Sources:
- Nature study, 20th Nov https://www.nature.com/articles/s41467-020-19802-w
- Maria Van Kerkhove, head of the WHO Emerging Diseases and Zoonosis unit https://www.youtube.com/watch?v=NQTBlbx1Xjs
- Fauci in 2018 https://www.youtube.com/watch?v=vrAvjU2LBkg&feature=emb_titl...
I, asymptotic young person with nCoV 2, am spreading it today. The “yet” part is completely irrelevant to this point in time.
In colloquial usage, asymptomatic encompasses presymptomatic. In technical usage, they are different.
If you develop symptoms, then when you were a carrier before then, you were presymptomatic, rather than asymptomatic.
Of course, whether you go on to develop symptoms or not, its still highly pertinent information if asymptomatic spread is not a major driver of infection. As long as you self isolate upon symptom onset that should be enough. It does call into question whether isolating the apparently healthy is an evidence-based public health policy intervention though.
We used to think true asymptomatic infections (never develop any symptoms but test positive) were ~50% of those infected. More recent research puts it at closer to ~20%. Again, some reporting bungled this by reporting studies from controlled populations (like a cruise ship) before they knew if cases were asymptomatic or pre-symptomatic, causing people to quote the number as the former, when it was really a mix.
COVID spreads like wildfire by pre-symptomatic people. There are mountains of evidence to support this. Spread by asymptomatic people is speculation.
> Of course, whether you go on to develop symptoms or not, its still highly pertinent information if asymptomatic spread is not a major driver of infection.
Not sure, but I think you may be using the word "asymptomatic" to denote pre-symptomatic in this sentence.
> As long as you self isolate upon symptom onset that should be enough.
It is not enough.
There is absolutely a difference between 'yet to have' and 'never will have' but I think it is potentially confusing to attempt to delineate between asymptomatic and "pre-symptomatic".
The main concern with messaging that causes confusion in this regard is that a superficial reading of "asymptomatic doesn't spread virus" would imply that if you aren't symptomatic, you aren't a danger.
And the viral load is high two days before the symptoms onset. If you want a proper RCT about it, good luck approving it in an ethics committee.
Asymptomatic has a strict definition. You get the virus and nothing happens to you. This is what the WHO and Fauci are referring to.
But most "asymptomatic" cases aren't. They are either paucisymptomatic (you have mild symptoms - maybe too mild to notice) or pre-symptomatic.
Obviously if people were only contagious if showing symptoms, the pandemic wouldn't be.
> Obviously if people were only contagious if showing symptoms, the pandemic wouldn't be.
I don't think that is obviously the case at all. It would have to be proved. The dominant vectors of contagion are not yet well understood - we could be dealing with very highly infectious airborne virus, that is capable of spreading widely from a relatively small number of symptomatic and pre-symptomatic super spreaders.
The fact remains that current public health interventions orientate around isolating individuals whether they are symptomatic, asymptomatic or paucisymptomatic. Moreover, to greater and lesser degrees we also isolate the healthy, assuming them to be asymptomatic in an abundance of caution. Considering the negative non-covid related knock on effects of these policies its at least worth investigating isn't it?
The calculated R0 does not support this theory. Measles works this way. R0 for Measles is > 10
> that current public health interventions orientate around isolating individuals whether they are symptomatic, asymptomatic or paucisymptomatic
Everywhere, the restrictions are higher if you were tested and/or is suspected of having Covid. Of course a lot of people DNGAF about the restrictions, which is part of the problem.
Again, if your theory that people showing no symptoms do not transmit the disease then it should be super easy to go around and start finding people spreading it. But it isn.t
People will say to themselves well, it's just a cough right? Just a cough. I can't have COVID-19 that's something other people get, those people are sick but I'm healthy, this is just a cough. And that allows the virus to spread.
Or you notice them but because they also match symptoms of colds and allergies, and you’ve been getting them on and off for months, you assume they aren’t COVID.
I don’t think there has been an interval longer than a week since February during which I didn’t have at least a couple symptoms that could have been COVID.
I’ve not had the taste/smell loss, and all my contact with other people has been masked and brief, and I’m in an area where spread has been low, so I’ve probably not had it, but I wish we had widespread cheap testing so I could know.
Exactly. I have occasionally runny nose combined with sporadic sneezes and coughs pretty much every winter. If someone like my had so "mild" COVID symptoms they would consider themselves asymptomatic (paucisymptomatic?), and rightfully so. (My actual COVID symptoms were not as mild, but not very serious either.)
It's remarkable the number of people anecdotally reporting similar symptoms - often out of character for otherwise robustly healthy individuals. I'm guessing some sort of psychosomatic response to the year's stresses.
I have been having the same, but the main reason why I notice it now is that every time I have any symptom, even the mildest of them, I take notice and consider the possibility of Covid, whereas in past years I would forget about them if even notice at all.
For context, I'm a fairly healthy individual who hasn't seen a GP or other medical doctor in at least a couple years, probably longer. Last time I've been to one was because of exercise-related injuries.
This is hypochondria isn't it? A pathology in its own right, no doubt caused by current events.
It's not hypochondria, it's simple awareness.
That being said it seems the most specific symptom is loss of smell/taste so unless you have that it's probably something else (disclaimer: not a doctor and this is not medical advice)
https://www.theglobeandmail.com/canada/toronto/article-stude...
Still not obvious one way or the other about whether these students and staff are spreading it amongst themselves or if they all got it from other symptomatic cases in the community and independently brought it to school with them. But either way, it's sobering how much of it is going undetected.
It wouldn't make any sense at all. The reason is that not only do older people have a greater risk of dying from Covid, they also have a much higher risk of being hospitalized[1], and remember the justification for the extreme measures we've taken and continue to take is the fear we will overwhelm our health care systems.
[1] https://www.cdc.gov/coronavirus/2019-ncov/covid-data/investi...
> JCVI has considered a number of different vaccination strategies, including those targeting transmission and those targeted at providing direct protection to persons most at risk. In order to interrupt transmission, mathematical modelling indicates that we would need to vaccinate a large proportion of the population with a vaccine which is highly effective at preventing infection (transmission). At the start of the vaccination programme, good evidence on the effects of vaccination on transmission will not be available, and vaccine availability will be more limited. The best use of available vaccine will also, in part, be dependent on the point in the pandemic the UK is at. Given the current epidemiological situation in the UK, all evidence indicates that the best option for preventing morbidity and mortality in the initial phase of the programme is to directly protect persons most at risk of morbidity and mortality.
https://assets.publishing.service.gov.uk/government/uploads/...
2. By what mechanism do you imagine it got into the nursing home without that mechanism also working to spread it to outside?
Indeed this paper found association between viral load and symptoms - hospitalized patients are shedding less virus
Some flu vaccines come in the form of a nasal spray, which does induce an IgA response. I don't know why COVID vaccines are administered parenterally instead, I'm sure there are good technical reasons. Given the virus's possible neurological involvement, maybe it's a bad idea to deposit it so close to the olfactory bulb.
0: https://en.wikipedia.org/wiki/Immunoglobulin_A#Secretory_IgA
However, the science is the easy part here. It gets complicated once politics comes into play. Pretty much all scientists I've spoken or listened to say that they assume that the spread will most likely be at least severely limited through the vaccines. That's because they don't have any other explanation than a reduced viral load that could explain how the vaccines actually work in preventing sickness, and a reduced viral load would also mean a reduced spreading capability. However, not knowing something does not mean it can't exist: it is not impossible for there to be some unknown way in which these vaccines may potentially prevent sickness without also limiting viral spread. And scientists usually want to be scientifically correct, so they don't go out and declare something as fact that they just carefully "assume" to be the case.
This "known unknown" of effectiveness in limiting viral spread is now actively being used by politics, especially those people coordinating protective measures in governments, as a convenient escape hatch out of a problematic situation. That situation is: how do you explain to someone who just got vaccinated that he/she should still adhere to all the protective measures like universal mask-wearing and limiting personal contacts? Because even though there are rational reasons for doing so (first, the vaccines need two shots and some weeks of time to actually build up protection, and second, if a significant portion of the populace is exempt from all the protective measures and their burdens, this incentivizes the remaining, non-vaccinated part to also "exempt themselves", because constraints enforced on all citizens are much easier to follow than constraints only enforced on half of all citizens) there will be a strong impetus within each individual to not follow protective measures and rules anymore, once vaccinated and thus "protected" from the virus. And besides that psychological effect there's the overarching problem of the constitutional impossibility of enforcing wide-ranging limitations on constitutional rights onto people that is not justifiable anymore, once an individual in question can provably no longer spread the virus. Because of all of this, politicians (rightfully) fear the situation that we're going to be in in a few months time, when a significant part of the populace, but not enough for herd immunity, is already vaccinated. An assumption of a possibility of transmission even with vaccination is a godsend in that situation.
Additionally, for the immune system to respond, the infection has to happen first -- the virus has to spread through the cells of your body. We already know that the people are indeed infectious before their immune system response makes the symptoms. The delay in response has to exist even among the vaccinated people.
So what is sought after is a proof of sterilizing immunity, and there's no such still. I've read that the UK plans to evaluate the evidence for that in the following months by tracking the people who get the vaccine, which sounds good.
Because of this, for practical purposes, you either have to arbitrarily set a threshold at which someone is considered non-infectious, ignoring that it is not impossible for that person to infect someone. Or you have to stop talking in absolutes entirely and just talk about probabilities.
The same is with the possibility that a vaccinated person infects somebody else. There is some point behind which it could be said that some vaccine has "sterilizing immunity" even if some small level of viruses could be present somewhere. For the current vaccine, the question is if the viral load in some point after the infection is decreased at all, and if it is, how much.
At the moment, however, it's simply not known if, in this case, Pfizer vaccine provides sterilizing level of immunity, if, then when, and in which percentage of the vaccinated. At the moment more or less we just know that the vaccinated are less probable to develop symptoms. Efficacy of 95% here means only one of 20 vaccinated develops symptoms when exposed to the virus, so we know that it's also probable that at least 1 in 20, even after being vaccinated, could be able to infect somebody else while being in the "pre-symptomatic" phase (as it is believed by the researchers that one transmits the virus before one's symptoms starts). We also believe that asymptomatic are also able to transmit. We don't know how much the vaccine affects the transmission that could occur when a vaccinated person is exposed to an infected one, and then later comes in close contact with other unvaccinated persons.
ICU beds are extremely expensive.
It is a very invasive method of keeping someone alive and is only used in emergencies. Rehabilitation also binds resources.
Edit: Do you work at the JR by any chance? Asking as another Oxford Male based nearby!
https://academic.oup.com/biomedgerontology/article/60/1/129/...
Do you work in a hospital? do you know any ICU people? I think you are confusing palliative care with ICU
American overtreatment is busting out MRIs for a standard sprain, routine CAT scans, dishing out opiates for anything more than 2weeks
The uk is vaccinating according to risk of death, and risk of occupying a hospital bed first. Not the risk of catching or passing it.
THe big concern in this pandemic has been hospital usage. once your hospital is full everyone starts dying not just covid patients. We were about two/four weeks away from collapse in london in april.
Although you can argue that keeping hospital beds free saves a lot of QALYs, it's harder to argue that care homes have a lot of QALYs to save.
And, it's not obvious that care home patients are the first to occupy hospital beds (I'm unsure about it); care home patients with COVID have tended to die in their care home.
Not true at all. They may have fewer life years left, but they're orders of magnitude more likely to die from Covid, so preventing a Covid case in this population actually saves more QALYs than preventing a case in a younger healthy person, statistically speaking.
It doesn't mean they're right, or even that they're all in agreement on the best course. But they're tasked with making a decision that absolutely has to be made right now, and can't wait on getting a complete picture.
Also, the workers in the homes are put at significant risk due to this as well.
There is a heck of a lot more people who are at risk of being superspreaders, not even mentioning the huge number of middle aged people going to protests against a diseases existence. You won't get those people vaccinated. They will massively contribute to the spread.
Additionally, vaccinating risk groups in the high age category first lets you spot complications with the disease more early and it's ethically somewhat better to risk long-term vaccination issues with 90+ year olds than 20+ year olds, as one of these groups will have to suffer the consequences for a shorter time. It may sound harsh to make comparisons like that but you'll have to make decisions like that in a medical environment.
No, it makes sense to give this to people who are most at risk of spreading it to people who are most at risk of dying from it. Thus anyone in and around aged care.
That's incredibly likely but it's not what the trails tested, and so we can't rely on it.
When the vaccine has been rolled out much more widely we'll be able to gather the data to test that hypothesis using surveillance data.
2. The study of the vaccine thus far evaluated immunity, not transmission; not the same thing.
3. A 90 year old is far more likely to die of the virus regardless of whether she is infectious.