antigen device in the FDA product classification database states 

emergency use authorization for regulation and classification. Will this be updated on the basis that the 

new COVID-19 test manufacturers are now encouraged not to use the emergency use authorization 

route?

Toby Lowe: The product codes that are existing will not be changed. They will remain as EUA product 

codes, and product codes will be added as new premarket submissions are granted or FDA cleared. You 

can also see on the molecular EUA web page and the antigen EUA web page, there's a blue box above 

the table of EUA tests, and that blue box points to the De Novo and 510(k) databases and lists the 

procodes for the tests that have received authorization through the traditional premarket authorization 

pathways, De Novo and 510(k).

Joseph Tartal: OK, good information to know. Onto our next question. There have been several EUAauthorized SARS-CoV-2 molecular tests that amplify and detect a single highly-conserved region of the 

SARS-CoV-2 genome. Can the FDA comment on the current thinking regarding single-target COVID tests 

for emergency use authorization now that there is a large database of genomic information available for 

manufacturers to utilize in the design of IVD tests? Would it be acceptable to use this approach for 

future premarket submissions?

Toby Lowe: As the COVID pandemic has progressed, we've observed changes in EUA test performance 

as new variants emerge. We have a good deal of information on our website about that. And there is a 

risk to public health if test performance changes as new variants harboring mutations in regions 

targeted by a molecular test emerge.

In general, tests that detect multiple SARS-CoV-2 targets have a lower probability of being impacted by 

mutations when compared with tests capable of detecting only one target region. It's likely appropriate 

that users of single-target tests be made aware of this risk through additional mitigations. So we would 

likely require additional labeling mitigations, so information in the product labeling about the risk of 

impact by mutations. And multiple target tests likely would not need these additional labeling 

mitigations.

Joseph Tartal: OK, thank you, Toby. Thank you for that response and your previous responses. This 

wraps up the previously-emailed questions for both mpox and COVID-19 test development. We'll now 

move on to the live question portion of the town hall.
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To ask a live question, please select the Raise Hand icon at the bottom of your Zoom screen. When 

you're called on, please follow the prompt in Zoom and select the blue button to unmute your line. Then 

identify yourself and ask your question. Please remember to limit yourself to asking one question only. If 

you have additional questions, you may raise your hand again to get back into the queue, and I'll call on 

you as time permits.

Our first live question is from Kal Mansoor. I'm unmuting your line. Please unmute yourself and ask your 

question. 

Kal Mansoor: Hi, Thanks for taking my question. My question is about flu B. So as prevalence has been 

low, so enrichment won't help, and if a sponsor does not have any retrospective samples to 

demonstrate flu B performance, what recommendations do you have?

Timothy Stenzel: So this is Tim. So first of all, the flu season is picking up in the Southern hemisphere.

And very frequently, flu B is more prevalent in the Southern hemisphere. So that is one pathway to 

collect flu B samples.

If we're talking about an EUA-- so that would be an EUA that's combined with COVID-- we will be 

relatively flexible about how we do this by alternate means. But we do need to understand flu 

performance in some way. An alternate approach is to potentially turn off the flu B signal in some way. If 

it's an antigen test, it can be masked with a change to the cover. Or if it's a molecular test, sometimes 

that can be done by electronic means, if it's an electronic readout. So come in with a proposal about 

how we can-- how you can validate this for discussion. I want to pause in case Kris has anything else to 

add. 

Kristian Roth: No, I don't. Thank you. 

Joseph Tartal: OK. Thank you for that question. Our next question is from Mary. Mary, I'm unmuting 

your line. Please unmute yourself and ask your question. 

Mary V: Thank you. My name is Mary, and this is regarding COVID. It's my understanding that it's 

acceptable to consistently collect the comparator method test swab sample prior to the candidate test 

swab sample in clinical studies for an at-home antigen test. So my question is, if the standard of care at 

the clinical site where clinical trials are taking place is to first test with an FDA EUA at-home antigen test 

as their standard of care, then a comparator method test swab is collected, then the candidate test's lab 

sample is collected, I just want to confirm that this order is acceptable. That's my question.

Timothy Stenzel: Yes. You do need to follow standard of care procedures per IRB recommendations, 

when appropriate. That can be a molecular rather than, necessarily, an antigen test. But obviously, it 

takes longer to get that molecular result back than an on-site antigen test. 

You can pause between collections, particularly between the molecular comparator collection and the 

candidate test collection, to allow what we call a washout period. Or we've seen in developers, sponsors 

of studies wait 15 minutes in between collections, and to date I'm not aware of any challenges that put 

any of the comparisons at a disadvantage. And you can also address this, if you wish, through, if it's an 

EUA submission, through the pre-EUA process or a Q-Sub if it's for a full authorization process. I'll pause 

here in case Kris has anything else to add.
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Kristian Roth: I guess the only thing that I would add is, at the beginning, or earlier in the pandemic, we 

were concerned with users being taught how to collect a nasal swab by that health care provider prior 

to self-collecting. And so I think now that we have half-- excuse me-- a billion tests distributed and more 

on the way, I think that concern is a little bit less. So as Tim mentioned, come in with a Pre-Sub and let 

us know how you plan to collect those samples. But I think that information has influenced our study 

recommendations.

Timothy Stenzel: So traditionally, we've been concerned about bias introduced from a health care 

professional collecting the sample prior to a self test. And now for home respiratory testing, at least, it's 

hard to imagine that there's any person left in the United States who can perform the testing on 

themselves or on somebody else, hasn't done a home test yet. So that pool of unbiased candidate test 

subjects is not available any longer, and I think people are pretty well-trained on collection and running 

a test. And so we're then, at this point, focused on the actual performance of the test. Thank you.

Mary V: Thank you. 

Joseph Tartal: Thank you for your question, Mary. Our next person up is Ray. Ray, I'm unmuting your 

line. Please unmute yourself and ask your question.

Ray Bandziulis: Hello, this is Ray Bandziulis from LGC Bio Search Technologies. My question is whether 

FDA plans to issue any specific guidance directed towards clinical laboratories who would wish to pursue 

a 510(k) or a path to clearance for their own institution. And I'm thinking this would be triggered in 

circumstances where the manufacturer of a SARS-CoV-2 test is not pursuing clearance themselves, but a 

key customer, key clinical laboratory may wish to continue using that test. Thank you.

Timothy Stenzel: The FDA has always welcomed lab-developed tests and labs to participate in FDA 

submissions, and we routinely have been authorizing such tests, even outside of an emergency 

response. Your specific situation has some inherent challenges, because I take it that it would still be a 

manufactured test. But you're not the manufacturer, unless you take on the manufacturing role for your 

own situation. 

So this is, I think, a perfect example of submitting your plans. And you can do that briefly, and if it's not 

enough detail, we can ask more questions. You can ask your questions and then submit that as a PreSubmission or a Q-Submission, and there's no charge for that submission. There is a guidance out there.

If you just submit “google FDA Q-Submission process,” it'll explain in detail how you do that and how 

you make that submission. 

It's just a formal way of the FDA receiving a submission electronically and logging it in and opening a file 

so that we have a record of our responses to you. We endeavor to hold ourselves to the words that we 

provide in that response to you, to your questions, for when you come back in. So it's all a matter of 

formal record that we can refer to, and you'll have a formal response that you can refer to as well. 

Ray Bandziulis: So just for clarification, that would mean being able to present a Pre-Submission that 

does reflect a unique situation where the clinical laboratory is the sponsor or the manufacturer, and 

somehow the manufacturer is the supplier? Is that a valid—
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Timothy Stenzel: Yeah, that's a very unique situation. And I think it's worthy of discussion with the FDA 

to find a way that we can do that.

Ray Bandziulis: Great. Thank you very much. 

Joseph Tartal: Thank you, Ray. Our next question is coming from Deb. Deb, I'm unmuting you. Unmute 

yourself and please ask your question. 

Debs Payne: Hey, Deb, last name Payne and the Promega Clinical Laboratory. We had notified the FDA, 

and we're in the EUA review process, but I'm not seeing that the Promega Clinical Lab is listed in the lab 

notification list on the FDA website. I sent several emails to the webinars and the EUA reviewer, and 

several other people, trying to get an idea of, who do I need a contact to see the PCL get listed in the lab 

notification list?

Timothy Stenzel: Yeah. Hey, Deb. So go ahead and send an email to the COVID email box, and ask this 

be submitted to Kris, Toby, and Tim.

Debs Payne: Yeah. I had sent it to Toby, just to follow up, because I seem to just not have the right 

email. So it's the COVID-19--

Timothy Stenzel: Dx, yeah, at fda.hhs.gov. 

Toby Lowe: Hi, Deb. I see your email from a few days ago. We'll take a look and get back to you. 

Debs Payne: OK. I just want to make sure that there's not any confusion. Thank you. 

Timothy Stenzel: And Toby may be able to expand why or why not something, in general, may not be 

posted. I think some of our processes have changed over time. 

Debs Payne: Yeah. I'm not sure if my reviewer is still assigned to me. But that's maybe a different topic, 

because I'm not getting a response from her either. 

Timothy Stenzel: OK, well, Toby's on top of it. Go ahead, Toby.

Toby Lowe: Yeah, we can look at that. And there is a difference between having submitted an EUA 

request and having notified, and so we can look into whether that's part of the issue. An applicant 

doesn't get listed on the notification list based on an EUA request being submitted. It's only if a 

notification was submitted earlier in the emergency, when we were accepting notifications through the 

previous policy.

Debs Payne: OK. So appreciate your work. I'm going to miss hearing your voices. Talk to you later. 

Toby Lowe: Thank you. Bye. 

Joseph Tartal: OK, thank you, Debs. Our next call is from Eileen. Eileen, I'm unmuting your line. Please 

unmute yourself.
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Eileen McCafferty: Hi, this is Eileen McCafferty, and thank you for taking the time to answer our 

questions today. I had a question requesting clarification to a FDA draft transition guidance, specifically 

on the discontinuation of distribution of IVDs after the EUA termination date. The FDA has stated they 

don't intend to request a market removal, but does the FDA intend to require the authorized 

distributors list under the EUAs to also stop distribution of product already in their control and out of 

the manufacturer's control?

Timothy Stenzel: OK, Toby is going to take this. But Eileen, you broke up for me. I'm not sure if you 

broke up for Toby.

Toby Lowe: Yeah, a little bit, but I think I understand the gist of your question. And the main answer 

really is to keep an eye out for the final guidances. We do expect them to post very soon based on the 

public notice that OMB has completed their review. So keep an eye out for those, and I think that they 

will provide more of the clarity that you're looking for. And then if you still have questions after the final 

guidances are posted, please send those in, and also keep an eye out for the webinars that will be 

focused specifically on those final guidances. 

Eileen McCafferty: OK, thank you. 

Joseph Tartal: Thank you. Our next question is from Alexandra. Alexandra, I'm unmuting your line. 

Please unmute yourself and ask your question. 

Alexandra Hubenko: Hi, this is Alex Hubenko I'm from the Radx-rad DCC at UC San Diego. My question is 

regarding the EUA templates. I've been working with teams on pre-EUA and EUA submissions, and there 

are still molecular and antigen templates posted on the COVID-19 EUA page. And I know that you've 

done one EUA for the InspectIR breath test, and I'm wondering if there will be a breath test EUApublished template.

Timothy Stenzel: No, there will not be a breath test template published. We're just not seeing a ton of 

those to justify the process that we have to go to clear a template and post it. But you can send a preEUA in requesting our standard recommendations for a breath test. That will go to the breath test team, 

and they will respond with their current recommendations for breath test validations. 

Alexandra Hubenko: OK, great. Thanks. 

Joseph Tartal: Our next question is from Stacey. Stacey, I'm unmuting your line. Please unmute yourself 

and ask your question. 

Stacey Moltchanoff: Hi, this is Stacey Moltchanoff from Thermo Fisher Scientific. I know that in the 

opening remarks, it was mentioned that there would be a certain amount of notice before the end of 

the declaration for either COVID or mpox. Is there any plans at this time for those EUAs to go away? And 

if so, how would that be communicated? 

Timothy Stenzel: Toby, do you want to handle this one again? 

Toby Lowe: Yeah, sure. So again, we are working on getting the final COVID transition guidances posted.

That should be done very soon. That said, the guidances do not trigger that 180 days. We do not have 
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any timeline on that at the moment. That would be an announcement, I believe, from the Secretary of 

HHS giving that advanced notice of terminating the 564 declaration. 

Stacey Moltchanoff: Great. Thank you. 

Joseph Tartal: Our next person up is Ling. Ling, I'm unmuting your line. Please unmute yourself and then 

ask your question. 

Ling Koh: Thanks for taking my question. This is Ling calling from BD. I have a question about multiplex 

COVID and flu assays. In the past, we've heard FDA consistently say that their preference is for assays 

that differentiate between flu A and flu B. But when I was looking through the town hall transcripts, I 

see someone asked a question in January about a pan flu assay, and there seemed to be some openness 

in the response. So I was just wondering if you could comment on that, and whether, as we move 

forward into 510(k)s, if there's a preference between a COVID and flu-A-only assay versus a COVID and 

pan flu assay. Thanks. 

Timothy Stenzel: I'll start this and then see if Kris has anything to add. So there are some technologies 

that just don't have enough channels to report all of the, say, flu A and B, and maybe only can report 

one result and not two. And so we are, again, open to alterations in the pathways, to authorizations of 

tests that are of public health importance. So we would recommend that you come in with your 

technology and explain how you would control any potential risks from not differentiating flu A and B 

and discuss that option with us. Kris, anything else to add to that? 

Kristian Roth: The only thing I'd like to highlight is just the risks. Come in, let us know if you've got 

expert opinion in differentiating flu A and B. We'd love to hear that opinion. Certainly, physicians that 

are in your organization, outside your organization, so that's something that we'd like to know more 

about. 

Ling Koh: Great. Thank you so much. 

Joseph Tartal: Thank you for your question. Up next is Homer. Homer, I'm unmuting your line. Unmute 

yourself and please ask your question. 

Homer Wu: Hi. This is Homer Wu from Hopkins MedTech Compliance. Thanks for taking my call.

Regarding to the final transition plan, my question is, we still have a couple EUA submissions still 

pending approval. So whether FDA is still going to approve any new EUA or go to the-- once the final 

transition plan comes out, we're going to change to 510(k) or something else. 

Toby Lowe: Thanks for that question. So the guidance document does not terminate the 564 

declaration, as we mentioned. So as we've talked about, we are recommending that developers move 

toward traditional marketing submissions. We are continuing to review EUA requests for a small number 

of submissions that meet our current priorities based on the public health needs.

But we are, the 564 is still open, and the guidance document does not change that. And so we'll 

continue to work through the priority submissions that we are reviewing. And every developer with an 

EUA request that is in-house and still open will receive a response either that we are declining to review 
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or declining to issue, or that we are authorizing it, depending on how everything goes. So you will get a 

response. We just can't say what that response will be at this time.

Homer Wu: OK. Just for this question, for the final transition, if that happens for existing EUA, they have 

to change to the full pathway. But since there's no De Novo, so there's only choice to do De Novo? If the 

final test comes out--

Toby Lowe: So we do have-- there are De Novos granted for a couple of device types. If there is not an 

appropriate predicate for your particular device, then yes, it would need to go through De Novo. 

Homer Wu: OK, for antigen, because we only have the PLC antigen. But for the at-home use OTC, there's 

no De Novo, right?. So that's the only choice. 

Toby Lowe: That's correct. 

Homer Wu: OK, thank you. 

Toby Lowe: Yep. 

Joseph Tartal: Thank you, Homer, for your question. Our next question is from Mary. Mary, please 

unmute yourself and ask your question.

Mary: Yes, hello. Actually, my question was already addressed in a previous caller's question, so I no 

longer have a question. Thank you very much.

Joseph Tartal: OK, thank you. And next will be our last question of the day. Stacey, I'm unmuting 

yourself. Please unmute yourself and ask your question.

Stacey Moltchanoff: Hello, this is Stacey Moltchanoff from Thermo Fisher Scientific again. I know that 

there is a COVID transition draft guidance. Will there be any plans to have a similar one for mpox?

Timothy Stenzel: I'll take this. So mpox is a whole lot different than COVID-19. There continue to be, in 

the last few days, 30,000 new cases known in the US, and may underestimate it. And we anticipate that 

COVID-19 will be with us probably for much longer than we hope.

With mpox, there are very few cases. The last time I checked, there was 1.7 cases a day in the United 

States. That's probably a week-old data. And it would be super, super challenging to try to do a 

prospective clinical study anywhere in the world right now for mpox in order to transition EUAs to full 

authorization in an acceptable manner.

So this is the perfect situation for the EUA authorities, where we can keep the 564 declaration in place, if 

we wish, in order that there is still access to testing for mpox. And we do believe that there is a

continued need for mpox, and we want to have tests continue to be available. And in fact, there still are 

some priority categories for EUAs for mpox, and that doesn't include-- the primary category now for 

mpox is really a multi-analyte point-of-care mpox test that includes other commonly-seen and 

potentially overlapping with symptoms and presentation with mpox, STDs. But it is fairly focused and 

limited.
12

But the US government is interested in continuing to have a test availability to keep pressure on keeping 

any sort of potential resurgence mitigated and addressed. So there isn't really a need for transition 

guidance, and we didn't do it for others that are still-- 564 that are open. That includes things like Zika 

and Ebola. And in fact, this year, we've already used the Ebola authorities to make sure that our nation--

and last year-- that our nation has appropriate countermeasures, IVD countermeasures for Ebola 

because of the outbreak that, fortunately, never reached our shores, but needed to be dealt with 

exterior to the US. 

But we needed to be prepared in the US for anything that might happen here. We do a lot of those 

things behind the scenes on a regular basis. And Marburg is up right now, and we're focused on making 

sure that we can deal with Marburg. Hopefully it never hits our shores, but it doesn't hurt to be 

prepared.

So I think that was our last question, and I do want to thank everybody. I do want to give an opportunity 

to all of our experts who are on the call today to say thanks to all of you. So from my heart to yours, 

thank you for all the work that developers had done, and for the positive feedback for this series, and 

for your continued attendance. And it's not goodbye, it's until we meet again. Toby? 

Toby Lowe: Thanks, Tim. I just want to thank everyone for making these town halls so successful. 

Engaging with you all is really the highlight of this experience for me, and this is why I like this job. So 

thank you all for engaging with us and for all of the collaboration that we've been able to have over the 

past three years. We know that will continue even without these town halls, and we look forward to 

continuing to work with all of you as we move forward.

Joseph Tartal: Thank you, Toby. And thank you, everyone, for your participation today. Thanks again to 

our panelists, Tim, Toby, Kris, and Noel. Today's virtual town hall presentation and transcript will be 

posted to the CDRH Learn under the section titled In Vitro Diagnostics and the subsection titled Virtual 

Town Hall Series.

Remember, if you have additional questions about mpox test development, you may send an email to 

MPXDx@fda.hhs.gov. And for additional questions about COVID-19 test development, you may send an 

email to COVID19Dx@fda.hhs.gov. This concludes today's virtual town hall. Thank you all for joining us. 

Have a great day.

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