University of Florida researchers find no asymptomatic or presymptomatic spread

UF Dept of Biostatistics, 2004 Mowry Rd, Gainesville, FL


Four researchers from the University of Florida Department of Biostatistics co-authored a study published online by the Journal of the American Medical Association. They performed a meta-analysis of 54 studies looking at the household secondary attack rate of SARS-CoV-2. According to the CDC, the secondary attack rate is the number of new cases among contacts divided by the total number of contacts.

The researchers confirmed that SARS-CoV-2 is more contagious than other coronaviruses, with a secondary attack rate of 16.6% (95% CI 14.0%-19.3%) compared to 7.5% (95%CI 4.8%-10.7%) for SARS-CoV and 4.7% (95%CI, 0.9%-10.7%) for MERS-CoV.

Their findings also confirmed the attack rate is higher to adult contacts compared to child contacts and to spouses compared to other family members.

The secondary attack rate for symptomatic index cases was 18.0% (95% CI 14.2%-22.1%), and the rate of asymptomatic and presymptomatic index cases was 0.7% (95% CI 0%-4.9%), “although there were few studies in the latter group.” The asymptomatic/presymptomatic secondary attack rate is not statistically different from zero, and the confidence interval is technically 0.7 ± 4.2, resulting in a range of -3.5%-4.9%, but attack rates cannot be negative, so it is truncated at 0.

  • Amazing how Covid 19 cannot be found in a blood test? Scientists and immunotherapy experts agree…NO SUCH THING AS CV19V2! Also amazing the Common Flu was all but Non Existent
    In 2020! Get it?

    • The flu was almost non-existent due to social distancing, masks and hand washing. That and people not being able to send their sick kids to school while going to work sick as well. It’s really not a conspiracy mystery.

          • ICU and Critical Care professional here. Sorry to jump in on this, but after 20 years in the business I can tell you COVID-19 is real. Please tell me what is making all my patients jamming the ICU sick? If all this is a tinfoil-hat conspiracy, why is every room occupied with a patient on a ventilator? Sure there is corruption and exploitation of the situation! Politicians like “never let a crisis go to waste” Rahm Immanuel will use this to their benefit, but we’re dealing with too many viral pneumonia cases for this to be utterly made up. Bedside clinicians like me would have to be in on the fix as well, and we’re as ready to be done with this thing as anyone!

          • To Mr Vinalaski, a hospital full of “covid” patients doesn’t prove causation but we can’t rule it out. The fact that the eugenicists knew this was coming and had the outrageous, draconian script ready to activate is something that anyone with common sense would want independently investigated.

          • Bob Vinalaski
            PLEASE, Start doing a study whether each patient had received a flu shot previous to being in the hospital. Also, facts about the shot, such as when and how many, and how often. Also, any other vaccines in the previous 5 years, which ones etc. I really believe there is a link.
            In my own personal analysis, which is not anything formal, it shows that people who HAVE had a flu shot are exceptional indicators to showing positive for this virus.
            Every doctor, nurse, and health professional that has access to study this should do it now.

          • “Bob Vinalaski”
            I don’t think the argument is that COVID-19 is not real. The argument is that the number of deaths from COVID-19, while high, is inflated.

        • Viral interference is a thing. It would behoove you to read something other than Facebook./

      • Wow, you’re brilliant! If the flu and Covid are both respiratory illnesses that are transmitted the same way, then why haven’t social distancing, masks, and hand washing stopped Covid? There is logic to your comment. Sorry, just highlighting the obvious.

        • Because subnets dont stop herrings. Just to highlight obvious fish-facts.

          • Most of the people commenting here got their medical degrees from toys r us and have probably never used a google to it’s full potential.

        • Probably because they infect people in two different ways .. one by receptors. The other through host cells

      • If they wore masks, distanced and washed hands and flu went down, how did C19 GO UP? That’s not even logical..

        • Here is a CDC review of over a dozen studies, examining the effectiveness of face masks, hand hygiene, respiratory etiquette and surface cleaning. The study could find no confirmation that masks either protect the wearer from respiratory viral infection nor, if the wearer were infected, that they protected those around the wearer. These were all randomized, controlled trials. And they also found limited effectiveness of hand-washing and surface cleaning. It should be obvious that social distancing works (people in separate rooms cannot infect one another) but that raises the question of whether the 6′ distance is sufficient to prevent transmission.

      • But I thought COVID was running rampant because of laces were enforcing mask mandates and social distancing??? Funny that the flu has disappeared for the same reasons COVID is increasing. Sorry, you can’t have it both ways…that’s not a conspiracy.

      • So we socially distanced, wore masks, and didn’t send kids to school to keep flu numbers down yet Covid-19 numbers still continued to rise. Weren’t we told that those same measures work for Covid-19? Do you see the flaw in your reasoning? You can’t say those measures worked for flu and then not for Covid-19 because that is precisely what you are implying. Nor can you say people crowded together, didn’t wear masks nor wash hands and sent their kids to school thus Covid-19 numbers rose. You can’t say that people behaved differently for flu than Covid-19. Either they wore masks, distanced and washed hands or they didn’t. Someone’s cooking the books. This article proves that we have been lied to from the start. There never was an asymptomatic spreader. Viruses are obligate parasites. They cannot live outside of a host cell. The idea that a person could be perfectly healthy and harbor this virus in the respiratory tract without getting sick himself defies the basic tenets of virology.

        • the idea that you could harbor the virus but not be sick is called IMMUNITY!
          Which was canceled pre-vaccine!
          That’s what this article is about.
          That we have been told over and over that if you have the virus you are sick even if you aren’t.
          In other words they are lying to make billions!
          And causing excess death in the process.

          • That’s not how viruses work. If you have the virus, you have symptoms. Period. If you’re immune, your body fights and wins nearly immediately killing the virus and making it impossible to spread. You can’t spread a dead virus. Why don’t people that are immune to polio spread it to those that don’t have the vaccine? Because it’s rare in a first world country where nearly everyone is vaccinated therefore making it very unlikely that you come into contact with someone that has it without the vaccine.

          • “If you have the virus, you have symptoms. Period.”

            You really shouldn’t speak on the topic if you’re that ignorant on it as you’ll spread misinformation. You could have HIV (just to pick one) for many years before developing symptoms–in fact, that’s how HIV usually works–or you could never develop symptoms and be an “asymptomatic carrier,” meaning you can pass it on without ever getting sick yourself. https://www.scientificamerican.com/article/hiv-aids-controllers/ A lot of viruses work this way. We knew this many decades ago, How you can not know it today is beyond me. And yes, you can have polio and spread it and never have symptoms. They call that “sub clinical polio.” But it works the same way: asymptomatic spread.

        • Want to know why mask wearing, etc. have stopped flu in its tracks, but haven’t stopped COVID-19?

          Simple. Two reasons:

          1. Each person with coronavirus spreads the virus to (on average) about 2.3 new people. Each person with flu spreads it to (on average) about 1.3 new people.

          Suppose that someone invents a mask that cuts that spread exactly in half. With that mask on, you would spread flu to (on average) 0.65 people, so the number of new cases goes down over time, because people get well and are not replaced by as many new sick people each time. But you would still spread coronavirus to 1.15 people, so the number of new coronavirus cases still goes up over time, just more slowly than without the mask.

          And this would be true for *any* mitigation strategy that reduces the spread by more than a factor of 1.3, but less than a factor of 2.3.

          In other words, masks and distancing reduce flu and coronavirus quite a bit. The difference is that influenza’s low rate of contagiousness makes flu a *lot* more susceptible to those sorts of interventions than coronavirus is.

          2. A lot of influenza’s spread comes from foreign travel, bringing back the virus from the southern hemisphere at the end of their winter to cause new cases during the northern hemisphere’s winter. There’s a lot less foreign travel right now, and some parts of the southern hemisphere wore masks and got their coronavirus spread down to almost zero (I’m talking about Australia and New Zealand here), so there’s even less to bring back.

          By contrast, there are enough coronavirus cases in the U.S. and other countries that we don’t need foreign travelers to bring it in. It’s already here en masse.

          Those differences add up.

          • Just to clarify, they did so well at reducing coronavirus that their flu cases (which were even more severely reduced for reason #1) were approximately zero for several months in a row. And that’s why there was even less flu to bring back.

        • Exactly, if these measures were working we’d be seeing a decline. There’s almost 100% compliance in IL but the numbers are still going up. People aren’t thinking for themselves anymore.

      • Ok using that analysis why is cv 19 spreading and not the flew? And how come flu numbers fro previous years are on par with covid in 2020. Analyze the numbers. Math is the only true science.

        • Why is my sisters hospital jammed with sick people and during regular flu seasons it is not?

      • Wow. So it’s one or the other. You can either claim that the reason why there’s no flu viruses being transmitted. If that’s the case and everyone is following there guidelines then, like the flu, there would be no covid cases either. Or few are following guidelines which is causing massive covid cases (like California) and the flu has magically disappeared.

        Can’t have it both ways.

      • If masks and social distancing worked for the flu why haven’t they worked with covid? Although the term, Conspiracy, is questionable, the word, mystery, is not. Critical thinking matters.

      • With that same logic we should see a decrease in positive COVID cases? They are both respiratory viruses.

      • Covidians: “We’re having a light flu season because people are wearing masks and social distancing.”
        Sceptics:: “Then why are there so many new COVID-19 cases?”
        Covidians: “Because not everyone is wearing masks & social distancing.”
        Sceptics: Is it slow learners day today?

      • The same people that told us that flu went away because of social distancing and sanitizing, told us corona virus is out of control because people aren’t social distancing and sanitizing. Nothing weird about that I guess.

      • Sooo what of the soaring Covid spread with the mask mandates and stay home order? 🤦🤦🤦

      • Actually every illness these days is being categorized as COVID. Thus, the drop in flu numbers. Nothing is labeled the flu any more. It is all covid. It’s actually that simple and has nothing to do with conspiracy.

      • Just think of the 10’s of millions of people we let die from flu by not mandating masks, social distancing (made up term), and handwashing for the last 100 years

    • The common flu was virtually non existent because the measures taken to control COVID. There is an anti body blood test for COVID.

      • You know how ridiculous that sounds, right? The flu isn’t a coronavirus. It would make sense if the common cold numbers went down, however.

    • Maybe cause we’re all wearing masks? Hard to catch the flu if you’re not sprayed?!? Lab tech testing covid here. I see too many REAL POSITIVES for it to be staged. May you never get it. May your family never get it. May you study real historical epidemics and get a brain.

      • Barbara….get out of the lab and take a breath. Lots of folks have gotten COVID and survived! I could list 10 people in a minute without having to think about it…one is my 85 yr old mother in law, another friend – age 65, 27 year old ER nurse….my list goes on and on. I always find it humorous, as well as, telling when someone thinks their opinion and what they do for a living makes someone that doesn’t agree with them…..brainless. Such a strong debate technique. Hope you take some time off….sounds like you need it.

      • Its not about whether our not there are real positives for the virus it’s that the measures they’ve mandated to stop are false and don’t work. This is a nano particle and it doesn’t care if you wear a mask it is airborne and.. . knows no boundaries. If people would stand up tp these tyrannical leaders and take off their masks we’d all go back to living ad normal but all you medical mafia people just want to keep drawing out the narrative because their bottom line $$$$ is to keep people in fear because they are too dumb to see the truth staring at them in the face and go do some independent research.

      • But everyone says too many aren’t following guidelines and not wearing masks resulting in covid numbers to skyrocket. So which is it? Everyone is wearing masks keeping flu numbers down or people aren’t wearing them to control covid?

    • Considering unprecedented mask wearing. Unprecedented isolation,hand sanitizer and hand washing. How could the flu spread as other years?

    • What are you smoking? They can take your blood and get the entire genome of the virus you were infected with! You OBVIOUSLY need to do some research other than reading MEMES. Here are 2 different genomes of Sars-Cov-2. Tell me how they are the same and different that the flu! https://link.springer.com/article/10.1007/s00705-020-04695-3 https://www.ncbi.nlm.nih.gov/Structure/SARS-CoV-2.html .. and I threw in the Genome for Influenza A for good measure so you can see they are not the same! BUT if you cannot read this information then how can you make your claims?????? https://www.frontiersin.org/articles/10.3389/fmicb.2018.02748/full

  • Another study was conducted in Wuhan, China, considered SARS-CoV-2 ground zero. As the American Institute of Economic Research (AIER) reports, the researchers’

    conclusion is not that asymptomatic spread is rare or that the science is uncertain. The study revealed something that hardly ever happens in these kinds of studies. There was not one documented case. Forget rare. Forget even Fauci’s previous suggestion that asymptomatic transmission exists but not does [sic] drive the spread. Replace all that with: never. At least not in this study for 10,000,000.

    Watch the Democrats turn on China in this one instance.??

  • I believe it to be a man made virus from China and i think it has been in the U.S. since April /May of 2019. I think we will see several mutations before we are done .It was designed that way!

  • @ Bob vin… the reason there are so many people jamming ICUs is because MSM has them scared to death that they’ve come down with the 2020 version of the Black Plague.

    If those ICUs are full of people at death’s door (as you claim) , what the hell are those tick-tock dancers doing prancing around, making comedy sketches? Are they so unaffected by a pandemic that could wipe out the human race?

  • Why aren’t ICUs using protocols from the FCLLL Alliance and why aren’t more people reading the over 20 studies from all over the world showing Ivermectin and vitamins can be up to 90% effective in preventing COVID-19. And for patients who get COVID-19 it can greatly reduce symptoms and the likelihood of dying. Go to the FLCCC Alliance site and watch the video of testimony before the Senate on Dec 8th. Download and read the summary of the human studies on effectiveness from Brazil, France, Argentina, India, US, etc, then send it to every loved one you know plus every doctor or nurse, since many are too busy to have seen these Ivermectin studies. The side effects are well known. They can prescribe it off- label. It’s common and legal to prescribe off- label, but they won’t if they haven’t read the studies on Ivermectin protocols from the last 3-4 months. My doctor proactively contacted all his patients about the effectiveness of Ivermectin in protecting you against COVID-19. I’ve been on it since before Thanksgiving.With many not willing to take the vaccines, Ivermectin is a great bridge until the vaccines prove themselves safe. Ivermectin is going through peer reviews, but these bureaucratic organizations aren’t about to do their homework quickly. Educating your doctor about the recent studies on Ivermectin effectiveness is a much faster route to keeping your self and loved ones well or to help them heal more quickly. And once we clear out the ICUs with patients going home, we can open us ALL our business.

  • Almost all of these masks are made in China. Does that correlate to anything? More people are wearing them and the rate keeps going up.

  • Science is so neat because you have to be aware of the actual question and what it means. As a Canadian Scientist I had to deal with science fraud and received a letter from the US surgeon apologizing for how badly I was treated when I reported NIH fraud.Note how they compare Covid 19 to MERS and SARS but NOT the flu . I must for comparison give you the Case Fatality Rates /CFR of the 2018 flu vs 2020 covid 19 and ask you to think and draw logical conclusions . CFR for 2018 flu was 8.5 K deaths divided by 39K case= 0.218 WHILE CFR for covid 19 last Stats Can numbers was 12.8K deaths divided by 500K cases= 0.026 OR the flu was almost TEN TIMES more deadly than covid !!! you can talk all you want about infectious rates BUT you MUST consider the DEATHS these upper respiratory diseases cause.Using CFR covid compared to flu is a mild infection. I have my own opinions on the over all picture https://medium.com/@edwardagreenhalgh/covid-19-world-economic-collapse-under-the-rule-of-law-the-lock-downs-are-illegal-and-not-a-real-556c4b9b4ca8

  • How about you start getting a clue about the real virus 5555 geehhh at 60 miliwaves it binds to oxygen…they aren’t for faster phones.

  • The real virus is 5555geehhh…no one is talking about that …60 millimeter waves bind to oxygen…people are dying in the hospitals….where they make money off C-19. Also where is 5 geeeh in the hospitals now? Inquiring critical thinking minds would like to know!

  • There is no spread of the virus period…the whole thing is nothing but positive tests.

  • This article is a lie and Ben Cabrera is a liar. The study states: “However, presymptomatic transmission does occur”.

    • This is not the full article, it is a summary. It alludes to the fact that there were not enough subjects measured. If we had access to the full study we’d know how many people were studied. For this to have real validity, it needs to be replicated with a high N

  • To the person who said that the Attack Rate was higher for the flu. The article you quoted said “Overall, we found that approximately 1 in 5 unvaccinated children and 1 in 10 unvaccinated adults were estimated to be infected by seasonal influenza annually,” BUT With Sars Cov 2 we have an average of 18.1% which is higher and also older people tend to get it more than children. So it’s a bit opposite of the flu! https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0240205

    And for those of you who are making FLU comments. Here is the Genome for a variation of Sars Cov 2 and Influenza. If you can read these and actually tell me the SIMILARITIES AND DIFFERENCES then you can make your flu comments!!!

  • >