The CDC's Revised Face Mask Advice Is Based on Information That Was Available Months Ago

Surgeon General Jerome Adams wants us to believe the CDC realized the danger posed by asymptomatic carriers only last week.


The Centers for Disease Control and Prevention (CDC) revised its advice concerning face masks and COVID-19 last week, telling us to "cover your mouth and nose with a cloth face cover when around others." The CDC had previously said that "if you are NOT sick, you do not need to wear a facemask unless you are caring for someone who is sick (and they are not able to wear a facemask)."

The official justification for this shift is that the CDC suddenly realized people can transmit the COVID-19 virus even when they do not feel sick. Yet that is something we have known for months.

"Here's what's changed," Surgeon General Jerome Adams claimed on Meet the Press yesterday. "We now know that about 25%, in some studies even more, of COVID-19 is transmitted when you are asymptomatic or presymptomatic." While that particular estimate, which CDC Director Robert Redfield began floating on March 31, is relatively new, it has been clear at least since February that people can carry the virus for days before they develop symptoms and that some carriers never feel ill.

A study published in February, based on 88 cases in Wuhan, China, estimated that the mean incubation period for COVID-19 was 6.4 days. Another study published the same month, based on "publicly available event-date data from the ongoing epidemic," put the incubation period at two to 14 days with a mean of about five days. Based on those findings, the researchers recommended that "the length of quarantine should be at least 14 days." A March 10 study, based on 181 cases, essentially confirmed those results, estimating a mean incubation period of five days and finding that "97.5% of those who develop symptoms will do so within 11.5 days."

A January 30 letter to The New England Journal of Medicine, based on several cases in Germany, warned that "asymptomatic persons are potential sources of [COVID-19] infection." A February 13 letter to the International Journal of Infectious Diseases estimated that 31 percent of people infected by the COVID-19 virus do not have symptoms. A research letter published in The Journal of the American Medical Association on February 21 described an asymptomatic carrier from Wuhan who seemed to have infected four other people. A February 26 Global Biosecurity report noted that "asymptomatic transmission has been documented" and "the viral load in symptomatic and asymptomatic people is not significantly different."

A report from the World Health Organization published around the same time nevertheless depicted asymptomatic infection as rare. While "asymptomatic infection
has been reported," it said, "the majority of the relatively rare cases who are asymptomatic on the date of identification/report went on to develop disease."

When it comes to wearing face masks in public to protect others from infection, however, it does not really matter whether carriers are asymptomatic or presymptomatic. The point is that people can transmit the virus without realizing they are carriers. Given the incubation period, that phenomenon must be common.

A March 4 study of 24 asymptomatic COVID-19 patients in Nanjing, China, found that five subsequently developed symptoms such as fever, cough, and fatigue. "None of the 24 cases developed severe COVID-19 pneumonia or died," although 17 had CT scans consistent with the disease. The remaining seven, who were younger than the rest, "showed normal CT image and had no symptoms during hospitalization." A March 12 study of passengers and crew on the Diamond Princess cruise ship estimated that 18 percent were asymptomatic.

More-recent testing of the general population in Iceland found that about half of the volunteers who tested positive reported no symptoms. Some of those people may subsequently have developed symptoms. They were nevertheless unwitting sources of infection during the period when they had no reason to suspect they were carriers.

During a White House briefing yesterday, a reporter asked Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, "how many asymptomatic cases" there might be in the United States. "We don't know," Fauci replied. "Even among us…we differ about that. It is somewhere between 25 percent and 50 percent." He cautioned that "right now we are just guessing," saying the issue would be clarified by wide antibody testing, which will identify people who had the virus and recovered, many of whom may never have realized they were infected.

"Seriously people—STOP BUYING MASKS!" Adams tweeted on February 29. "They are NOT effective in preventing [the] general public from catching #Coronavirus, but if healthcare providers can't get them to care for sick patients, it puts them and our communities at risk!"

By that point, it was clear that transmission by asymptomatic or presymptomatic carriers was playing an important role in the pandemic. Now Adams wants us to believe no one knew that until last week. The misguided advice from Adams and the CDC needlessly endangered people who could have benefited from the precautions they are belatedly recommending.

NEXT: Sotomayor Upbraids SCOTUS for a Decision That ‘Destroys Fourth Amendment Jurisprudence That Requires Individualized Suspicion’

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  1. I’m not wearing a face mask.
    I’m not staying in my home.
    I’m going wherever and whenever I would like to go and invited.
    I’m telling the government to fuck off.
    I’m telling everyone that will listen about the facts of this minor cold

    1. Rebel without a clue.

      1. I am slowly training myself to tune him out like I did for some other pests around here, since we don’t have the option of blocking people.

        1. That is why they added the little dashed vertical lines down from the original post. As soon as you read the poster’s tag, you know if you should just follow the line to the next real post, or read on and see if there is actually a thoughtful reply.

    2. How do you explain people dying of a minor cold? How do you explain hospitals filling up with people with minor colds?

      I have a personal friend who caught it. He’s doing fine and will pull through because he is young, but the hospital turned him away because it’s full. He is recuperating at home in bed. I have never in my life been bedridden due to a “minor cold”, not been at risk of pneumonia.

      Even your hero Trump realizes this is a big dangerous deal, why can’t you?

      1. Which hospital is this? Every hospital I have been watching save for a couple in New York has been reporting LOWER than normal occupancy, because they have been working to get people out of the beds over the last weeks.

      2. Which hospital? Lots of hospitals in rural areas are hurting for normal patients to keep the money rolling in.

        Empty beds abound.

        This cough due to cold is such a variance from normal emergency medical needs from disease, like the seasonal Flu/Cold.

        1. Florida is reporting to be at 50% capacity for hospital beds, so… agreed – empty beds abound.

          1. It’s more likely they simply told him to go home because he would be fine, and never “turned him away”.

    3. poor unreason chickenshits. Huddled in their apartments rocking themselves to sleep.

      1. I agree with your spirit, if not the specifics of your reasoning. My personal thinking is that the overall harm done to the economy in the form of lost jobs and income for those at the lower end, and the middle, of the economic spectrum is just as bad as the harm done by the transmission of the disease from person to person.

        It would be far better to simply ask everyone to do a little social distancing and wear a mask if they’ve been exposed. Naturally, those most at risk (the sick and the elderly) should isolate themselves as much as possible. Other than that, we should go back to work and prevent the drastic losses of income and jobs. As it stands now, we’ll be spending billions on subsidizing joblessness.

        1. This, exactly.

    4. Loveconstitution1789 – I agree with most of your content but this one I gotta say something.

      I got the minor cold covid-19 and recovered after 9 days of random symptoms of which 2 were pretty bad (chest pain, shortness of breath, heart arrhythmia, etc thinking very confidently that I was a goner). March 25th was my first day of no symptoms.

      Since then I have had significant brain fog and occasional heart palpitations. My muscles cramp up after any sort of repetitive movement. Further research is showing that there is a neurological element to a smaller portion of those afflicted.

      Because of my pre-existing conditions (pre-diabetic, smoker, pre-copd, probably pre atherosclerosis) I believe my organs sustained more damage than healthy people. However, my daughter (who gave it to me and my other daughter) now has brain fog and headaches. These are pretty good signs of encephalitis. If it gets worse for either of us we will obviously have to get checked out and possibly admitted, thus, creating a further burden on the hospitals.

      In SoCal where I’m at, the hospitals are not overran yet. So it may very well be no big deal. My parents work in healthcare and are under the impression it won’t hit our area for another 3-4 weeks.

      What I’m saying is, whether or not you get sick isn’t the biggest problem – everyone will. If you have preexisting conditions though, you may want to hold off on the invincibility attitude because the consequences – at least for me at age 40 – are looking permanent. In all likelihood I have guaranteed myself a stroke or thrombosis due to my inactive lifestyle unless I get serious about my health (I won’t).

      Just a heads up man – I’m guessing you are older than me by at least 15 years, so that raises your risk of complications even if you are in perfect health.


  2. The Centers for Disease Control and Prevention (CDC) revised its advice concerning face masks and COVID-19 last week, telling us to “cover your mouth and nose with a cloth face cover when around others.”

    Do we really need the CDC for such common sense advice?

    Also, does this mean Trump was technically correct when he recommended people wear scarves to limit transmission?

    1. The one study there is for cloth masks suggests that they are worse than wearing nothing. Now, I wouldn’t put much trust into just one study like that, but cloth masks probably aren’t very effective. If you can’t find a mask, cut up a HEPA vacuum cleaner bag. Or just cut two holes in it and put it over your head.

      1. It’s not to protect you it’s to keep your saliva from getting over everything.

      2. Here’s a study showing effectiveness of surgical masks being as effective as n95’s at preventing virus infection by the wearer of the mask:

        1. Yep, except even surgical masks are unavailable to the general public. Which further illustrates how stupid all of this is. Gov’t wants us to take precautions, but we can’t buy masks, hand sanitizer, sanitizing wipes, or Lysol disinfectants.

      3. Two holes? What for?

    2. Trump is most technically correct. It’s better than nothing. How effective it is when people still go around touching things then touching their faces is another matter. But their positive effects undoubtedly exceeds the negative effects of false security.

      1. If everyone wears a mask their saliva won’t get on everything.

  3. Anyone know why I can’t get any groceries delivered? There are a lot of people out of work, aren’t there? Why aren’t they getting hired to deliver groceries?

    1. Because they’ve just been released from prison?

      1. Doesn’t stop them from picking up the trash. Most of the trash pick up drivers are ex-cons.

    2. I was actually thinking about that earlier. Grocery stores around here offer a pickup service. Place your order online, pay with plastic, then drive up and get it. I imagine they would be completely overwhelmed, and even if they did hire the staff to keep up it would cost them a lot of money. Grocery stores run on paper-thin margins.

      It would make sense to do pickup or delivery. Keep people from mingling. OTOH if one of the employees was sick then they could pass it along to literally thousands of people.

      1. They stopped the service. Didn’t mention that.

        1. Just charge for the delivery or even pick up. I would gladly pay a fee for the convenience.

          1. You would. So would I. But most people would consider it to be gouging.

    3. Grocery delivery is definitely a thing.
      Look up InstaCart
      Or Google “grocery delivery”
      It’s 2020, c’mon.
      And you can order Walmart online, they gather all your groceries and bring them to your car

      1. Grocery delivery is a thing – but only if you live in the right area.

        Grocery delivery is pretty available for inner ring suburbs but harder to get in the exurbs. Grocery delivery in urban areas is decidedly mixed. No problems if you live in the gentrified condos but good luck getting a delivery to the projects. Grocery delivery to most rural areas, on the other hand, is beyond the pale. There’s just no way to make deliveries at that distance cost-effective.

    4. I certainly hope that we see a shift from “everybody stay home” to “elderly and the immunocompromised stay home, and call this toll-free number for free assistance with arranging free, no-contact delivery of your food, medicine, and toilet paper.”

      I’ve never had my groceries delivered to my door, but I know that a lot of major supermarket chains offer it. I would assume there’s a surcharge, but I have no problem with using tax dollars to cover the cost of delivery for fixed-income people.

    5. Chipper – here in SoCal I logon to Walmart grocery at midnight and it’s first come first serve for delivery for the next two days. I’ve gone to vons website at numerous times throughout the day and night and have not been able to find an opening for weeks now. They suck. Target is 10 bucks a month and they are always available for grocery deliver but their availability is hit or miss – sometimes you get substituted stuff you don’t like. Good luck!

  4. “Seriously people—STOP BUYING MASKS!” Adams tweeted on February 29. “They are NOT effective in preventing [the] general public from catching #Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk!”

    This should go down in the Stupid Tweets Hall of Fame. Why anyone would take anything this moron says from here on out seriously is beyond me.

    1. He’s a Trump appointee. By definition he cannot be a moron. QED.

      1. He’s a Government appointee — thus, by definition, he cannot be a moron. FIFY.

    2. For what it’s worth, last week the WHO were still saying that the cheap and DIY face masks weren’t effective at stopping the transmission.

      So many people I see out wearing the masks are constantly fidgeting with them or touching things and then touching their faces, I imagine they aren’t doing much but trapping their coughs/sneezes.

      And if some studies are to be believed, more than 60% of healthcare workers don’t remove their masks properly, increasing the likelihood of transmission.

      All of that is to say, I’m not really sure as to their efficacy for the everyday person.

  5. The postmortem on this whole debacle shall be interesting (if we ever see one we can trust).

    1. I ain’t digging up the infected bodies from the park.

  6. Wait two weeks. By then, they’ll be telling us that masks cause COVID-19.

    1. Technically they do if you don’t properly dispose of them after wearing them.

  7. Well, we do know that the numbers from China are bullshit.
    We do know that the WHO is bullshit.
    We do know that so far, all the models have been wrong, often by an order of magnitude.
    We do know that almost all of the policy decisions are based on the above, or on other shit derived from the above.
    So all we really know is that whatever Trump has done or will do is wrong, because he is not her.

    1. +1000

  8. The masks are largely pointless. I see everyone wearing one now, and 90% of them are wearing them wrong, or they take them off momentarily or slide them to the side, etc., when they become inconvenient.

    The virus sticks to clothing, surfaces, hands, and many other things. There are so many possible points of entry (eyes, hair, for example) that a mask alone is hardly mitigating anybody’s risk, if at all.

    Pandemic theater, at its finest.

    1. Like they said in the article, the masks aren’t for healthy people. They don’t prevent you from catching the disease. They are for sick people. They keep sick people from coughing and sneezing germ-laden spittle into the air. They catch the nasties before they get into the air. But they don’t do dick to prevent a healthy person from catching it.

      1. Even for the sick, the masks are largely pointless at stopping the spread. You don’t have to cough in someone’s face to infect them. An infected person sheds the virus in any number of ways (clothing, hands, hair, etc.). They walk into a grocery store, touch something (or, walk by it) and then somebody else touches that same things, and on and on it goes. The virus lives on cardboards and plastics for days, and grocery stores are full of cardboards and plastics.

        There’s no way to even really measure, in a real environment, the effect of wearing a mask, even for the sick.

      2. Masks do reduce the risk of you catching an airborne virus. Multiple studies have proven that.

    2. People – the virus load (amount of virus particles present when you are infected) will determine your severity. That’s why doctors and front liners are dying.

      Yes, virus on money isn’t likely to infect you, and even less likely to infect people after you. What got me was the sustained exposure to my sick daughter (who only had a bad stuffy runny nose and a very slight temp). No clue how she got it but she and her mom and step dad went to fucking Lake Tahoe right before they closed the schools – they closed during that weekend. Idiots, but whatever. They stayed in a big cabin with probably 16 other people. Now you understand why my ex and I never saw eye to eye. She’s a fucking sheep but that’s neither here nor there, I wish her no ill will. She had to have got it so asymptomatic cases are definitely a thing too.

      The masks work dude, just look at the lower cases in countries that use them. It is a good safeguard while you’re in public, but you’re right that they won’t do shit if you’re constantly around someone who is infected unless you’re flawless in your use of them. Since it’s obvious that even doctors are still getting this, it’s likely you won’t be flawless in your use.

      So, do the rest of the public who you shouldn’t be out mingling with a favor by minimizing your virus shedding on everything. Just in case. We are locked down anyways, might as well do this one thing right until we can’t take any more. I’ve got maybe two weeks before I begin actively protesting in public. This shit has got to give.

      1. Governor in my state just extended stay at home to May 1. In spite of the fact that we only have 12 people dead over the course of 4 weeks. I suspect most other states’ governors will do the same.

        We’re all going to go out in public and protest. And it won’t do a damn bit of good.

  9. From what I understood, they said the masks were not effective because they did not want a run on masks by the general public when they thought theere might be a shortage for medical professionals. They put out misleading info specifically to manipulate the public’s behavior. That has a boy who cried wolf danger to it as it breaks down public trust if used too often.

    1. A “noble” lie.

    2. And that’s why no one trusts the government. Am I the only one who remembers the seasonal flu vaccine shortage several years ago? There were all kinds of public service announcements telling us that only children and old people needed the vaccine. The rest of us should just skip it.

      The next year, there was plenty of vaccine and all the PSRs said EVERYONE needs a flu vaccine.

      One of those years was a blatant lie. If the second year is true, then the first year should have said “We want to vaccinate everyone, every year. However, we’re short this year so we’re asking lower risk groups to skip vaccination and leave the supply for higher risk groups.”

      Sure, some selfish people would ignore the request, but at least it would have been honest. Instead they lied to us and showed that we can’t trust anything (health, economic, etc.) that the government tells us.

      Damn, I miss the old days when I was ignorant and believed that the government was “by the people, for the people”. I wish there really was a blue pill.

    3. And the irony is that if they had said “We are concerned that we don’t have enough masks for our emergency personnel, so if you have extra masks, please contact your local hospital and donate what you can”, not only would they have not discredited themselves, hospitals would likely have more masks than they would know what to do with!

      Not only do they think they can manipulate the Public by lying to them, but they underestimate the generosity of the American people when they do this.

    4. They particularly didn’t want the general public snatching up the medical-grade N95 masks. The new recommendation specifically endorsed cloth masks — the sewing of which has become the latest arts-and-crafts trend. (I’ve seen several different patterns and instructions shared on Facebook.)

      Are they as effective as N95 masks? — Definitely not, unless you’re talking about Chinese-made N95 masks…)

      Do they work? — Statistically, it’s almost certain that they reduce transmission risk to some degree, simply by trapping blobs of spit and snot.

      Can they make things WORSE? Well, if you wear one for two weeks straight without laundering it, then virus-laden snot will build up in the fabric and get all over your fingers every time you put the mask on. Ideally, you should have two or three cloth masks so that you always have a clean one available while the others are being washed.

    5. That’s exactly the way I read it. “Stop buying up all the masks!”

  10. Honestly, why should we give a fuck about this? The models that they’ve been using were completely wrong about the infection rates and hospital resource needs, predictions that were made for previous days have been revised after the fact by up to 75%, and previous estimates memory-holed to disguise it.

    THAT’S a bigger scandal than this stupid non-issue about advice on when to wear a face mask.

    1. Amen.

      Now if someone could please explain why there’s a floating navy hospital moored in NYC that isn’t doing squat because as it turns out, there more than enough beds for COVID-19 patients AND everyone else, despite the apocalyptic predications of our tireless, purportedly well-meaning panic merchants.

      Panic has turned out to be anything but an “overabundance of caution” but a gross misallocation of resources.

      1. Did you really expect anything else from central planning?

    2. Really, the only reason we should be worried about this is that Government institutions that are supposed to be protecting us are lying to us. When the truth comes out, it burns their credibility. When something truly dangerous comes down the pike, and they actually have a good thing for us to do to prevent us from dying, we won’t listen, because they won’t have any credibility left.

      If they had been truly honest — saying things like “Hey, stop buying masks: we need them for medical professionals!” — or “Hey, our old models were pretty bad; we have updated ones, and here’s what we should do based on those” — along with apologies like “sorry for the previous advice — this has been a learning experience for all of us! We’re all in this together!” and the public would likely do anything that such an agency requested, or at least take it very seriously.

      I don’t know what would be worse, though: an agency that is completely ignored even when they are right because they have shown us they are cynical, lying bastards, or an agency that’s blindly followed because they have shown themselves to be honest, willing to trust the People to do the right thing, and sincerely trying to find the best way out of a horrible situation, but who might abuse that trust later, when a cynical, lying bastard becomes the head of that organization …..

      1. There are countries that I would probably trust what the government said is best to do – you know, any of those nordic countries . And I don’t think that’s a bad thing.
        Over here, we have distrust going both ways – the gov can trust our greedy asses to be fair or care about anyone else, which in turn means we can’t trust a word they say. That’s capitalism for ya. I have no solution for that and don’t know anyone who does.

        1. Capitalism has nothing to do with it. Indeed, Americans have proven to be very generous, and very trustworthy, if the situation warrants it.

          And there are plenty of non-Capitalist countries that have a proven inability to trust their own citizens — we are in this mess in no small part because China did everything in its power to squash news about this virus.

  11. Not really sure why this is relevant.

    AFAIK, masks are in short supply, even for medical workers. The chances that Joe Sixpack will be able to buy one is minuscule. And since I would expect they are one use only, the chances anyone would have enough are even smaller.

    I don’t think that a bandanna will help all that much. So I don’t think there are a lot of good options other than staying home.

    Seems like they gave the guidance to keep people from buying out all the masks in the first place. Once you can’t get them they tell you it’s ok. Souds like government.

  12. No kidding. I assumed we all knew the CDC was lying the past two months, and we were letting it slide since we knew why they were lying. It was only when I saw people suddenly wearing masks this weekend that I realized that people actually believe what the federal government tells them, which is….bizarre.

  13. The mask testing reports are pretty iffy. A feel good recommendation at best. People will fiddle with anything on their face so may be detrimental overall.

    I note that the media at the daily press conferences are not wearing masks. Must be anti-science and won’t follow government guidelines.

  14. love how the hospital ships were sent to show they weren’t needed

    1. They’re making a big show out of moving the COVID patients to the ship now, which was previously used for non-COVID patients.

      Should have isolated the COVID patients in there from the beginning.

      The propaganda is getting increasingly desperate. The media is going out of their way to find outliers of people getting severely sick, despite the fact that it’s mostly the elderly, fatties, and fat elderlies dying from this, especially nursing home residents. The CBS Evening News had some sob story from a nurse, talking about how “exhausted” she was after working a 12-hour shift–something that is perfectly common at hospitals even in normal times. Oh, and apparently Cuomo is going to allow the morgues to be emptied after stupidly forbidding people from burying their own relatives.

      1. Can you give me a link for that Cuomo/morgue business? I couldn’t find it again when I went looking today. Was it that he shut down funeral homes?

      2. JFC, if I have to watch one more crying crybaby cry about how haaaaarrrrrd their job is . . . Suck it up, buttercup, what did you think you were signing up for when you became a doctor or nurse?

  15. After 20 years of the threat of biological terrorism the government has proven itself woefully unprepared. They’ve failed AGAIN.

  16. “They are NOT effective in preventing [the] general public from catching #Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk!”

  17. Should be looking for ways to get the virus eradicated and treat those already exposed

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  19. “The official justification for this shift is that the CDC suddenly realized people can transmit the COVID-19 virus even when they do not feel sick. Yet that is something we have known for months.”

    Which will end up being Trump’s fault, no doubt.

    1. A January 30 letter to The New England Journal of Medicine, based on several cases in Germany, warned that “asymptomatic persons are potential sources of [COVID-19] infection.”


      The first case of COVID-19 in Germany was reported 70 days ago on 1/26/2020. — Johns Hopkins coronavirus website

      That January 30 letter was apparently based on that first case of COVID-19 in Germany — and the letter was augmented on February 6. One case — and you think the CDC should have acted on it? You’d be the first one to criticize if mask wearing turned out to be pointless.

  20. The reason they didn’t recommend it is simple: the CDC didn’t want people go out panic-buying N95 face masks and they didn’t want people to feel a false sense of security in lieu of isolating. Typical CDC arrogance. There is a reason Trump wants to shut down lots of federal agencies, if only Congress would let him.
    Now they recommend you make simple cloth masks. To the degree that they do anything, they mainly prevent you coughing on someone else and touching your face.

  21. Cloth and surgical masks are essentially useless at filtering SARS-CoV-2: Only N95 masks work and we don’t have enough of those for all medical personnel, much less the general public. The CDC has changed its guidelines simply as a P.R. move to make it look like they’re trying something new, not because it will be in any way effective. The best way to handle this outbreak is the same advice the Surgeon General provided weeks ago: wash your hands regularly, only go out when you absolutely have to, and keep as far away from other people as possible.

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