Via Teleconference
11:09 A.M. EST
MR. ZIENTS: Good morning, everyone. And thanks for joining what is a phone briefing today. We expect to return to our regular format next week.
Today, Dr. Walensky will provide an "Omicron in the U.S." update and discuss CDC's updated guidance for people who test positive for COVID.
Dr. Fauci will discuss the latest science on Omicron.
Before we turn to the doctors, I thought I would provide a brief update on the actions the administration is taking to ensure states, communities, and hospitals have the support they need in the coming weeks.
For months, the Biden administration's whole-of-government surge response teams have been working hand-in-hand with governors and local health officials across the country to assess and address needs on the ground.
More than 13,000 National Guard members have been activated in 48 states to support the COVID response, from vaccinations, to testing, to clinical care. These are state deployments that, thanks to the President's actions, are fully paid for by the federal government.
Additionally, we have directly helped more than 30 states and territories by deploying over 2,100 federal personnel and thousands of ambulances, ventilators, and other critical supplies.?
On Monday, the President joined the administration's regular meeting with governors - it was actually our 40th meeting this year - to reiterate that we continue to stand ready to help them with more support for hospitals, more testing, and more capacity to get shots in arms. This includes an additional 1,000 military doctors, nurses, and EMTs ready to deploy when and where needed.
Our message to governors around the country is simple: If you need something, say something. And we will mobilize to quickly get you the resources you need.
And that's exactly what we've done over the past week or so. More boots and supplies have already landed on the ground. For example, in New York, 60 FEMA medical personnel and 30 ambulances arrived last week to help transport patients to hospitals around the state and balance patient loads. And in just one week, we had established nine federally run testing sites in New York City with three more sites opening this Sunday.
In Arizona, 20 FEMA paramedics began providing clinical support across the state on Christmas Eve, with nearly 40 more medical personnel arriving next week to help administer treatments in Maricopa and Pima counties, as well as in Tribal communities.
In Indiana, 23 military medical personnel started their mission on Christmas Day at University Methodist Hospital in Indianapolis.
In New Mexico, 15 medical personnel from the U.S. Public Health Service Commissioned Corps arrived on Monday to provide surge support in Indian Country. Today, we're sending 15 ventilators to the state, and 12 federal medical personnel will arrive next week to help get more shots in arms.
In Wisconsin, a 23-person military medical team is scheduled to start its support mission at Bellin Hospital in Green Bay on Friday.
In New Jersey, a new federally run free testing site will open New Year's Day.
And more sites will open across the next several days in Philadelphia and Washington, D.C.
And on top of all of this, a million gloves; 342,000 masks, respirators, and face shields; and 40,000 gowns the administration has shipped for frontline healthcare workers in states in the past couple of weeks alone.
So, as you can see, we've been working around the clock to surge reinforcements to communities as they battle Omicron, helping to staff hospitals, administer monoclonal antibody treatments, transport patients, add testing capacity, and get more PPE to where it is needed.
And you'll see us continue to act aggressively to address communities' needs in the days and weeks ahead.
So, with that, let me hand it over to Dr. Walensky.
Dr. Walensky.
DR. WALENSKY: Thank you so much, Jeff. Good morning, everyone. I'd like to start by walking you through today's data.
The current seven-day daily average of cases is about 240,400 cases per day, an increase of about 60 percent over the previous week.
The rapid increase in cases we are seeing across the country is in large part a reflection of the exceptionally transmissible Omicron variant. In a few short weeks, Omicron has rapidly increased across the country and, we expect, will continue to circulate in the coming weeks.
While our cases have substantially increased from last week, hospitalizations and deaths remain comparatively low right now.
The seven-day average of hospitalizations - admissions is about 9,000 per day, an increase of about 14 percent over the previous week. This could be due to the fact that hospitalizations tend to lag behind cases by about two weeks, but may also be due to early indications that we've seen from other countries like South Africa and United Kingdom of milder disease from Omicron, especially among the vaccinated and the boosted.
And the seven-day average of daily deaths are about 1,100 per day, which is a decrease of about 7 percent over the previous week.
As you continue to watch these trends, I want to emphasize that this virus has proven its ability to adapt quickly, and we must adapt with it. And it is in that context that, last week, CDC updated our isolation and quarantine guidance for healthcare workers as we prepare for an anticipated surge in COVID-19 cases.
This updated guidance will help to ensure that hospitals, clinics, and long-term care facilities can safely stay open and remain appropriately staffed, both to handle hospitalizations from COVID-19 and to make sure that we continue to provide the necessary care for those experiencing heart attacks, strokes, and other illnesses.
Swiftly thereafter, on Monday, CDC also updated its recommendations to shorten the recommended isolation and quarantine period for the general public.
These updates to our recommendations were made to reflect what we currently know about COVID-19 infection, including how long a person is most infectious. Studies have demonstrated that when infection with SARS-CoV-2 - people are infected with SARS-CoV-2, people are most infectious in the one to two days before symptoms develop and the two to three days after. After five days, the risk of ongoing transmission substantially decreases.
Let me make clear that we are standing on the shoulders of two years of science, two years of understanding transmissibility, and a lot of information that we have gleaned from the wildtype virus, as well as the Alpha and Delta variants, and more that we continue to learn every single day about Omicron.
We do know the vast majority of viral transmission happens in those first five days, somewhere in the 85 to 90 percent range. So if a person can isolate for the first five days, they absolutely should.
Many are asking why do we not require a test at the end of the five days of isolation for those who are infected. We know that PCR testing would not be helpful in this setting, as people can remain PCR positive for up to 12 weeks after infection and long after they are transmissible and infectious. We also don't know that antigen tests give a good indication of transmissibility at this stage of infection. On the other hand, we know that after five days, people are much less likely to transmit the virus and that masking further reduces that risk. And this is why people need to mask for five days after their five days of isolation.
This science, as well as what we know about the protection provided by masking, vaccination, and booster doses, and about our test performance, were all part of what informed our updated recommendations.
Let me walk you through exactly what these new recommendations mean for you:
First, isolation refers to what you should do when you have COVID-19, most likely diagnosed by a positive test. Isolation prevents those who are known to be infected from transmitting the virus to others.
Quarantine, on the other hand, is different. This is what you do when you have to be - when you've been exposed to someone who has disease and are unsure if you, yourself, were infected.
Quarantine prevents further spread of the virus in the time before someone may develop symptoms or from those who are asymptomatic from their infection.
If you are infected with SARS-CoV-2, regardless of your vaccination status, you should isolate for five days.
During periods of isolation, it's best for you to wear a mask around those in your household to avoid spreading the virus at home.
After five days, if you're asymptomatic or if your symptoms have largely resolved, you may leave isolation, as long as you continue to wear a mask around others, even in the home, for an additional five days.
For those who have been exposed to COVID-19, quarantine recommendations are based on your vaccination status.
If you are boosted or have been vaccinated with your Pfizer or Moderna series in the past six months or your J&J shot in the past two months, no quarantine is needed. However, a mask must be worn for 10 days following your known exposure, and we also recommend getting a test on day five after your exposure.
If you're not vaccinated or you were vaccinated with your Pfizer or Moderna series over six months ago or with J&J over two months ago and have not yet received your booster, you should quarantine for five days following your last exposure. After five days, you should continue masking around others for an additional five days and you should also get a test at day five.
If it's not possible for you to quarantine, it is really important that you do the right thing and wear a mask at all times around others for 10 days after your exposure. Here, we also emphasize that you should get a test at day five.
And if at any point you develop symptoms of COVID-19 during your quarantine period, or your 10 days after exposure, like fevers, runny nose, a cough, headaches, or body aches, you should get a test and isolate until your test results return. And, of course, then isolate if your test returns positive.
Now, with these updates to our isolation and quarantine recommendations, I want to emphasize the critical importance of masking, which we know decreases the risk of transmission, as well as the importance of staying home when you're sick. If you are sick or have symptoms, it is best for you to stay home and to stay away from others.
As we continue to fight COVID-19, prevention is truly our best option. This means for everyone five and older, getting vaccinated. And for those eligible, it means getting your booster shot. (Inaudible), it means continuing to follow our multi-layer prevention measures, including masking in public indoor settings in areas of substantial or high community transmission, washing your hands frequently, and testing before gathering when possible.
How well each of these prevention measures is implemented, as well as adherence to isolation and quarantine recommendations, will determine the outlook in the coming weeks and months.
We, at CDC, are working to provide updated recommendations, using science to ease the burden of lengthy isolation and quarantine recommendations. However, these recommendations will only work if people follow them.
As we look to the new year, I am hopeful that we can come together and do what is in the best interest of our loved ones, our friends, and our communities.
So, with that, I say: Thank you, Happy New Year, and I will now turn things over to Dr. Fauci.
DR. FAUCI: Thank you very much, Dr. Walensky. I'm going to concentrate my remarks predominantly on severity or not of this disease.
But before I do, I just want to underscore something that we always talk about when we talk about severity, and that is the issue of transmissibility and immune evasion.
So, very briefly, we know now incontrovertibly that this is a highly, highly transmissible virus. We know that from the numbers we're seeing. But I think each individual person throughout this country is now seeing around them the high degree of transmissibility.
With regard to immune evasion, very clearly now we have a number of tests looking at the effect of Omicron on the evasion of immunity from monoclonal antibodies as well as from vaccine-induced antibodies. And clearly there is a degree of immune evasion, particularly against infection and to some degree against hospitalization.
However, importantly, and the bottom line message here, is that boosters bring back up that degree of protection to a level that is approximating what it was before.
So, boosters are critical in getting Our approach to Omicron to be optimal.
Now let's focus on the severity of disease. I'm going to review some preliminary observational clinical data, as well as some selected initial laboratory data.
First, the data from South Africa. There have been a number of reports. I'll report here one published yesterday from a large hospital in the Tshwane South African district added to an earlier report that is very similar.
COVID-19 hospital admissions from the Omicron wave were compared to admissions from previous waves. And here is the comparison:
On hospital deaths: 4.5 versus 21.3. ICU admissions: 1 percent from Omicron, 4.3 for others; 45 percent of patients required supplemental oxygen with Omicron compared to 99 percent in a prior wave. Length of study, four day - length of stay, excuse me: four days for Omicron, 8.8 days for the second wave. Mean average age: 39 years for Omicron, 49 years for previous waves.
The authors note in that study that the changing clinical presentation of SARS-CoV-2 is likely due to the predominantly high level of prior infection and, to some extent, vaccination coverage, since vaccine level is relatively low in the Republic of South Africa.
Moving on to the United Kingdom: In a study of the UK Health Security Agency technical briefing, preliminary analysis was looked at from days November the 22nd through December the 19th. The risk of presentation to emergency care or hospital admissions with Omicron was 60 percent that of Delta. The risk of hospitalization admission alone with Omicron was 40 percent of that for Delta.
These data were fortified by data from Scottish researchers that showed when analyzed data in the Scottish population from November 1 to December the 19th, preliminary data suggest that Omicron is associated with a two-thirds reduction in the risk of COVID-19 hospitalization.
Another study from the UK - Imperial College UK report in the hospitalization risk. Analysis of both clinical and laboratory data indicate an overall significant reduction in the risk of hospitalization for Omicron compared to Delta.
In the United States, we are getting accumulation of data. The spike in cases is out of proportion to the increase in hospitalization.
So, if one looks at 14-day averages, the data, as of last night, indicate a plus 126 percent increase in cases and an 11 percent increase in hospitalizations.
Now, we must remember that hospitalizations and deaths are lagging indicators. However, the pattern and disparity between cases and hospitalization strongly suggest that there will be a lower hospitalization-to-case ratio when the situation becomes more clear.
Just a word about children: Certainly, more children are being infected with the highly transmissible virus, and with that, there naturally will be more hospitalizations in children.
It is noteworthy, however, that many children are hospitalized with COVID as opposed to because of COVID, reflecting the high degree of penetrance of infection among the pediatric population.
The final conclusion about the level of severity in children remains to be determined.
And finally, some in vitro and animal data which addressed the issue of whether or not there is inherent lowering of virulence of the virus. In a study from Hong Kong, it was shown that although Omicron replicates faster than Delta in the bronchus, there's less efficient replication in the lung.
Hamster models from the University of Tokyo show that Omicron poorly infects and spreads in the lung and is less pathogenic compared to Delta in a hamster model. Belgian researchers in Syrian hamsters see the same thing.
NIH-funded studies that are ongoing right now in both mouse and hamsters confirm the lesser virulence in the animal model. And studies here at the Vaccine Research Center at NIH, in the nonhuman primate model, are ongoing and will await results of that.
So, in conclusion, the data are encouraging but still, in many respects, preliminary; yet they are getting stronger and stronger as additional data are accumulated. And it is still unclear how these data will translate to other demographically diverse populations in the United States and elsewhere throughout the world.
But having said this, all indications point to a lesser severity of Omicron versus Delta. It is difficult to determine what degree of lessened severity is due to preexisting immunity or the intrinsically lower virulence of Omicron, as suggested by the animal studies, or a combination of both. Increased transmissibility of Omicron resulting in an extremely high volume of cases may override some of the impact of the lower disease severity.
And so we should not become complacent since our hospital system could still be stressed in certain areas of the country.
And so, to repeat what we say so often and that deserves reemphasis: The risk of severe disease from any circulating variant, including Omicron, is much, much higher for the unvaccinated. And so, adults and children who are eligible: Get vaccinated. And vaccinated people: Get boosted when eligible.
Back to you, Jeff.
MR. ZIENTS: Okay. Well, thank you, doctors. And let's open it up for some questions.
Over to you, Kevin.
MODERATOR: Thanks, Jeff. And let's try to be as efficient as possible so we can get through as many questions as people have.
First, let's go to Ricardo at the AP.
MR. ZIENTS: Ricardo.
Q Okay, can you hear me now?
MR. ZIENTS: Now we can, yes. Thank you.
Q Okay. Sorry about that. That was a little slow there.
Yes, I'd like to ask Dr. Walensky what share of the infections that we're seeing now are accounted for by people - are breakthrough infections, basically. So, what proportion of the cases we're seeing now are breakthroughs? Same for hospitalizations - what proportion are breakthroughs?
And for Dr. Fauci, do you think that we're going to need a fourth shot - another shot just to keep something like Omicron, or whatever might be coming next, at bay?
MR. ZIENTS: Okay. So, Dr. Walensky and then Dr. Fauci.
DR. WALENSKY: Yeah, thank you, Ricardo, for that question. What I can tell you is that compared to people who are un- - to who are boosted: If you are unvaccinated, you are 10 times more likely to be a case and 20 times more likely to be a fatality; compared to people who are unvaccinated, you are 17 times more likely to be in the hospital.
So, our vaccines are working really well to prevent severe disease and hospitalization and death. They're actually also working quite well to prevent cases, although we do know more breakthrough cases are happening in the context of Omicron.
MR. ZIENTS: Dr. Fauci?
DR. FAUCI: Yes. Thank you for that question, Ricardo. Before we start talking about a fourth shot, it will be very important for us to determine the durability of protection, particularly against severe disease for the third shot booster of an mRNA and the second shot of a J&J. Right now, we don't have that information.
It is conceivable that in the future we might need an additional shot, but, right now, we are hoping that we will get a greater degree of durability of protection from that booster shot.
So, we're going to take one step at a time, get the data from the third boost, and then make decisions based on the scientific data.
MR. ZIENTS: Next question.
MODERATOR: We'll go to Laurie Garrett.
Q My question is to Jeff. Over the last year and a half, roughly, we've seen a steady escalation in attacks directed personally against Dr. Fauci and generally against public health leadership, including death threats. And this has escalated to the point where we now have actually had Jesse Watters call upon his followers in "Fox News land" to, quote, "ambush" Tony and his family, and to, quote, take "the kill shot." And then this was backed up by Steve Bannon.
We've had Lara Logan say to her followers that Tony is "Josef Mengele" and should be handled accordingly, and so on.
And all over the country, public health leaders are getting death threats; they're getting threats against their families. And we have not heard a peep from the President, from the White House, from members of Congress on the Democrat side in the defense of these individuals, or nor have we heard anything about the Department of Justice issuing indictments. Is it now legal to yell in public that people should kill and ambush federal health officials?
MR. ZIENTS: Well, we've talked about disinformation in these types of threats as being completely and utterly unacceptable.
The President has been very clear about how much of an impact this type of misinformation is having on the country. So, all I can say is that Dr. Fauci is an extraordinary public servant, as are the whole team of public healthcare professionals in the federal government, across state and local governments. They're doing their jobs. And this type of disinformation and these types of threats are completely and utterly unacceptable.
MODERATOR: Next question, let's go to Sabrina Siddiqui at the Wall Street Journal.
Q Yes, thank you so much for doing this. I know that there's going to be a clear distinction here between people who are unvaccinated and those who are vaccinated, but when you're looking at the vaccinated and boosted population, is it still your goal to minimize COVID cases across the country? Or at this point, is it more about preventing further disruptions and learning how to live with the virus?
It would be helpful if you can just kind of articulate where we are at this stage of the pandemic with respect to transmissibility and the expectation that many more people, even those who are vaccinated and boosted, will likely be infected with Omicron.
MR. ZIENTS: Dr. Fauci, do you want to first here?
DR. FAUCI: Yeah, I mean, obviously, as we get further and further in the experience with Omicron - and perhaps even variants that might come after that - it's very, very clear: For example, with Omicron, if you have a larger number of infections - and as the data that I presented here indicate that there is - it looks like a significant lessening of severity compared to others - it becomes much more relevant as to what the seriousness of the impact on society is.
We're never going to stop counting tests. But we're looking forward, as I think everyone feels is appropriate, that, ultimately, when we're going to have to, quote, "live" with something that will not be eradicated and very likely would not be eliminated, but can actually be at such a lower level of control - namely a control that does not disrupt society, does not disrupt the economy - that it will be much more relevant as to what the level of seriousness of impact is, as opposed to infection, which might turn out to be milder.
So we very well may see a transition in that direction as the months go by.
MODERATOR: Next question. Let's go to Cheyenne Haslett at ABC News.
Q Hi, thank you for taking my question. Can you guys hear me all right?
MR. ZIENTS: Yes.
Q Okay. Great. I wonder - the FDA put out a confusing statement about rapid tests last night, and I was hoping to get some clarity. The statement they're less sensitive detecting Omicron but they still work. Can you clarify at exactly what phase people can actually trust rapid tests when they should be using them? And can you give an accurate number - or can you give a number for how accurate they are up against Omicron?
And lastly, Jeff, if you have new numbers on what percentage of eligible people are boosted - I think you gave some two weeks ago - that would be helpful. Thank you.
MR. ZIENTS: Good. So, I'll go first on the FDA test. And then, Dr. Fauci, if you want to add anything.
You know, the FDA clearly recommends the use of authorized at-home tests. They are a critical tool in our efforts to stop the spread of COVID-19, as Dr. Walensky expanded on earlier with her guidance.
And yesterday's release from the FDA was to keep the public aware of their ongoing work to evaluate the FDA-authorized test level of sensitivity, specifically to Omicron. But it's clear that they are recommending their continued use.
As has been known for a while and it was stated in their release, PCR tests are more sensitive than antigen tests, but I want to again emphasize that both are critical tools to stop the spread of COVID-19.
Dr. Fauci, anything to - or, Dr. Walensky, anything to add or subtract there?
DR. FAUCI: Well, I think you said it very well, Jeff. When you're dealing with an antigen test, everyone knows from the beginning that it is not, by the nature of the technical aspect of the test, as sensitive as a PCR. So it isn't 100 percent sensitive and not like a PCR. But it has a considerable degree of usefulness in a number of different circumstances, some of which Dr. Walensky has already mentioned in her remarks.
What the FDA was saying: that when they were looking at the sensitivity with regard to Omicron, in some of the tests, there appears to be somewhat of a diminution, not a disappearance, but a diminution of the sensitivity.
The fact that the sensitivity is diminished somewhat does not obviate the importance of the still advantage and usefulness of these tests under different circumstances. That was the message of the FDA. They wanted to make sure they were totally transparent in saying the sensitivity might come down a bit, but they did emphasize there still is an important use of these tests.
DR. WALENSKY: And, Jeff, if I might add to that: Another important use is where we use them for serial testing in places like "test to stay" to keep children in school, in higher ed to keep our college campuses safe. So, lots of important uses in addition to the one I outlined. And if you're using them serially, you are able to easily give up a little bit in terms of sensitivity.
MR. ZIENTS: On your question on boosting: I think, importantly, we're continuing to boost about a million people a day, which is a good pace. Obviously, the more people who get boosted, the more people who get the highest level of protection.
The data I do have off the top my head is we're nearing two out of three seniors, those 65 and older, who - those who are most vulnerable - of the eligible seniors, about two out of three are now boosted.
And I'll follow up or Kevin will follow up and get you the overall percent of those eligible, what percent have now received booster shots.
MODERATOR: All right, next question. Let's go to Joel Achenbach at Washington Post.
Joel?
MR. ZIENTS: Kevin, we're not hearing anything on this end.
MODERATOR: Yes, let's go ahead and go to Jeremy Diamond, CNN.
Q Hey there. Thank for doing this briefing. On the 500 million tests, can you outline specific progress that you've made in getting those 500 million antigen tests rolled out next month? Do you have a launch date for the website and for the arrival of those first shipments? And is there anything that you're doing to ramp up PCR capacity as well?
And then secondly, to Dr. Walensky on the quarantine guidance: You know, this is the first time that we've seen you distinguish between people who are unvaccinated and those who are fully vaccinated, eligible for a booster, but have not gotten it yet. So, should those people who are more than six months from their second mRNA dose or two months from J&J no longer consider themselves to be fully vaccinated? Thanks.
MR. ZIENTS: So, on testing and the half billion tests bought by the U.S. government to be distributed for free: The Department of Defense and HHS are executing on an accelerated contracting timeline. Companies are already submitting information, and we expect the contract to be completed late next week.
That means that the first deliveries for manufacturers will start January. We'll set up a free and easy system, including a new website to get these tests out to Americans. We're actively working to finalize that distribution mechanism, which includes a website where people will be able to order tests for free. And we'll share more details in the weeks ahead - days and weeks ahead.
We're able to do this now because of all the steps we've taken to increase testing supply and manufacturing capacity.
We have also taken steps on the PCR front, to answer your question there. You know, there are tests available at many websites and local pharmacies.
Obviously, demand is stronger; in certain areas, even higher. And in those areas, we're supplementing, as you know, with federally run testing sites that we've set up in New York City. As I mentioned, we're doing the same in Philadelphia, New Jersey, and Washington, D.C. And we're continuing to work with states to add those federally run testing sites where needed.
But tests are available online and in many local pharmacies - the rapid at-home tests.
Over to you Dr. Walensky.
DR. WALENSKY: Yeah, thank you, Jeff. And thank you, Jeremy, for that question.
So, our CDC guidance has been very clear that people should get their boost when they are eligible. That is both for - because of waning immunity and because we need more protection against Omicron.
With regard to your question specifically about people who have received two doses of their mRNA or perhaps just one dose of a J&J vaccine who are eligible for a boost but haven't yet gotten it: We do know that they do have some protection against severe disease and death but that they do have quite a bit of waning with regard to protection against infection. And since these are guidelines for quarantine, we really wanted to have those measures in place since they have had quite a bit of waning protection against infection.
MR. ZIENTS: Next question.
MODERTOR: All right. We have time for a few more questions. Let's go to Asma Khalid at NPR.
Q Hi there. Thank you, guys, for doing this. Two quick questions. Dr. Fauci, I know that you have said that you don't think people should expect any requirement in domestic flight travels - any domestic travel mandate. There have been, I'm sure as you all know, a number of public health experts who have been suggesting that would be a good move. So, could you explain the science in saying you do not think that should be on the table anytime soon?
And then, for Dr. Walensky, I know you were on CNN this morning speaking to sort of risk tolerance around the changing quarantine guidelines and the idea that behaviorally, also, folks who were not necessarily going to be, under mild symptom - mild symptoms - I'm sorry - willing to quarantine for up to 10 days. Can you expound on that for me a little bit?
You know, I know that there's been some pushback from people thinking that there are other guidelines that have been difficult for people to tolerate - you know, kind of case in point is the mother of a toddler keeping a mask on a toddler is one that I think many parents of young children would say is very difficult from a behavioral science perspective as well.
DR. FAUCI: So, with regard to the issue of traveling, let me make sure we continue to clarify what I've been trying to do: I had said, and I'll say it again, that we - when we talk about keeping America safe and keeping our citizens safe, everything that is an intervention is always on the table and always discussed. And we discuss it regularly on - literally on a daily and a weekly basis.
The difference between requiring a vaccination before you get on a plane to come from out of the country into the United States is for the obvious reason of keeping infection, particularly new variants, out of the country.
When you're dealing with domestic flights, you want to keep people safe on domestic flights. And as I said, right now, we feel that the masking requirement and the degree of filtration on a plane is sufficient to keep people safe.
However, as is very clearly the case for domestic travelers, as I mentioned, we want to keep them safe, but we believe that the requirement achieves that goal. If there's a need to do more beyond this masking, mainly having a vaccine issue, we will seriously consider that as new information arises.
So, it's just keeping an open mind that the situation may change. But at this particular time, we do not feel that is necessary to make that a requirement for domestic flights.
MR. ZIENTS: Dr. Walensky?
DR. WALENSKY: Yeah, thank you, Jeff. Asma, thanks for this question. I think you're referring to my discussion with regard to isolation rather than quarantine. And what we really do know is that the vast majority of your transmissible time is in those first five days. Up to 85, 90 percent of all of your transmission is happening in those first five days - those two days before you have symptoms and the two to three days after. So, we think it's most important to make sure that people are isolating during that period of time. And then any of that lingering small amount of transmission afterwards would be prevented by masking.
MR. ZIENTS: Just one follow-up from a previous question on boosters; I did track down the data. So, as I said, nearly two out of three eligible seniors, those ages 65 and older, have now been boosted. And for 18 and over - so, the population 18 and over - 45 percent - about 45 percent have now received a booster, of the eligible.
But, you know, those numbers have gone up a lot - doing about a million a day. But as the doctors continually emphasize: Everybody who is eligible should go get boosted as soon as possible.
MODERATOR: Next question. All right, we're going to do two more questions.
Nate Weixel, The Hill.
Q Hi, thanks. Just a question on the isolation and quarantine guidance. Why was there no distinction between vaccinated and unvaccinated with regards to the five days? I mean, is there evidence that the virus is going to be less contagious after five days no matter what your vaccination status is?
MR. ZIENTS: Dr. Walensky.
DR. WALENSKY: Yeah, thank you for that question, Nate. The - you know, obviously, vaccination and boosting is going to prevent you from getting virus to begin with. But if you happen to be one of those breakthrough infections, we have seen data that you - at least for other variants - that you peak at around the same place, if you happen to be a breakthrough, than you were - than you would if you were unvaccinated.
You may have a slightly steeper rate of decline than if you were unvaccinated. But, in fact, most of that is still happening in the first five days, and therefore we didn't feel like we had enough granularity to distinguish between the two.
Next question.
MODERATOR: Last question. Let's go to Evan Lambert at NewsNation Now.
Q Thanks for taking my questions. I have two. So, I'm still a little bit unclear on why isolation guidelines don't include suggesting a negative antigen test. If people can get one, why shouldn't they check to make sure they aren't infectious before they leave isolation?
And then the second one, I guess, maybe for Dr. Fauci. Can we get a clear recommendation: Should Americans cancel their New Year's Eve plans? Thank you.
MR. ZIENTS: Dr. Walensky.
DR. WALENSKY: Yeah, so, we do know that certainly a PCR - you can stay positive in your PCR for a long period of time.
But with regard to the question of your antigen is: We do not know how well those antigen tests perform at day five in detecting transmissibility. And it is for that reason that we would say, even if you had a negative test, we would want you to mask, and even if you had a positive test, we would also want you to mask. And therefore, given that these antigen tests are not authorized for use in this way, we did not recommend them at that time.
MR. ZIENTS: Dr. Fauci - New Year's Eve.
DR. FAUCI: Yes, thank you very much for that question. So, similar to what I said for the Christmas holiday, it goes true here. If you are in a situation with a family setting in your home with family, parents, children, grandparents, and everyone is vaccinated and boosted, although the risk is never zero in anything, the risk is low enough that we feel you should continue to go through with those plans of having a home-related, vaccinated, boosted gathering with family and close friends who are also vaccinated and boosted.
So, it really depends on what your plans are. You said, "Should you change or cancel your plans?" If your plans are to go to a 40- or 50-person New Year's Eve party with all the bells and whistles and everybody hugging and kissing and wishing each other a Happy New Year, I would strongly recommend that this year we do not do that.
MR. ZIENTS: Thank you, everybody. Thanks for joining. I wish everybody a safe and happy New Year, and we'll look forward to next week's return to our normal-style briefings. Thank you.
11:52 A.M. EST