Transcript: Mpox Briefing


Good afternoon, and thank you for standing by. At this time, all participant lines are in listen-only mode. During the Q&A session, if you would like to ask a question, you may do so over the phone by pressing star one. Today’s call is being recorded. If you have any objections, you may disconnect. It is my pleasure to turn the call over to your host for today, Mr. Benjamin Haynes. Thank you, sir; you may begin.

Ben Haynes

Thank you, Holly, and thank you all for joining us today. We are joined by CDC monkeypox response incident manager, Dr. Chris Braden and White House National monkeypox response Deputy Coordinator, Dr. Demetre Daskalakis. They will talk about new monkey pox vaccine effectiveness data and our call to action as we go into the summer months. Following their remarks, we will be joined for the Q&A by Eli Rosenberg, the Deputy Director for Science in the New York State Department of Health Office of Public Health and author of the New York MMWR. I want to note that this briefing is embargoed till today at 1 p.m. Eastern time, when the reports will go live on the CDC website. I’ll now turn the call over to Dr. Braden.

Chris Braden

Thank you, Ben. Good morning, everyone. And thank you for joining. A year ago today, CDC issued our first report about mpox, then known as monkeypox, in the United States. Since then, more than 30,000 domestic mpox cases were recorded. More than 140,000 specimens were tested, more than 1.2 million doses of vaccines were administered, and more than 6,900 patients were treated with the antiviral Tecovirimat. The mpox outbreak occurred with little warning, peaked in August with about 460 cases a day. Cases declined to an average of about one per day at this point, but the outbreak is not over. And we need to remain alert and continue our prevention efforts.

Today we are here to talk about the latest data we have on the effectiveness of vaccines for the prevention of mpox. New data from three sources – two MMWRs and the New England Journal of Medicine article – support using JYNNEOS as a two-dose series for mpox prevention and incorporating JYNNEOS into a broader program of sexual health services. Data from these studies indicate that JYNNEOS provides substantial protection against mpox regardless of how it was administered or whether the recipient is immunocompromised. One study used case and control data from 12 jurisdictions, one from just New York and the third included national data from electronic health records. Vaccine effectiveness estimates from these studies ranged from 36 to 75% for one dose and 66 to 86% for two doses of JYNNEOS vaccine. And all routes of administration, that is subcutaneous or intradermal, provide similar protection.

These studies conducted over the past year reinforce the importance of receiving two doses for the optimal protection. While more than 1.2 million people have received at least one dose of JYNNEOS, less than a quarter of at-risk population at risk has been fully vaccinated. The data also shows there is wide variation in vaccine rates by jurisdiction and among those who would receive the most benefit from the vaccine, meaning the chances of a renewed outbreaks go up when fewer people have been vaccinated. Earlier this year, CDC released projections that foreshadowed the risk of mpox resurgence is higher in jurisdictions with low vaccine coverage. Jurisdictions with less than 35% coverage of at least one vaccine dose are more likely to have outbreaks which could be as large or even larger than those in 2022.

And while the World Health Organization recently declared the outbreak no longer represents a public health emergency, a cluster of mpox cases occurred in Chicago, demonstrating the ongoing risk for new cases and outbreaks and the need for continued diligence and prevention efforts. Now I’ll turn it over to Dr. Daskalakis to talk about what we know about the cases in Chicago and what action people at risk can take as we head into the summer.

Demetre Daskalakis

Thank you so much Dr. Braden, and this is Demetre Daskalakis. Earlier this month Howard Brown Health in Chicago and the Chicago Department of Health announced that they had detected a cluster of mpox cases, with updated reports indicating now that 21 people have been diagnosed with mpox as part of this cluster. So far, most of the cases that have been reported have been in men who identify as gay or bisexual, and all have had mild symptoms.  What’s really unique about this cluster is that most of the cases are in people who have had one or both vaccine doses.

Right now, we don’t know why people in this cluster of cases have gotten mpox after vaccination. There are a number of possible explanations and what’s important is that CDC staff are assisting the Chicago Health Department to help find answers.  We also don’t know if immunity after vaccination decreases with time or how long the vaccine protects against mpox infection. Several ongoing studies are looking at this issue, and we will be examining data from these studies closely for clues. What we do know is that vaccination makes getting and spreading mpox less likely and may decrease the chances of severe illness, hospitalization, and death. And as Dr. Braden mentioned, earlier this year CDC put out some very important modeling toward that asked the question how high the vaccination rate needs to be in a city to prevent mpox outbreaks. What that modeling found is the more immunity that we have in the community, the lower the chance is it will have any outbreaks. Higher vaccination rates equal lower risk for an outbreak.

So even though no vaccine is perfect, even imperfect immunity in many people means a lot of immunity in the population. And then the result is that we are less likely to have any outbreaks at all. However, without renewed prevention efforts, especially vaccination, we are at risk for a resurgence of mpox. This is especially a concern as we approach summer with planned gatherings that may have high potential for skin-to-skin contact or that are associated with increased sexual activity. Most new cases are in gay, bisexual, and other men who have sex with men, and transgendered and non-binary people. A disproportionate number of cases have been among Black and Hispanic or Latino men.

So, my charge to those in the LGBTQ+ community who have not been fully vaccinated – now is the time. And get your second dose if you haven’t. Seek health care and get tested if you have a rash even if you have been previously vaccinated or had mpox. We need to be ready to use all the tools in the mpox prevention toolkit, including vaccine, testing, and information so that people can make informed decisions about their sex lives to halt the spread and protect their health and the health of the community. Getting summer ready means mpox vaccination, but that’s not all it means. It means being up to date on all your sexual health and that includes HIV and STIs like syphilis, gonorrhea, and chlamydia. With that, I’ll turn it back to Ben. For we can turn it over to some questions, Ben.


Thank you, Dr. Holly, we are ready to open up for questions.


Thank you. If you would like to ask a question. Please unmute your phone, press star one and record your first and last name slowly and clearly when prompted, so I may introduce you. To withdraw your request, please press star two. Again, to ask a question. press star one. Our first caller is Spencer Kimball with CNBC. You may go ahead.


Thank you. I have a question about the vaccine estimates and these studies. Like y’all were saying, in the New England Journal of Medicine studies, 36% for one dose 66% for two doses; and in the MMWR I think it was 75 and 85. So that’s a pretty big range, particularly when it comes to the first dose. Can you just explain why there is such a wide range in these estimates? What was different between the studies? Thank you.

Chris Braden

Chris Braden, speaking. I’ll take a stab at that question. Thank you, and it’s a very good one. The first thing I would like to point out is that it’s advantageous to have multiple studies to understand what vaccine effectiveness really is in the population. So these are three different studies that we’re publishing today. Each has a different data source, they have different methods, and a different source of the data that they’re looking at, in their, in their methodology.

So we need the different types of studies looking at data in different ways in order to come to probably a combined estimate that looks at across these studies, to come to what may be the best estimate of vaccine effectiveness. The other thing I would like to point out, and this is especially true for the two doses, is that each of the estimates is within the confidence intervals of each individual study. So statistically, they’re not all that different. But I do get the issue that especially for the New England Journal of Medicine study, that the estimated estimate is lower than in the other studies. A couple of things about the New England Journal of Medicine study, I think, to point out, it is a strong study in that it has a lot of power in the number of cases and controls that were involved using a national database of anonymized medical records. The other thing about the New England Journal of Medicine study is that all the eligible cases and controls were included in the analysis. The other case control studies depended upon the voluntary provision of information from cases and controls to be able to include the data and analysis. And that volunteering, that aspect of volunteering can introduce some bias to the estimates, either underestimating or overestimating the vaccine effectiveness.

The other thing that I would like to point out is that we still don’t know enough about the effect of this vaccine in the population of immunocompromised patients. And if you look at the New England Journal of Medicine article, when they did a secondary analysis, when they excluded immunocompromised persons, the vaccine effectiveness for two doses actually went from 66 to 76%, more in line with what we see with the other studies.  We need to know more about the vaccine effectiveness in that group, and it’s an important group to study in our additional studies. I’ll leave it at that and see if there’s anybody else that has comments.

Eli Rosenberg

This is Eli Rosenberg in New York. I’ll just add my endorsement of that. In those remarks. We here in public health really, you know, we often rely on triangulation from multiple data sources to arrive at truth. And that’s really the case for these three studies. Here in our, you know, our study today, and MMWR really echoes the findings of the other two, particularly the other one in MMWR, finding up to 88% effectiveness for two doses. And that study is using all reportable data in New York for both cases and immunizations outside of New York City. So, I think everything that we’ve just said was really quite spot on. And these are all really quite statistically similar and compatible estimates.

Demetre Daskalakis

That’s just gonna add a quick thing on top of the excellent comments that Chris and Eli made, which is this is this is it’s not atypical in other areas to think about different sort of approaches and studies to model how something functions. So thinking about weather, like you use different models to identify like, what weather patterns are going to be like. And so different methodologies mean different views, and they do inform us in the same way, which is one dose is good and two doses better. And it’s also important to remember that this really focuses on prevention of infection and even beyond the vaccine effectiveness measured with those outcomes is the sort of other issue: that we see reduction in some of the adverse outcomes of mpox, which makes this really important. So as our weather forecast, this definitely tells us that these vaccines work and that our strategy of vaccinating people and getting both doses really remains core to our efforts to prevent mpox. Thanks.

Ben Haynes

Next question please.


Our next caller is Martin Espinosa with Press Democrat, you may go ahead.


Hi! Can you hear me? Okay? Oh, yeah, one of the speakers spoke to this with regard to the effect of the vaccine on the population of immunocompromised. Do we know Do we have any information about the 21 in Chicago, whether we know the majority of them were immunocompromised?

Demetre Daskalakis

I’ll start, Chris. And maybe you can if there’s other data that you want to share. So I think that what we know from Chicago is that, you know, we I think that the investigation is still ongoing. And I think that we do have some folks within the cluster who have pre-existing conditions that could qualify them for immunocompromised, but many of them are under very good control. So I think as the investigation unfolds, we’ll learn more. But there at least on surface does not seem to be a specific trend, from the perspective of the immune status of the individual. That seems as if it’s not a player. Chris, I’m not sure if you have anything to add there.

Chris Braden

No, I think that’s right. And one of the questions that we get asked quite a bit is whether or not these cases that had previous vaccination, were also co-infected with HIV. And some of them were of the 21 cases. We know by that were also infected with HIV, but they were well controlled. And what we know so far, looking at some of the information about the vaccine effectiveness, is that for people who have HIV well controlled, the vaccine is still quite effective in that population.


Our next caller is Alexander Tin with CBS News. You might go ahead.


Hi, thanks for doing that. Dr. Braden, you mentioned that combined estimate, can you clarify what you think that combined estimate is right now, based on these studies? How does that change your risk assessment and modeling? And Dr. Daskalakis? You mentioned those ongoing studies, what are the chances you think that additional boosters might be greenlighted this summer, like for men who only got intradermal or ACAM2000?

Chris Braden

So I’ll take the question about the combined estimate. And I’m what we take away from these three studies is that the vaccine effectiveness is substantial. And that two doses is definitely better than one. That being vaccinated will help decrease the spread of mpox in populations. It will help individuals prevent the acquisition of mpox, and it will help individuals avoid severe disease or even death, or those that are that are susceptible to very severe disease. So there’s a number of things that we can take away from these three studies that I think are very important in that way.

Demetre Daskalakis

Hi there it’s Demetre. I’ll take the second part of the question, which is, I think what’s really important is that we have the studies that are ongoing to really ask some of the questions around durability of vaccine. And so I think we’ve already — really immediately after seeing, through the Chicago cluster — convened folks within the U.S. government to discuss what the data is that we have and if there needs to be any change in vaccine strategy. I just want to clarify one quick thing: There is no current change in vaccine strategy. And I want to just again, emphasize that, as you heard from Dr. Braden, there’s no difference between the subcutaneous and intradermal in terms of its vaccine effectiveness, and the studies that were that will be released today. So there’s specifically no indication for folks if they’ve gotten two doses of vaccine at this time to get any additional doses. So I think the exciting news is that we are like on it from the perspective of having the scientific discussions, and are obviously, as sort of demonstrated in the track record of the response, really adjust our strategy based on what science is showing us. And so I think we’re really in that learning more about Chicago and making sure we maximize what we know about vaccines so we can make informed decisions. Thank you so much for your question.


Next question, please.


Our next question is from Christopher Kane with Washington Blade. You may go ahead.


Hey, I really appreciate your taking my question on. Dr. Demetre, I’m wondering if you’re discussing the fact that that we’re going to see perhaps an increase the risk this summer of have new outbreaks, is there anything you can preview in terms of whether our federal health agencies are going to administer like vaccine drives or outreach initiatives that Pride celebrations and that kind of thing?

Demetre Daskalakis

Sure, it’s a great question. So we’ve been on a really a world tour, as I like to call it in the U.S., really focusing on organizers of events, including folks who really are the umbrella organizations for a lot of the Prides including some specific Black prides and are working really closely with CDC to be able to make linkages in the in the event that, that there is interest to actually have a vaccine affiliated with events. So I think that, you know, we, we are really working on the matchmaking side of this. We have vaccine and we have willing organizations to do it. We have resources from the perspective of the flexibility built into HIV and STI funding to allow for this work as well as the crisis COAG which – a cooperative agreement – that provided even more resources locally for such efforts. So the answer is yes. So I think we are really poised to make sure that we’re promoting the possibility of vaccination affiliated with events, and really working with organizers and local public health to see where those opportunities exist and where they make sense. Thank you for your question.


Next question, please.


Our next caller is Mike Stobbe with the Associated Press. You may go ahead.


I, thanks for calling on me. I want to ask you, you said earlier that about one quarter, less than one quarter, of those who are fully at risk or those who are at risk or fully vaccinated? Can you tell us the denominator are the most recent denominator? Like, what is that 1 million or 1.5 million? I’m just trying to get to how many people in America are fully vaccinated at this point? And could you also discuss vaccine supply going into the summer? Like how many doses are available? And how have you distributed them? Thank you.

Demetre Daskalakis

Yes, sir. So the estimates that are made for the denominator really are stable from our previous discussions of them. And so the denominator is an estimate. It is based on HIV surveillance data as well as surveillance data around pre-exposure prophylaxis eligibility in the U.S., mainly among gay, bisexual, and other men who have sex with men. In addition to that, because of the recommendation that partners are also included in the sort of vaccine eligibility, there’s also a correction factor of about 25%. So the estimate – all comers – all comers are men who have sex with men who could benefit from HIV pre exposure prophylaxis, plus men who have sex with men who are living with HIV, with that 25% correction factor really takes us to a denominator of about 1.7 million individuals who can benefit from vaccine. I will then take the question of supply. So I’ll just start by a very different place in vaccine supply than we were in in spring summer 2022. So with the introduction of intradermal dosing, we’ve able been able to extend what supplies we do have by making each individual vial a multi dose vial. We have worked with the company that produces the JYNNEOSs vaccine to increase production, and have also created a fill and finish facility in Michigan to actually make sure that we have domestic fill and finish vaccine that has that site has cleared FDA for that vaccine produced at that site is now in the Strategic National Stockpile. As it stands today, there is a vaccine that’s been distributed almost a million vials, some of that is still out on the edges, with jurisdictions and still available for order is about 400,000 vials with the potential of going deeper into the supply if indicated or necessary. So I think that, that in terms of supply, like I said, because of the multiple domains of work to increase vaccine supply, I think that we’re in a really good position to make sure that we cover the folks who could benefit from vaccine. Thank you.


Next question, please.


Our next question is Matthew Chase with Newsday. You may go ahead.


Thanks for taking the question. Can you guys in simple terms, provide the percentages about whether the vaccine just mitigates the effects of disease protects the vaccinated person from having any symptoms whatsoever? Protects the vaccinated person from getting the virus or totally stops infection and both the vaccinated person and an exposed second or third or other person? And also, what method are you using to give the vaccine? Are you still stretching it? Or are you going with the original method?

Chris Braden

So I’ll jump in; this is Chris Braden. And thank you for that question is very insightful, because I think it’s worth emphasizing that the vaccine effectiveness estimates that we’re talking about today is for symptomatic infection that’s been basically attended by a medical system. So that vaccine effectiveness is really specific to that situation. When you talk about vaccine effectiveness, for severe disease, it’s a different calculation. And we would estimate that vaccine effectiveness for more severe disease is actually higher than for any disease. Because we have other information that would tell us that vaccination, even if you are infected and have some illness, it’s going to be less severe if you’ve been vaccinated. So the other type of vaccine effectiveness that you talked about is effectiveness in preventing spread. And that’s a different calculation. And it’s actually one that is very difficult to study. So that’s one where we don’t have a lot of information about vaccine effectiveness to prevent the spread of, of the virus. So we need to be cognizant about what we’re actually talking about when we talk about these particular vaccine estimates that that are being published today. The second question was, repeat that please.


Are you using the original method? Or are you still stretching it to get the five doses?

Chris Braden

Yes. Okay. So the, the original method was the subcutaneous dosing. And then the intradermal dosing is a smaller dose so you can get more doses out of a vial. So it is advantageous to be able to use the smaller dose if it provides more vaccines and more people. But it is up to the preference of the provider and the patient as to which route they actually receive.


Our next question?


Next question is from Tom Wray with Illinois Eagle. You may go ahead.


Yes. My question is, is the CDC doing any outreach to local health departments outside of large cities? Or what kind of outreach they’re doing? Because we did see cases outside of Chicago here in Illinois?

Demetre Daskalakis

So, I can speak for at least the White House outreach. So, we definitely have been doing outreach beyond just cities. I think that we routinely are having meetings and have done, so actually, for the duration of the response, with health departments that really represent like states, not just cities. So through various organizations, like CSTE, ASTHO, as well as work that focuses on big cities. The other the other pieces that the outreach that we’ve conducted with providers, as well as organizers of events really have spanned both large, medium, and small cities as well as rural spaces as well. So I think I think that definitely, we continue on that same path that we’ve really been on since the beginning of the outbreak and have really intensified really in the last two or three months those conversations in various types of jurisdictions, as we prepare for spring summer, just realizing again, that people who may not be in a city may go to a city for events. And so all of that has been a part of what we’ve been talking about. Additionally, we’re doing pretty significant outreach to medical providers, and I think you’re going to see more of that today with letters to providers, reminding them to review their lists of humans who could potentially benefit from vaccine and if they are not vaccinated, recall them to make sure that they get vaccinated. So I think, yeah, the short answer to the question is yes, and we have really been doing so in terms of outreach since the beginning of this outbreak. Chris, it was a specific, a CDC specific dynamic, anything that you have to add there on this question.

Chris Braden

I would just say that, you know, and CDC has been able to support a number of jurisdictions, both in cities or in counties, or in entire states, where they are planning for the prevention activities, promotion of vaccines, etc., through a number of different types of support, including grants to, to jurisdictions and to community-based organizations. So, trying to do a force multiplier efforts to be able to support as many jurisdictions as possible with both funding and technical support going forward.

Eli Rosenberg

I just wanted to add one thing to the previous question, because we didn’t get to sort of the plain English interpretation. And it wasn’t sure if I could just jump in, if that would still be helpful.

Okay, great. So I think was the point it was just the, as Dr. Braden just clarified, these studies were looking at the prevention of sort of a diagnosed infection and medically attended symptomatic kind of infection. But when you look at the numbers, we see really important signal of what the preventive power here is. Depending on the picking on the two MMWR studies, you know, 86% or 88% vaccine effectiveness for two doses means that if you take a vaccinated person compared to an unvaccinated person, we’re estimating that during this outbreak last year, that they had about an 86 or an 88% chance lower chance of acquiring symptomatic mpox. And that’s that was diagnosed. That’s just remarkable prevention, a real incredible level of prevention but it’s already been discussed on this call it’s not 100%. And so yes, 88% 86% is incredible. But sometimes we might expect what would have sometimes been called a breakthrough infection, or essentially a situation where a vaccine hasn’t provided protection. And that’s why we say that this is an important layer of protection on top of all the other prevention strategies that we’ve all been messaging about. So, I think that that’s sort of the important piece very, very high protection for vaccinated people compared to an equivalent unvaccinated person.


Next question, please Holly


Next question is from Lynn Peterson with Trends in Medicine, you may go ahead.


Can you give us some more details, please about the 21 patients? It’s not severe. But if any of them has to be hospitalized. What kind of outbreak? How is it diagnosed? Just to more depth on that, please.

Demetre Daskalakis

Chris, I’ll start and then I’ll hand it over to you so so that the 21 cases, as you’ve heard have been very mild. To date we’ve not heard of hospitalizations, which is great news. We’re also hearing that, that the mucosal symptoms or the painful involvement that we tended to see in the outbreak, before sort of rectal symptom, that that’s been very limited, and the folks in this cluster. Additionally, like even the number of lesions that they have, also appears to be smaller, at least in the initial review of the individuals who were who had mpox after vaccination. So I’ll say that, again, the CDC continues to do the investigation and so we’re going to learn more, and I’m sure Chicago will also share more as they learn more as well. But I think the the overarching message, at least anecdotally so far, is that we’re seeing very mild disease. Chris, Did I cover that? Okay.

Chris Braden

Yes, he did. Thank you.


All right. And our last question comes from Benjamin Ryan with NBC News. You may go ahead.


Hi, everyone. I’m wondering about what kind of research you’re doing into the potential for waning immunity from either previous infection or vaccination.

Chris Braden

This is Chris Braden, thank you for the question. And it really is a central issue. And we are we are looking into this in a number of ways. At CDC we have three current ongoing studies: one where mpox has been endemic for a long time in the Democratic Republic of the Congo, where they’ve had a a trial using the JYNNEOS vaccine now for some period of time, but also in the current outbreak, we have studies ongoing in Washington, DC, and Los Angeles. We hope to be looking at some of the early data on those studies soon to see if we can identify any clues, or hints that the antibody levels for instance, are declining, which may indicate that there’s some waning immunity. But we don’t have that information yet, especially for the patients in the United States. They just haven’t been vaccinated for that long. So but we’re going to be looking and interrogating that data as soon as we can to get some clues about what may be happening. But I will also say that when we look at the cluster in Chicago, for example, and unexpected proportion of cases that were previously vaccinated. That’s only one of the potential reasons why we could be seeing that, you know, phenomenon. Certainly, will be we’ll be looking at it. But also we need to look at whether or not the virus has changed to overcome immunity and we’re going to be doing some genome sequencing of the viruses. From the individuals that are involved with that cluster and continue to look at that sequence information from cases from across the country. We also need to look to see whether or not the specific vaccine lot or doses used were compromised in some way, or whether they were handling errors or whether they were administered in some way that was flawed and didn’t induce the immunity in that way. And there are still other reasons why we might see a number of people who had mpox were previously vaccinated that we’re looking into. So just realize that we need to continue to this investigation to really know what’s going on.

Ben Haynes

I’d like to thank everyone for joining us today. If there are follow up questions, please call the press office at 404-639-3286 or you can email And as a reminder, the contents of this briefing are embargoed until 1pm today Eastern, when the reports will be posted online. This will conclude our call.


And this concludes today’s conference. Thank you for participating you may disconnect at this time.

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