[axby]

TL;DR: How did a vaccine with a reduction of hospitalizations by a factor of 20 (94%) take us from "shut everything down" to "cases no longer matter"? (Caveat: maybe for omicron it's even less severe?) Edit: specifically, from what I understand the healthcare system can't handle everyone being unvaccinated and getting the virus, it would be overwhelmed by hospitalizations. But with a 20 times reduction in hospitalizations, it can? Or was it expected that the vaccine would reduce transmission to the point where it wouldn't spread so much?

This sounds reasonable, but aren't fully vaccinated people ending up in the hospital pretty regularly too [2]? Using the 94% effective figure from the early trials, say fully vaccinated people are 20 times less likely to be hospitalized.

I don't know much about virology but I understand exponential growth. It looks like the cases are doubling every 2 weeks (edit: I guess this might even be a few days? See [0]). In a few months, almost everyone will get it. In the last two week period, won't half the population catch it? In that case, even with 100% vaccination, hospitalizations would still be 1/20 of half the maximum due to COVID. Right?

That's something I've never understood about the pandemic. Is reducing hospitalizations by a factor of 20 enough that having everyone get the virus is no longer a concern? Or was it expected that the vaccines reduce transmission enough that everyone wouldn't get it anymore? Canada has like 75% [1] (edit: oops, originally I said 85% here, but I guess that's in people 12 years and older) or higher vaccination and is still seeing record case numbers everywhere.

This isn't really an argument for or against kids in schools. I am just surprised that people are so quick to say "we have a vaccine so there's no need to worry about COVID in anyone vaccinated now". Certainly it seems like many health officials say something similar, so I must have missed something. (Or are they just trying to encourage everyone to get vaccinated? I know that many people don't really understand the details and would (erroneously) just say "it's not 100% effective so why bother")

Sources:

* "The spread of the Omicron variant of coronavirus appears to be doubling every two to three days" [0]

* "The cumulative percent of people fully vaccinated with a COVID-19 vaccine in Canada was 76.83% as of January 1, 2022." [1]

* "Fifty per cent of hospitalizations now, in Quebec, are due to people not having been vaccinated," [2]

[0]: https://www.theguardian.com/world/2021/dec/08/omicron-covid-...

[1]: https://health-infobase.canada.ca/covid-19/vaccination-cover...

[2]: https://www.cbc.ca/news/politics/duclos-mandatory-vaccinatio...

[eigenrick]

I think the issue is that public policy is based around two flawed notions that omicron has brought to light:

1. The vaccines will become decreasingly relevant, unless we can provide technology to update vaccines as quickly as they mutate. Even then, it'll be like flu vaccines. They'll help, but won't stop the spread.

2. Barring some technological breakthrough, Covid will never go away. We'll all contract it. Then it will mutate and well contact it again in the next year, and the next, forever

As such, our current policies are ineffective, and lockdown is by no means sustainable forever.

[freewilly1040]

I would add a 3rd flawed notion: that COVID is COVID, all variants are to be avoided at all costs.

At this point we've got well established indications of omicron being an unserious infection (sparing the lungs entirely, being no more than a bad cold for the vast majority of those who contract it). Not 1000% confirmed, of course ongoing study is warranted, but it would be shocking if omicron turns out to be a serious driver of illness and death.

But policy makers and media commentators are allergic to optimism on what this implies long term, so we are stuck in a state of alarm.

[axby]

> The vaccines will become decreasingly relevant, unless we can provide technology to update vaccines as quickly as they mutate. Even then, it'll be like flu vaccines. They'll help, but won't stop the spread.

Interesting, I haven't been following the pandemic as closely as I used to, but I was under the impression that the existing mRNA vaccines still work fairly well against new variants (including omicron), but that effectiveness goes down after 6 months (hence boosters). I'm not really sure if "effectiveness" is in preventing severe illness or transmission.

[eigenrick]

I'm not a virologist, but I interpret "omicron has a likelihood of 88% to escape current vaccines" as being rather ineffective. I've not found similar stats for Delta or other, but the authors of this paper seem to indicate that current vaccines aren't great against omicron.

https://pubs.acs.org/doi/10.1021/acs.jcim.1c01451#

[axby]

Thanks for the source, I've been so curious about this information but it's hard to find.

I should have said "relatively effective", since I'm also under the impression that the vaccines weren't super effective at reducing transmission of the original variant (compared to vaccines against other infections). But I also haven't seen much data, I vaguely remember hearing something from the WHO like "60% effective at reducing transmission of original variant, 40% effective against Delta", but I don't remember.

[kcplate]

The real problem is the word “vaccine”. The mRNA vaccines do not really work in a way that other vaccines do, and more importantly how we understand other vaccines to work.

Prior to this pandemic the layman understanding of a vaccine was that they generally prevented you from “contracting” the disease. You get the shot, you don’t get the disease. We were basically sold this notion for the mRNA vaccines early in 2021. However, the reality was different. Whether by way of mutation, or simply by the way the mRNA vaccines only work against a specific portion of the virus, mRNA tech seems to not be as effective at the prevention of infection but better at the prevention of severe infection. In essence, it’s not a “vaccine” as the public understood the word. However, it is a tool, and still a relevant one in diminishing the severity of the pandemic, it’s just a shame that the expectations that were set were way off.

[doktorhladnjak]

The issue isn’t with mRNA vaccines. There are conventional vaccines for COVID used in other countries like China and they’re even less effective. It seems to have more to do with respiratory viruses or coronaviruses specifically.

I also don’t know of a time in history where a vaccine was developed for an emerging disease as opposed to one that was already endemic with a lot of natural immunity around.

[axby]

TL;DR: I agree that the public thought vaccine = no more virus. But I'm not sure if traditional vaccines actually mean that you're incapable of spreading it, or even getting sick in some cases.

I agree that the public was misled as to how effective vaccines would be at preventing transmission. Especially when the CDC said that fully vaccinated people didn't need to wear masks.

But how much more effective are traditional vaccines at preventing spread of illnesses? Wikipedia pointed me to this CDC page:

> The MMR vaccine is very safe and effective. Two doses of MMR vaccine are about 97% effective at preventing measles; one dose is about 93% effective. [0]

[0]: https://www.cdc.gov/vaccines/vpd/measles/index.html

I was always under the impression that traditional vaccines were really effective, enough that the virus stops spreading eventually, but not enough that you are almost totally incapable of spreading the virus or even getting sick. Like the outbreaks in disneyland, obviously they only happened because of people being unvaccinated, but my understanding is that vaccinated people can still get sick from it. I found this Washington Post article:

> A 2015 measles outbreak linked to Disneyland led to 147 cases in multiple states as well as in Mexico and Canada. Many of those who were sickened were unvaccinated or did not know their vaccine record, according to the Centers for Disease Control and Prevention.

[1]: https://www.washingtonpost.com/health/2019/08/24/tourist-inf...

[kcplate]

I think if the covid vaccines managed to have a MMR level (90%+) preventive effect against symptomatic infection rather than 20% (I can’t find where I read that stat, it might be wrong, but I don’t think by much) against symptomatic infection, you would find less skepticism in the existing covid vaccines.

At this stage, despite being fully vaccinated and boosted, I absolutely expect to be exposed to and symptomatic from Omicron in the next 45 days.

[CogitoCogito]

What do you mean by "skepticism in the existing covid vaccines"? Are you saying that people are disapointed that the vaccines aren't better at preventing disease and spread? I'm pretty sure that everyone falls into that category. But is there anything better available? Is there any better strategy than trying to continue to improve the vaccines and do more research hoping to someday get a handle on this?

If we compare these vaccines to non-existent ones that we believe should be better, then we are disappointed. If we compare them to the possibility of having developed worse vaccines, then we would be elated.

[brandonmenc]

> Prior to this pandemic the layman understanding of a vaccine was that they generally prevented you from “contracting” the disease. You get the shot, you don’t get the disease.

afaik the flu vaccine has for decades been advertised as:

"might not always prevent, but will usually lessen symptoms"

So I'm not sure why people think this is a new thing.

[kcplate]

The flu is understood to be different, seasonal, yearly variants. It’s also why at least in the US it’s characterized as the “flu shot” as opposed to the flu “vaccine”.

Vaccines like MMR and others are understood to be generally preventative and rarely need booster if after initial doses.

Think about things that generally require boosters…they are almost always referred to by the laymen as “shots”. Nobody calls the tetnus shot a tetnus “vaccine”.

[brandonmenc]

I get what you're saying, and it makes sense, but people also often say "shots" when referring to childhood vaccines (ex: "did they get their shots yet?") They also say things like "rabies shots" and "diptet shot."

And coronavirus is also understood to be seasonal.

However, in spite of all that, I agree that the official messaging throughout this pandemic has been so inconsistent - from masking to "two weeks to flatten the curve" to "boosters" - that the public does have a right to be skeptical and exhausted.

[iggldiggl]

> I don't know much about virology but I understand exponential growth. It looks like the cases are doubling every 2 weeks (edit: I guess this might even be a few days? See [0]). In a few months, almost everyone will get it. In the last two week period, won't half the population catch it? In that case, even with 100% vaccination, hospitalizations would still be 1/20 of half the maximum due to COVID. Right?

As people become infected and gain immunity (in reality not always perfectly and not necessarily until the end of times, but on average they'll definitively do, and right now we're only talking about a simplified thought model anyway), they drop out of the pool of people available for further infections and therefore slow down the growth rate.

While still only a simplified approximation, logistic growth is therefore a better model than naive unchecked exponential growth, and the maximum case rate will be somewhat lower than "half the population gets infected in the last doubling step".

[axby]

Thanks, I actually hadn't heard of a logistic growth curve before (it looks like something I somewhat remember from high school chemistry). Can you recommend anything to read about this that apply it to the pandemic? I guess I'm beyond my math skills here. Reading normal news articles, they warn of increasing cases, but I'd like to see some raw numbers. The report they refer to is too complicated for me to understand :(

Specifically I'm wondering what the maximum number of cases in a short period is likely. I ask because I was shocked to hear that the number of ICU beds in a major city of 1M people in Canada was only a few hundred (or maybe that was total hospital beds? I can't remember). So it seems like you need to keep your "hospitalizations per population" number down to less than the ratio of "hospital beds per population".

Certainly I was wrong in saying "everyone will get it" in a few months because of the logistic growth curve, but it looks like a significant portion of the population could still be infected within the same period, even if you remove the 6% (Canada) to 20% (USA) people who have already been infected? And even if everyone is fully vaccinated, can the number of them that end up in hospital come close to the total capacity? It seems like we're already getting close to capacity.

[iggldiggl]

Sorry – while I do remember the existence of logistic growth from school, my knowledge doesn't go much beyond that, either, so I can't be of any help there.

As for your original question – I've been wondering about the same thing.

My personal back-of-the-envelope calculation was more along the lines of "If the vaccine is 90 % effective (the numbers given for Germany during the Delta wave and before the start of the third round of vaccinations were closer to 90 than to 95 %) in preventing hospitalisation and 75 % (for example) of the population are vaccinated, it means that case numbers in hospitals are 75 % x 1 + 25 % x 10 = 3.25 times higher than they would be with full vaccinations.", though I suppose there are enough holes that could be poked into that calculation, too.

A three-fold reduction in case numbers is nothing to be sneezed at, but on the other hand as long as the spread is still behaving mostly exponentially instead of turning into logistic growth and slowing down again that's only one-and-a-half doubling periods, so not that much of a buffer, either. Of course the vaccines are also somewhat (if not as well as was originally hoped) preventing some spread, so with full vaccination growth rates themselves would also be lower and hospital cases be reduced by more than threefold, but whether that's then enough, who knows?

In the end I decided there's no point in worrying myself further here, because there are too many unknown factors in getting a reasonable result that I can't easily answer and ultimately I have no desire in becoming a full-time epidemiologist.

[axby]

Other ideas as I struggle to understand the current state of affairs: maybe the vaccine is really effective at preventing transmission, but only for some period, say 1 month to 6 months after vaccination? Maybe people in Canada received their vaccines between January and June of 2021, so maybe with boosters every 6 months, transmission would be under control?

[astrange]

That's more or less it. Also

- it might be that two shots 6 months apart are more effective. i.e. skipping the 2nd shot in the 3 shot series would be fine.

- it might be that a nasal vaccine would be more effective than an injected one. We just don't have one of those yet.