It is always difficult to determine exact numbers of asymptomatic Covid-19 cases because it can be difficult to distinguish asymptomatic cases from paucisymptomatic cases on the one hand and presymptomatic cases on the other: testing positive whilst asymptomatic is not the same as subsequently remaining asymptomatic.

Some of the early estimates for asymptomatic Covid-19 cases (of which the highest estimates put them at ~80% of total infections) were the consequence of studies that had no or little follow-up with the test subjects. Later studies have significantly revised down these estimates. Some meta-analyses have produced central estimates for asymptomatic cases as low as 17%. But such meta-analyses are fraught with their own problems to do with study methods and data comparability and should be treated with caution. However, it's clear from later studies that have followed-up with test subjects that around half of all subjects with positive tests when asymptomatic later went on to develop symptoms; i.e. around half of people initially defined as asymptomatic cases are in fact presymptomatic. And in the UK, the Department of Health and Social Care currently reports that around a third of Covid cases are asymptomatic.

Estimates suggest that most people have still not contracted Covid-19. This estimate from early this year (yes, I accept that it is seven months old) puts the number of total people infected at ~20% in England. In some (mostly very densely populated) areas of England the estimates go as high as ~50%, but even so. Unless the cumulative incidence in michaelk's area is exceptionally high, it is very unlikely that his family contracted Covid-19 and didn't develop symptoms. As they have not had symptoms, chances are they have not had Covid-19.

Vaccinations might complicate this picture in the future as recent studies from the UK indicate that full vaccination reduces the chances of symptomatic infection (e.g., the Pfizer vaccine was shown to be >80% effective against symptomatic infection for all variants) as well as >90% effective against hospitalisation (even against the Delta variant). But an Imperial College London led REACT study has also shown that full vaccination reduces by half the transmission of the Delta variant (the most infectious "mainstream" variant of SARS-Cov-2 thus far identified).

https://www.sciencemag.org/news/2021...er-if-they-are
and by the way.

I would rather my dependents take a vaccine scheduled for emergency use and live, than not take it and die. You clearly have other priorities. I hope you survive them.

That may not actually be the case.

The latest policy recommendations from the CDC are inspired by studies suggesting that asymptomatic vaccinated individuals can be a significant source of infection. Here's a NYT article on the issue, which unfortunately contains a lot of half-truths and inaccuracies (calling asymptomatic, vaccinated individuals "fully immunized people", which they clearly are not), but the bottom line is that there is in fact evidence indicating significant asymptomatic spread by the vaccinated.

Sure. But I would bet my life that it's still lower than unvaccinated people. Point being nothing is 100%. You do what you can. Perfection is impossible. Even a 1 or 2 percent reduction still translates to a load of folks being saved or whatever when you multiply it out to country population sizes. What is life worth?

Same thing with masks. People say they don't work. They are wrong. That is a proven fact. They do work. Are they 100% guarantee? No. But if they reduce it a bit then in the big picture it adds up to alot of folks.

Sadly with the focus on numbers and tracking people are using that to give themselves a reason to not do everything they can to help both themselves and everyone else. It's statistics. Anyone can read a chart. But not everyone knows how read it properly. Is why there is an entire field devoted to statistical analysis.

*EDIT* A final note. People seem to have little trouble with the flu vaccine. It averages a 40-50% effectiveness. They live by it. No one claims it's any type of government control, no one sane anyway.

A couple of interesting links

oral vaccine
https://www.jpost.com/health-science...vaccine-674563

treatment
https://www.jpost.com/health-science...-5-days-675961

Can you cite a study showing this? A single study will do, preferably one involving real-world scenarios, or perhaps a statistical analysis of the spread in masked vs. unmasked environments?

Because there are quite a few studies out there; there's the Danish study on mask efficacy with regard to the spread of SARS-CoV-2, and there's a fairly old South Korean surgical mask study regarding viral spread in general, and then there's the huge German statistical analysis, but they all show the same: Masks simply have no effect(*).

And think about it: It would actually be really strange if they did work! SARS-CoV-2 is an airborne virus with a diameter of .12 µm or less, which means it will easily pass through the filter of even an N95, which is said to stop 95% of particles with a diameter of .3 µm or larger, but that's more than twice the size of this virus.

Surgical masks are made for stopping droplets, and in that regard they do a fine job, but you don't actually breathe through them. And even if you did, the effect would again be marginal at best due to the small size of the virus. And those home-made cloth masks... I mean, that's just silly.

To me it seems there are other factors at play here. I don't see politicians or health officials ever reversing their stance on masks, at least not in public, regardless of scientific evidence. Because that would be admitting they were wrong and that the earlier mandates and recommendations were ineffective, unnecessary, and not based on evidence.

(*)You can always say, "well, some viral particles will be caught by the mask fabric, so we can't say that they're entirely ineffective", but by that standard chicken wire mesh is also "not entirely ineffective." They question is, do they make an actual difference in slowing the spread of SARS-CoV-2, and by all accounts they do not.

https://jamanetwork.com/journals/jam...rticle/2776536

https://science.sciencemag.org/content/372/6549/1439

It depends on many factors I guess. However, I don't know if anything hanged since the viral load is so much greater with the delta variant. Social distancing is also important.

Fair enough. But since droplets are the main carrier then yes masks work well. If it was pure airborne then you'd be correct. Masks block droplets.


Unless of course that has changed.

I would argue that the first link is indicative of the problem. It refers to respiratory infections in a hair salon, and whether a a causative link could be made to people wearing face masks. If that doesn't seem like a "study" that falls short of just about every scientific measurement, I don't know what does.

Here's a recent (2021) Norwegian review (in English) of currently available studies regarding the effectiveness of face masks when it comes to the spread of COVID-19. The summary says it all (emphasis mine):So that's 43 recent reviews/studies, out of which 42 was basically rubbish. But they still get quoted in the media.

I'd go for the older studies, the ones made back when there was no COVID hysteria, and no-one had an invested interest in getting a particular result. Or statistical analyses of actual, high-quality data from parts of the world where the infection has basically spread to everyone, like Gibraltar.
Depends on what you mean. SARS-CoV-2 can hang in the air long after an infected person has left the room. One study found concentrations high enough to cause an infection even after 3 hours. Outdoors it's another matter entirely.

I'm sorry to keep harping on about this, but getting this wrong can have some pretty serious consequences. For instance, if someone thinks they can visit grandpa in the nursing home as long as they wear a face mask and stay at least 6 feet away, they're wrong. And if they think they cannot possibly carry the infection because they took a PCR test and it came up negative, they're also wrong.

And it is, so I am.

For some weird reason, for a long time the World Health Organization actually tried to argue against the science when it came to this particular issue: Link (The New York Times again, in July 2020, and here's an archive link for those who cannot get past the paywall.)

enorbet, you have my sympathy.

As for the rest, I'm old enough to remember pictures on my television of children with polio depending on iron lungs for life. Vaccines made those pictures go away. QED.

There is something called the social contract which seems to have been forgotten by many. Society has a responsibility to its members, true, and in return its members have a responsibility to society. That includes, in my opinion, protecting their own health and the health of others. If that means getting vaccines, get vaccines.

wpeckham, with all due respect to you and to the fervency of your apparent beliefs, "I will cheerfully take my chances of dying ... as I necessarily do, each and every day." Fearmongering won't influence my decision-making at all.

I know that these "treatments" (sic ...) are "anything but(!) 'vaccines.'" I know that they are manifestations of a strategy that has never been approved for use in humans, and which most likely never would have been had a certain politically-connected doctor come up with what I frankly consider to be a criminal idea. I understand more than enough about this strategy to know that I will never allow it to enter my body. I will never be injected with anything that causes my body to turn against itself.

But – "that's my body, not yours." Therefore, that is my "informed [refusal to give ...] consent." Which is, under actual Federal law, still my sovereign choice. Under that law, no one may be coerced into taking any medication or undergoing any medical treatment.

And so, "if the consequences turn out to be that I die," I just hope that it happens entirely without w

I don't recall anybody arguing against vaccines in general.

Your "QED" does come across as resembling a certain logical fallacy. Surely, vaccines are like all other medication: Taking it should involve informed consent.

Edit: I see sundialsvcs beat me to it with regards to the last point.

Some numbers for deaths here: https://www.cdc.gov/nchs/nvss/vsrr/c....htm#SexAndAge

My impression from there is that the death rate among older people has dropped a lot more than among younger people. So relatively more young people dying, but not so much in absolute terms.

I don't think that contradicts the claim that vaccines slow the spread though. Also, we should remember that observational studies have limitations. Apparently 85% of the cases were male, but nobody is saying that the delta variant preferentially targets males...

https://slate.com/human-interest/202...ter-diary.html
https://www.cdc.gov/mmwr/volumes/70/...cid=mm7031e2_w

Not really, the origins of mNRA started in the early 1990s as a cure for cancer. while the NIH was involved with mRNA research which started over 15 years ago it was Dr Barney Graham that was actually responsible with the breakthrough. Dr Fauci is just the director of the NIH. Your correct early research did lead to excessive inflammation in animals but that was overcome over 10 years ago.