More coronavirus carriers show no symptoms

New advice on asymptomatic transmission increases the push for mask wearing.

Red person in a crowd of people

It is now believed that 40 per cent of coronavirus carriers show no symptoms and 75 per cent of them can pass on the deadly disease.

The US Centres for Disease Control and Prevention (CDC) now advises that the rate of people infected with COVID-19 who are asymptomatic has risen from 35 per cent to 40 per cent, Business Insider has reported.

There is some confusion about the definition of ‘asymptomatic’.

“Some people who are infected never develop any symptoms at all. These patients are considered true asymptomatic cases,” Professor Monica Gandhi, from the University of California, San Francisco, told The Conversation.

“When people do get sick from the coronavirus, it takes on average five days, and as many as two weeks, to develop symptoms that can range from very mild to extremely dangerous. The time between initial infection and the first symptoms is called the pre-symptomatic phase.”

Pre-symptomatic coronavirus carriers shed the virus at a high rate. As the virus sheds heavily in the nose and mouth, people without symptoms most likely spread the virus via droplets of saliva and mucus sprayed into the air when they cough or talk.

In June, Prof. Gandhi said there were hints that transmission by asymptomatic or pre-symptomatic patients was a “major driver” of the pandemic.

She says social distancing and lockdowns work to limit asymptomatic spread, but since the virus sheds heavily from the upper respiratory tract, universal mask wearing is the best tool to limit transmission.

Behavioural scientist Daniel Oran, co-author of a study from the Scripps Research Translational Institute, agrees that wearing mask is vital. He says if 40 per cent of cases are asymptomatic, “the probability is almost a flip of a coin on whether you’re going to have symptoms. So, to protect others, we think that wearing a mask makes a lot of sense.”

His co-author also backs widespread virus testing. After analysing testing studies on 16 diverse cohorts from around the world, Professor Eric Topol says the “silent spread” of the virus makes it more challenging to control.

“Our review really highlights the importance of testing. It’s clear that with such a high asymptomatic rate, we need to cast a very wide net, otherwise the virus will continue to evade us,” he said.

Nerosciencenews.com.au reported that asymptomatic individuals might be able to transmit the virus for longer than 14 days.

“The viral loads are very similar in people with or without symptoms, but it remains unclear whether their infectiousness is of the same magnitude. To resolve that issue, we’ll need large-scale studies that include sufficient numbers of asymptomatic people.”

Other studies previously indicated “more than 50 per cent of infections were attributable to people not exhibiting symptoms”, ABC News America reported.

“Even if all symptomatic cases are isolated, a vast outbreak may nonetheless unfold,” the authors of one study wrote.

“Understanding how silent infections that are in the pre-symptomatic phase or asymptomatic contribute to transmission will be fundamental to the success of post-lockdown control strategies,” said experts from America’s National Academy of Sciences.

On 9 July, the World Health Organisation accepted that the coronavirus may be transmitted through aerosols, which can linger in the air. Previously, more than 200 scientists worldwide had campaigned for the recognition of aerosols as a mode of transmission.

The CDC is also concerned about how the news of asymptomatic carriers affects schools.

Children are at lower risk of suffering serious illness and death from COVID-19, but they can be asymptomatic carriers.

The CDC’s updated ‘infection fatality ratio’ estimates that 0.65 per cent of people infected with COVID-19 will die.

Have you embraced the wearing of face masks? Do you believe they should be mandatory?

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    COMMENTS

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    Steff
    15th Jul 2020
    10:42am
    Keep the fear going.Dont give the Sheeple time to relax before hitting them with another coronavirus horror story.
    The Dr Mengeles in our health services are determined to keep us locked up forever for whatever nefarious reasons
    Triss
    15th Jul 2020
    10:50am
    Yes, Steff, perhaps politicians should be put in lockdown for a few weeks we’d probably get a better way of dealing with the virus then.
    leek
    15th Jul 2020
    11:25am
    Steff & Triss I have had 2 experiences with ICU. Myself for 10 days when I was 22 and my daughter 4 years ago. Currently in Melbourne there are 21 people on ventiltors(Virus). My guess is that there can't be more than 100 ICU beds in all of Melbourne. If all of the ICU beds get taken by people on ventilators, then you had better pray that you do not have a heart attack/stroke/car accident as there will be NO ICU bed for you if this virus does not get under control.
    This is what the governments of the world(most) are trying to stop. They are trying to save their health systems from collapsing. so that the system is there for everybody regardless of what problems they have.
    Mez
    15th Jul 2020
    12:00pm
    So you are volunteering to be the next death statistic!
    Everybody gets their just reward sooner or later!
    Horace Cope
    15th Jul 2020
    12:01pm
    Totally agree Steff, reading the article throws up words like "believed" and "hint" which are not words generally associated with scientific conclusions.

    Triss, I see you have taken another general swipe at politicians without any specifics.
    Sceptic
    15th Jul 2020
    3:01pm
    I suppose Steff, Triss and Horace are in the "I wont wear a mask as it will not stop me catching the virus" brigade. Are they just too thick to consider that they may be asymptomatic carriers and could prevent one or more new cases of "community contagion?"
    Horace Cope
    15th Jul 2020
    3:08pm
    You've drawn a long bow there, Sceptic, by suggesting that I don't wear a mask. Unlike you, I don't resort to personal vilification.
    diamond
    15th Jul 2020
    5:43pm
    Leek you forgot to mention that governments over the years have closed hospitals instead of building more to cope with our increase in population. There were more hospitals when I was a child in Sydney than there are now.
    Farside
    15th Jul 2020
    9:46pm
    Leek what's your basis for guessing less than 100 ICU beds in Melbourne? At March there were 2,229 Australia wide, 476 of these in Vic.
    https://multitools.newscdn.com.au/multitools/slider/content/1584664801588/NED-1434-Australias-ICU-Beds_SIrTj6xJQ.jpg

    In April, the Vic government announced program to add another 4,000 ICU beds. https://www.premier.vic.gov.au/new-beds-open-across-victoria-in-pandemic-capacity-boost/

    600 new ICU beds are reported to be coming online this week.
    https://www.afr.com/politics/federal/icu-capacity-more-than-doubled-as-victoria-braces-for-surge-20200714-p55bxq
    Blossom
    16th Jul 2020
    1:21am
    diamond.
    It's like they built a new Hospital in Adelaide and it has less beds than the old one does because they made most of the rooms private ones (one patient per room).
    The old one the electricity and plumbing needed the whole lot to be replaced and going by the age of the buildings there would be a lot of asbestos in them too.
    Farside
    16th Jul 2020
    12:11pm
    Vic Health Minister just reported more than 1000 available ICU and critical care beds across Victoria
    Sceptic
    16th Jul 2020
    1:35pm
    Horace, if you are not anti-mask, i apologise, but your response to Steff was "I totally agree." which was agreeing with an extreme opinion post.
    Incognito
    16th Jul 2020
    2:27pm
    Why is it an extreme post Sceptic? That is your opinion?
    justjanet
    15th Jul 2020
    11:07am
    My question is if you’ve been tested found negative x twice how do you know your not A a carrier or B going to catch it anyway
    Mez
    15th Jul 2020
    12:07pm
    EXACTLY!
    INCUBATION PERIOD FOR THIS VIRUS, SARS COV- 2 IS 2 - 20 DAYS so even with a negative test result, you could be infected by walking sick person or an asymptomatic person the day after your test so WEAR A MASK and use all other precautions even after lockdown and restrictions are eased until you are vaccinated!
    Steff
    15th Jul 2020
    12:55pm
    Shove your mask and stick your totally untested and DNA altering vaccine
    Tanker
    15th Jul 2020
    2:22pm
    Ah Steff an unbeliever. An effective vaccine has not been developed at this point in time. Vaccinations have eliminated some truly killer diseases and helped control a number of others. It is so improbable that when a vaccine is finally shown to be safe that will include the fact that it is does not alter the DNA. I have been vaccinated a number of times against various diseases and have no hesitation of being vaccinated in the future.
    Masks, it is now being strongly recommended, are worn when in closed areas where there numbers of people such as supermarkets. Only those with a total lack of responsibility will not wear a mask.
    Sceptic
    15th Jul 2020
    3:04pm
    Steff; Stupid is as stupid does.
    Farside
    15th Jul 2020
    9:57pm
    Justjanet, if you have your two swab tests returned negative results it just means you were negative at the time the test was taken. You need an antibody test to tell whether you might have had covid however these tests are presently considered unreliable. In any event it is still early days and even if you do have antibodies, we do not know how long they will last and whether they will provide immunity to the strain at the time, hence the interest in a vaccine.

    And to make matters more confusing, it has been thought incubation period is 2-20 days as Mez says but then there is the issue of the Venezuela boat crew. Crew was tested, did two weeks in quarantine, spent 35 days at sea without contact and came back with 57/61 covid positive. So follow the drill, you are most likely to catch at home or around those you spend time with. Self distance, practice good hygiene, wear a mask when you cannot distance.
    Mez
    15th Jul 2020
    11:58am
    Figures are consistent with what I have previously read as being in the range of 30 - 50%!
    Some apparently think that testing just increases the number of cases but that is FAR FROM THE TRUTH!
    EACH ASYMPTOMATIC PERSON TESTED AND ISOLATED HAS THE CAPACITY TO MULTIPLY THE NUMBER OF CASES BECAUSE THEY ARE INFECTIOUS TO OTHERS!
    That is why you should WEAR A MASK because there are many stoopids who do not socially distance in public, especially in supermarkets!
    Dabbydoos
    15th Jul 2020
    1:03pm
    Mez I agree with you wholeheartedly. Such a small thing as wearing a mask would protect so many, make it mandatory.
    Placido1
    15th Jul 2020
    1:42pm
    Steff and Triss, didn't you read about the 30 year old Texan who thought like you that it is a hoax.

    He went to a "Corona Party" that had people who tested positive, he caught it and DIED from it, such stupidity, is that what you want Australians to be like??

    I shall wear a mask for myself and OTHERS.
    Placido1
    15th Jul 2020
    1:45pm
    I guess the Anti-Vaxxers don't care who dies as long as they can cling to their ill conceived scientifically inaccurate weird belief systems, probably do not believe in climate SCIENCE either.
    Sceptic
    15th Jul 2020
    3:04pm
    Placido, no, they are just selective in which science to believe.
    arbee
    15th Jul 2020
    3:15pm
    This is rather scary, but if true doesn't bode well for most of us reading these articles if we have a severe case of the virus.

    Written by a nurse who works with ventilators:
    For people who don't understand what it means to be on a ventilator but want to take the chance of going back to work....
    For starters, it's NOT an oxygen mask put over the mouth while the patient is comfortably lying down and reading magazines.
    Ventilation for Covid-19 is a painful intubation that goes down your throat and stays there until you live or you die. It is done under anesthesia for 2 to 3 weeks without moving, often upside down, with a tube inserted from the mouth up to the trachea and allows you to breathe to the rhythm of the lung machine.
    The patient can't talk or eat, or do anything naturally - the machine keeps you alive. The discomfort and pain they feel from this means medical experts have to administer sedatives and painkillers to ensure tube tolerance for as long as the machine is needed. It's like being in an artificial coma.
    After 20 days from this treatment, a young patient loses 40% muscle mass, and gets mouth or vocal cords trauma, as well as possible pulmonary or heart complications.
    It is for this reason that old or already weak people can't withstand the treatment and die. Many of us are in this boat ... so stay safe unless you want to take the chance of ending up here. This is NOT the flu.
    Add a tube into your stomach, either through your nose or skin for liquid food, a sticky bag around your butt to collect the diarrhea, a foley to collect urine, an IV for fluids and meds, an A-line f to monitor your BP that is completely dependent upon finely calculated med doses, teams of nurses, CRNA’s and MA’s to reposition your limbs every two hours and lying on a mat that circulates ice cold fluid to help bring down your 104 degree temp.
    Anyone want to try all that out? Stay home. Stay safe and well!
    leek
    15th Jul 2020
    4:53pm
    Its a shame we cannot post photos, As I have a photo of my daughter when she was on a ventilator 4 years ago for 48 hours. It is so terrible that I was not allowed to be with her when they took the ventilator out.
    Watching your own child on a ventilator is the worst thing you will ever see. I knew my child was going to survive. But in ICU she was surounded by people that were struggling to survive. Families crying every where. It was terrible.
    Now with Covid-19. if your loved one is on the ventilator you are not allowed to be near them because of the virus, and they die alone.
    Good Luck to those that do not believe in the seriousnous of this virus,
    Farside
    15th Jul 2020
    10:03pm
    If you are elderly and in ICU with covid then you have around a 50% chance of dying when they call for the ventilator. Fortunately knowledge of the disease and treatments are improving by the month.

    15th Jul 2020
    4:55pm
    Life without freedom is not worth living. Presently our freedom is taken away from us by the government in many areas just because of one more tiny virus. I have a news for you - people have been living with viruses and bacteria forever. I tell you even more - without them we would not exist at all.
    And for those desperately afraid of dying of COVID-19 - you ARE going to die. Virus or not virus.
    It is really funny reading here your posts. The most miserable life someone lived the more she or he is afraid of dying. So, yes, close all borders, shut all doors, stay in the dark and live in your own prison forever.
    Cogsen
    15th Jul 2020
    5:42pm
    I truely believe this current surge or spike in covid19 in Melbourne has a lot to do with the recent BLM protests in Melbourne but no one want to admit it.
    Incognito
    16th Jul 2020
    2:09am
    There was no evidence of that.
    Farside
    16th Jul 2020
    12:14pm
    Cogsen, why would you expect someone to admit to your beliefs especially if they do not share them. You need to come with evidence if you want to persuade those who rely on facts to inform their opinions.
    Placido1
    16th Jul 2020
    2:01pm
    You may WANT to believe it but there is no evidence to back it up. there is evidence re the quarantine leaks.

    Given one person from victoria triggered around 40 cases in Casula (Sydney) then if people got infected during the BLM rally some weeks ago then there would have been massive outbreaks all over Melbourne.
    Hirajima
    15th Jul 2020
    6:15pm
    Thank you for those who try to post sensible, constructive and worthwhile comments, but unfortunately there is too high a proportion of individualism, selfishness and downright tinfoil-hat crazy here. I really cannot spend time in futility trying to educate people who are just stubbornly adhering to whatever brand of loony they have absorbed from every nutty corner of the internet, Alan Jones and SkyNews :P Good luck everyone, "mask it or casket", stay safe and enjoy new and interesting endeavours in iso so that you are still around to enjoy life after all this... because there will be an after for most of us, but no thanks to the freaks who are peddling their special brand of look-at-me bilgewater :( Oh and if Steff trots out sheeple one more time I am going to personally find her and arrange for her to be sheep-dipped, hehe.
    Farside
    16th Jul 2020
    12:22pm
    you might expect some on this site to catch the virus given that the readership of this site is pretty much the target audience. I don't personally know anyone that has had a case of severe covid or even tested positive (and unlikely too) however it might be interesting for people to share their experiences on here.

    "mask it or casket" – is a new expression for me, I like it.
    Placido1
    16th Jul 2020
    2:03pm
    Careful, she might think you are trying to vaccinate her.
    skinner
    15th Jul 2020
    8:24pm
    This virus is REAL & dangerous, whether anyone wants to agree or not! If you don't agree, see if you can catch it! Try not the burden your local hospital!
    alfie
    15th Jul 2020
    11:28pm
    A pandemic is like being in a war.
    In a real war you can see your enemies and when your commanding officer tells you to stay put in the trenches because there are snipers waiting to shoot you, you would stay in the trenches.
    In a pandemic you can’t see your enemies but you know it is out there ready to infect you the moment you move out. The Government has instructed us to limit our movements and keep distances to prevent the enemy from moving amongst us.
    The majority of us have being doing that but there are also some amongst us that keep moving and passing the enemy around causing some of us to get sick and others die.
    People don’t realise the fact that the Government can only do so much and that the success of winning over the enemy entirely depends on US. The longer the selfish ones don’t care the longer the enemy will be amongst us and affect everybody. What they don’t realise is that it affects them too. Are they so thick to know that? So everyone, stay in your trenches and limit your movements.
    Pres Kennedy once said “ ask not what your country can do for you but rather ask what you can do for your country”. This is that moment. Stay safe.
    Farside
    16th Jul 2020
    12:26pm
    Kennedy also said he was a donut (a Berliner) but make of that what you will. I understand your point but I don't think trench warfare and snipers are a good metaphor for a viral contagion.
    BillF2
    15th Jul 2020
    11:32pm
    As Steff points out, there is nothing positive in this article. If you're symptomatic, you will spread the disease, and if you are asymptomatic you will also do so. The so-called experts dwell on fear instead of actually doing something to reduce or get rid of the virus. Whether we like it or not, the virus is with us to stay. So minimising its effect by improving community immunity is a better way to proceed than waiting for a vaccine that may never come. The problem, though, is that many of the immunity boosters are cheap and not patented. Hence,the pharmaceutical industry, health professionals and compliant governments are not only not interested, but actively trying to discredit or prohibit medicines that might do some good.
    The current policy of trying to reduce transmission to zero may seem to be a good idea, but it doesn't solve the problem, and even if Australia were completely virus free, what about the rest of the world? How would we communicate or trade with it? We would be healthy but dead economically, and possibly physically. It's about time they realised that the Chinese handbook on how to deal with the virus, has got the last pages torn out, and they are only going to go around in circles until they stop reacting and start being pro-active toward eliminating the virus.
    Hirajima
    16th Jul 2020
    12:33am
    Bill, I am sympathetic to your concerns but dare I say your own reasoning goes around in circles and is self-contradictory quite often. Let me just address a few points, because at least you don't seem to be from the loony fringe:
    - "The so-called experts dwell on fear instead of actually doing something to reduce or get rid of the virus" - in actual fact, getting rid of the virus is exactly what many experts are working on constantly. Not there yet, but progress is made every day.
    - You speak of boosting immunity and then make the allegation that "the pharmaceutical industry, health professionals and compliant governments are not only not interested, but actively trying to discredit or prohibit medicines that might do some good" - basically, medicines are not the way to boost immunity (actually, immunity cannot be 'boosted' anyway, a better term is to say 'maintain' good immunity), but eating a balanced and healthy diet, exercise, getting enough sleep etc - all of which are within reach of the majority of people.
    - Your point about maintaining Australia virus free (if we can get back there) but being unable to trade - this definitely takes a lot of economic rejigging and clever thinking, but that's the challenge we are up against, and I have enough faith in how damned clever we Aussies are when we're up against it, and I think we are up for that challenge.
    So... finally, if we had taken the viewpoint that you are advocating in 1939-45 we would all be speaking Japanese right now and Europe would be speaking German. Instead, though, a lot of clever Aussies and our allies found all kinds of ways to fight back and we won. And we can win this too.
    Placido1
    16th Jul 2020
    2:10pm
    Bill recent medical discoveries show only a limited time of resistance to Corona virus after catching it and hopefully recovering (a few months was stated in the report) this is insufficient to provide any sort of herd immunity, all you will get is wave after wave of reinfections.

    This approach (let it rip) has not worked for Sweden, many more deaths hospitals swamped and economy still tanked even without lockdowns.
    BillF2
    15th Jul 2020
    11:49pm
    Nobody seems to be interested in discovering what makes some people resistant to covid-19 and some highly susceptible. Is it only age, or is it genetics? Maybe it could be some component of the immune system. Whatever it is, why are our health officials and scientists not interested in finding out what it is, because it would make more sense to prevent infection than to have to treat it when it is too late.
    Incognito
    16th Jul 2020
    2:12am
    I have read an article that suggests if you are normally resistant to colds and flus you are more likely not to be effected by covid.
    Farside
    16th Jul 2020
    12:44pm
    why would you say that Bill? There is plenty of research going on and being published, you just need to look at it and you can be sure there are plenty of researchers in the WHO, universities, institutes and health departments around the world. It is well known there is some cross immunity for those that have had flu vaccinations. It is know there is some immunity for those that have had other coronavirus infections (about 15% of colds). It is known that those with strong immune systems are better placed to fight the infection than those with impaired immune systems.

    What else would you have them do?

    fluvax - https://onlinelibrary.wiley.com/doi/full/10.1002/jmv.26120
    colds - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7267809/
    immunity - https://f1000research.com/articles/9-285
    Blossom
    16th Jul 2020
    1:14am
    I heard about 2 Police Officers who were on Border Control together for less than a week. Both of them have tested positive for COVID19. As testing at the orders is not compulsory they have no idea who they may have come into contact with.
    Incognito
    16th Jul 2020
    2:17am
    Too many people do not know the facts, we have so many different people saying things on TV, politicians saying things and other Government representatives, medical "experts" etc. But do we really have the truth and the real research yet to know for sure about anything this virus does or does not do? I think we have too much assumptions happening without looking at research which we need to wait for more of.

    ""From the data we have, it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual," Dr. Maria Van Kerkhove, head of WHO's emerging diseases and zoonosis unit, said at a news briefing from the United Nations agency's Geneva headquarters. "It's very rare.""

    Read more here:
    https://www.greenmedinfo.com/blog/busted-11-covid-assumptions-based-fear-not-fact?
    Farside
    16th Jul 2020
    1:01pm
    Probably the reason "Too many people do not know the facts" Incognito is the reliance upon educated guesses due to the short time COV2 and Covid19 have been researched. As you note the "facts" are still emerging and adding to the knowledge base. It takes time for researchers to gather data and run trials to drive evidence based decision making.

    CDC expert Anthony Fauci said “I’ve never seen a virus in which you have 20% to 40% of individuals who have no symptoms at all, to individuals who get mild illness, to people who are confined to beds at home for weeks with multiple post-viral symptoms, to some who require hospitalization, intensive care, ventilation, to death. This is completely unique in what we’ve experienced.”
    Placido1
    16th Jul 2020
    2:14pm
    Incognito, latest information states that around 40% of infected people (covid) are asymptomatic and 75% of this 40% are contagious for some period during their infection.

    Do not know about you bu that statistic frightens the hell out of me and has me reaching for the mask as well as the hand sanitiser.
    Virginia
    21st Jul 2020
    11:11pm
    Why are some people so stupid to be against good medical advice Wear A MASK
    Even if there are plenty of icu beds what about nurses and doctors .surely if at all possible if we follow instruction these medicos won’t be put at risk by you utter selfish grandstanding stupidity
    Just because you can or can’t don’t act like wilful ignorant 2 year olds
    Incognito
    21st Jul 2020
    11:17pm
    If you really care then you should stay home, distance from people will stop this virus because for it to be alive it needs a host. We need better quarantine measures more than masks that may or may not work.


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