Coronavirus - General Chat - No statistics

[XFool]

Measles is a horribly infectious disease. If it arrived on these shores for the first time this year and killed multiple 1,000s and the long-measles version caused significant blindness I am sure society would be throwing multiple billions of pounds at locking down and developing a vaccine. Similar to Covid. But years down the line when it is endemic but only affecting a few, rightly more time and effort is spent on trying to cure cancer, for example. Or the prevention of those "steady state" road deaths.

The existence of the infectious nature of measles, or the non-linear potential of it, hasn't changed

Yes it has. Many people will have immunity to measles, nowadays due to widespread childhood vaccination. Leading to effective 'herd immunity', so long as people like Andrew Wakefield or his supporters don't intervene.

- yet the swing from "measles" to "road death" as a societal concern will occur. At some point the same will be true of Covid.

Of course! That is equally obvious. Let us hope that transition is managed by attending to the known facts, rather than any populist, political pressure.

[1nvest]

Current rates are of the order 20,000/day contractions, 20/day deaths (0.1%)

Do you think that possibly the low numbers are due to the vaccine?

Perhaps not. If Covid is fatal for 0.3% of the population then those more inclined to die from contraction may have already passed. My 89 year old mother contracted Covid back in January and didn't even have any snivels (great anxiety for me, especially after the two week period when it was suggested as being more likely to flare up - only to see nothing).

Vaccines don't remove the risk of contracting it, but do alleviate the condition for the relatively small number/percentage for which it can be a life threatening thing. Would have been better to identify why some are at greater risk and only vaccinate those that match that profile.

UK lockdown was pathetic. Millions were still flying in/out and travelling around. Ask people to self isolate and they wont etc. Only selected workers were paid to stay at home, many others received little if any support. Sweden that had no lockdown and has 1/7th the population of the UK has see 15K death, so 105K proportioned to UK population size, perhaps because they were less inclined to export Covid into care homes where more are at risk of contraction being fatal, or perhaps where they better supported their care homes rather than expecting them to DIY PPE out of garden shoe covers and bin-liners as was the case in the UK.

[XFool]

Um...

UK scientists caution that lifting of Covid rules is like building ‘variant factories’

The Guardian

Experts react with dismay to ‘frightening’ attitude of Sajid Javid towards removing protections

“Above all, it is frightening to have a ‘health’ secretary who wants to make all protections a matter of personal choice when the key message of the pandemic is “this isn’t an ‘I’ thing, it’s a ‘we’ thing.”

[redsturgeon]

Sweden that had no lockdown and has 1/7th the population of the UK has see 15K death, so 105K proportioned to UK population size, perhaps because they were less inclined to export Covid into care homes where more are at risk of contraction being fatal, or perhaps where they better supported their care homes rather than expecting them to DIY PPE out of garden shoe covers and bin-liners as was the case in the UK.

You might like to compare Sweden's deaths with its neighbours who did lockdown...it does not look good.

You also clearly have not read about the care home scandal in Sweden where half of its death came from.

John

[onthemove]

Sweden that had no lockdown and has 1/7th the population of the UK has see 15K death, so 105K proportioned to UK population size, perhaps because they were less inclined to export Covid into care homes where more are at risk of contraction being fatal...

If it weren't for their care home issues, Sweden's death rate from Covid would be significantly lower...

"Coronavirus: What's going wrong in Sweden's care homes? Care home residents account for nearly half of deaths linked to Covid-19 in Sweden . Some healthcare workers believe an institutional reluctance to admit patients to hospital is costing lives...." https://www.bbc.co.uk/news/world-europe-52704836

It's unfortunate, because outside of care homes, Sweden was potentially a good example of a strategy of respecting the population, and treating people as adults, and it's unfortunate that their care home mistakes - which they acknowledge - spoil the numbers somewhat.

In contrast to Brazil, and US (Trump), Sweden didn't try to downplay or dismiss covid, instead Sweden put the scientists at the front of government briefings, and let the scientists advise the public.

I mean, just look at the UK at the moment.. we see a handful of scientists whining at the government that the government mustn't release restrictions.

IMV, these scientists have it all wrong. Why do they need to go through government? If the scientists are confident in their science, there's nothing stopping them going public and addressing the public directly. You don't have to have laws to mandate how people behave.

It's almost like a large portion of the UK public deliberately want to follow a government getting it wrong, so that they can then blame the government.

At the end of the day, the pandemic is about society, not the government. It's about people's behaviour and how it affects the people. I believe Sweden had the right idea - the pandemic is about people, so let the people choose where they want to strike the balance.

Just be sure to give them the best objective facts available at the time, and don't do a Trump.

[1nvest]

Plus there is the 'tragedy of the commons' effect, where individuals act in their own self-interest against the common good.

Applies to the house of Lords also

When a government is in power with just 20% of the population having voted for their party, the majority have little trust in such government, 8 out of 10 DIDN'T vote for it. The largest majority are those who can't be bothered to vote, have no faith in the corrupt, liars and thieves that the houses of Parliament often are revealed to be.

That reflects through to trust/faith in the vaccines. When the liars say to stay at home but do otherwise themselves etc. then naturally when they say its best to take the vaccine many might hesitate/decline.

[1nvest]

At the end of the day, the pandemic is about society, not the government. It's about people's behaviour and how it affects the people.

For a large proportion of the people contracting Covid is a minor factor, yet that body have had to sacrifice 100 million person years to accommodate a small proportion of the population for whom contracting Covid is a issue. Many in that larger group are likely now in the 'drop dead' category feeling that they've already had to make too great sacrifices. Enforcement only further agitates - have the vaccine or lose your job or not be permitted to holiday etc. discrimination. All driven by a government/party that they more likely didn't vote for anyway. The blame as ever largely lies with Parliament, a entity that more often is managing crises of its own making and repeatedly demonstrates that it is a liability not a asset.

[Mike4]

On the other hand, people who CBA to vote have no democratic right to complain about the government they get landed with.

[XFool]

If it weren't for their care home issues, Sweden's death rate from Covid would be significantly lower...

Ah. If it weren't for the bad news all the news would be good!

In contrast to Brazil, and US (Trump), Sweden didn't try to downplay or dismiss covid, instead Sweden put the scientists at the front of government briefings, and let the scientists advise the public.

Yet below, you think they "have it all wrong" and object to their "whining".

I mean, just look at the UK at the moment.. we see a handful of scientists whining at the government that the government mustn't release restrictions.

I really don't know what the current SAGE etc. consensus is on this but, if they were mainly saying that I'd be worried rather than complaining about them "whining". Do we really need a more Trump approach? Shoot the messenger - "Stop testing so much then there won't be so many cases"

...these scientists have it all wrong. Why do they need to go through government? If the scientists are confident in their science, there's nothing stopping them going public and addressing the public directly. You don't have to have laws to mandate how people behave.

Lots of people not infrequently think various scientists "have it all wrong". e.g. Climate change deniers. Also, my bet is that, on SAGE, they are bound by legal rules and would be kicked off SAGE if they went public. Whatever happened to that Chief Nurse who once spoke her mind at the government briefing? She was never seen or heard from again!

But, if it's scientific opinion not bound by SAGE restrictions you want: https://www.independentsage.org

At the end of the day, the pandemic is about society, not the government. It's about people's behaviour and how it affects the people. I believe Sweden had the right idea - the pandemic is about people, so let the people choose where they want to strike the balance.

One person one vote? The trouble with that, in a pandemic, is the people are definitely not all equal. Then again - there is the well known problem termed 'The tragedy of the commons'. In this case that meant, for one thing, the fate of the NHS.

[murraypaul]

Current rates are of the order 20,000/day contractions, 20/day deaths (0.1%)

Do you think that possibly the low numbers are due to the vaccine?

Perhaps not. If Covid is fatal for 0.3% of the population then those more inclined to die from contraction may have already passed. My 89 year old mother contracted Covid back in January and didn't even have any snivels (great anxiety for me, especially after the two week period when it was suggested as being more likely to flare up - only to see nothing).

Vaccines don't remove the risk of contracting it, but do alleviate the condition for the relatively small number/percentage for which it can be a life threatening thing. Would have been better to identify why some are at greater risk and only vaccinate those that match that profile.

Vaccines do reduce the risk of contracting it.
And we have no idea why some are at greater risk than others (outside of the obvious like age), so we still wouldn't have vaccinated anyone yet.
We identified those at greater risk by blunt principle of age, and vaccinated them first, then working down the risk profile.
Which age group would you suggest we decide not to vaccinate?
Currently a greater proportion of deaths among 40-59 years old are related to covid than for any other age group, including 80+.

Sweden that had no lockdown and has 1/7th the population of the UK has see 15K death, so 105K proportioned to UK population size, perhaps because they were less inclined to export Covid into care homes where more are at risk of contraction being fatal, or perhaps where they better supported their care homes rather than expecting them to DIY PPE out of garden shoe covers and bin-liners as was the case in the UK.

Or perhaps because they only have 9% of the population density of the UK.

[murraypaul]

That reflects through to trust/faith in the vaccines. When the liars say to stay at home but do otherwise themselves etc. then naturally when they say its best to take the vaccine many might hesitate/decline.

Many are not hesitating or decline. A very small minority are.

https://www.ons.gov.uk/peoplepopulation ... 20june2021

In the latest period, 26 May to 20 June 2021, based on adults in Great Britain, we found:

- More than 9 in 10 (96%) adults reported positive sentiment towards a coronavirus (COVID-19) vaccine, while 4% reported vaccine hesitancy.

[onthemove]

Ah. If it weren't for the bad news all the news would be good!

You can be flippant all you like, if you don't want to engage with the evidence.

But in terms of evaluating whether allowing the population of Sweden freedom to adapt their behaviour as they deem appropriate in light of the evidence, it would seem appropriate to omit the deaths caused by a direct government policy that determined whether or not to admit care home covid patients to hospital.

It wasn't the patients making that choice. Nor was it the patients' families. It was the official policy that led to that...

"They told us that we shouldn't send anyone to the hospital, even if they may be 65 and have many years to live. We were told not to send them in, https://www.bbc.co.uk/news/world-europe-52704836"

So it makes sense to omit these deaths when evaluating lockdowns vs no lockdowns; those deaths are clearly not due to any absence of a mandatory lockdown strategy.

Yet below, you think they "have it all wrong" and object to their "whining".

You misunderstand. I wasn't saying the scientists have their science wrong. I was saying they have their strategy of trying to convince the government wrong.

The government doesn't matter. What matters is how people behave.

The scientists can stop whining about the government not taking any notice, and simply go direct to the people - that's the people who they want to change their [the people's] behaviour.

We have freedom of speech in this country. The scientists can speak their mind to the public if they want.

The press certainly seems happy to report other scientists views, so it's not like they are being suppressed.

I suspect the issue is though, that not all scientists agree. But that in itself, I would argue, is also reason to let the public make up their own mind, rather than relying on a single person or small group of people (Boris, etc) trying to make a judgement.

Do we really need a more Trump approach? Shoot the messenger - "Stop testing so much then there won't be so many cases"

Who said anything about needing the Trump approach - I contrasted against the Trump approach.

The Swedish government didn't attempt to deny covid the way Trump did. They are in no way comparable. There was no 'false' news from the government in Sweden. The Swedish people were given the facts, and they were not downplayed. The swedish government gave the scientists center stage.

Quite the opposite of Trump.

Trumps strategy is a completely different strategy to what Sweden followed.

The two are in no way comparable.

Attempts to conflate the two, could be seen as trying to distract from the evidence from Sweden.

Much like trying to include deaths from care homes that had no relation to the lockdown / no lockdown policy outside of care homes.

There's an interesting article here, from early in the pandmic, that explores the issue of the different approach in Sweden..

"On the face of it little has shut down. But data suggests the vast majority of the [Swedish] population have taken to voluntary social distancing, which is the crux of Sweden's strategy to slow the spread of the virus.

Usage of public transport has dropped significantly, large numbers are working from home, and most refrained from travelling over the Easter weekend. https://www.bbc.co.uk/news/world-europe-52395866 "

Certainly early on, people in Sweden were making the behavioural changes necessary, without the need for compulsion.

And a central tenet of the Swedish idea, was recognising early on, that the behavioural changes would likely need to last longer than the 12 weeks we were being told with the UK lockdown. And they figured that you would more likely get longer term respect for the behavioural changes needed, if you allow people to voluntarily make the changes, rather than force them - carrot rather than stick.

[Mike4]

That reflects through to trust/faith in the vaccines. When the liars say to stay at home but do otherwise themselves etc. then naturally when they say its best to take the vaccine many might hesitate/decline.

Many are not hesitating or decline. A very small minority are.

https://www.ons.gov.uk/peoplepopulation ... 20june2021

In the latest period, 26 May to 20 June 2021, based on adults in Great Britain, we found:

- More than 9 in 10 (96%) adults reported positive sentiment towards a coronavirus (COVID-19) vaccine, while 4% reported vaccine hesitancy.

And yet the proportion of the whole population fully vaccinated remains surprisingly small. Approx 50% so far.

The BBC on Saturday said 63% of adults (over 18) so far have been vaccinated with two doses, which is (near as dammit) only 50% of the whole population.

Another thing the gov't persists in talking about is the number of people offered the vaccine. A pointless statistic which seems to imply they think offering someone a vaccine but them refusing it is just as effective as vaccinating them.


Edit to clarify the 'two doses' point.

[XFool]

And a central tenet of the Swedish idea, was recognising early on, that the behavioural changes would likely need to last longer than the 12 weeks we were being told with the UK lockdown. And they figured that you would more likely get longer term respect for the behavioural changes needed, if you allow people to voluntarily make the changes, rather than force them - carrot rather than stick.

And yet, when it came to it, the various UK lockdowns were widely supported by the population. The man in charge of the situation in Sweden himself said that it wasn't for him to say what was the best approach for other nations, they would decide for themselves, his job was to organise the response in Sweden.

BTW. Don't think there has not been criticism of the Swedish approach, from within Sweden.

https://en.wikipedia.org/wiki/COVID-19_pandemic_in_Sweden#Social_impact

"The Swedish government's approach has received considerable criticism. Some Swedish scientists had called for stricter preventative measures throughout the pandemic, and an independent commission (Coronakommissionen) found that Sweden failed to protect care home residents due to the overall spread of the virus in society. In December 2020 both King Carl XVI Gustaf and Prime Minister Stefan Löfven admitted they felt that Sweden's COVID-19 strategy had been a failure due to the large number of deaths."

[onthemove]

And yet, when it came to it, the various UK lockdowns were widely supported by the population. The man in charge of the situation in Sweden himself said that it wasn't for him to say what was the best approach for other nations, they would decide for themselves, his job was to organise the response in Sweden.

BTW. Don't think there has not been criticism of the Swedish approach, from within Sweden.

https://en.wikipedia.org/wiki/COVID-19_pandemic_in_Sweden#Social_impact

"The Swedish government's approach has received considerable criticism. ... an independent commission (Coronakommissionen) found that Sweden failed to protect care home residents due to the overall spread of the virus in society. In December 2020 both King Carl XVI Gustaf and Prime Minister Stefan Löfven admitted they felt that Sweden's COVID-19 strategy had been a failure due to the large number of deaths."

It's not a great example to use though against general lockdowns.

The UK both locked down care homes, and also locked down the wider population.

Sweden could have protected care home residents by locking down care homes like the UK did - no visitors - without needing the wider population under any UK style mandatory lockdown.

The question which your quote doesn't answer is what the death rate outside of care homes was.

That same article points out...

"Sweden has several times the number of confirmed cases and deaths of all neighboring Scandinavian countries; but several other European countries have higher rates of confirmed cases and deaths per capita than Sweden. Close to half of those who died had been living at nursing homes"

That's not exactly strong evidence that mandatory lockdowns were strictly necessary, as opposed to instead using voluntary measures and guidelines.

When you take into account how hard lockdown will have been for many, you would really hope that it would have made a more substantial difference than appears to be the case.

I mean, I was reasonably lucky, I'm in a flat with separate living room and bedroom, overlooking a nice neighbouring garden with trees and birds, and such. So quite pleasant while working from home. But a number of the other flats in the same building, studio flats with just a single small room doubling up as living room and bedroom, and a tiny bathroom and small kitchen, are low down (ground floor), no sunlight and only look out at a brick wall. I can't imagine what those residents felt only being allowed out of that for max 1hr exercise per day for 12 weeks. From what I can tell, I think most have now moved out at the first opportunity, and who could blame them.

The evidence from China early on was that transmission was not likely outside...

" https://www.sciencemediacentre.org/expe ... -outdoors/
““It is more difficult to study outdoor virus transmission but this epidemiological analysis of >300 transmission events from China during their earlier COVID-19 pandemic only found one case of outdoor transmission:

https://onlinelibrary.wiley.com/doi/ful ... /ina.12766

“It says: ‘Our study does not rule out outdoor transmission of the virus. However, among our 7324 identified cases in China with sufficient descriptions, only one outdoor outbreak involving two cases occurred in a village in Shangqiu, Henan. A 27‐year‐old man had a conversation outdoors with an individual who had returned from Wuhan on January 25 and had symptom onset on February 1. This outbreak involved only two cases.’"

And the evidence from Bournemouth beach is that there was no significant outdoor transmission...

https://www.bbc.co.uk/news/53519668
"Did Bournemouth beach crowds spread coronavirus? ... Was there a spike in cases?
One month on, the statistics do not suggest a significant spike in coronavirus cases."

So I struggle to see how locking my neighbours up in their studio flats, without sunlight or any meaningful space to move, for 23 hrs a day for 12 weeks, only letting them out for 1hr exercise per day, can at all be considered proportionate or reasonable.

[murraypaul]

That reflects through to trust/faith in the vaccines. When the liars say to stay at home but do otherwise themselves etc. then naturally when they say its best to take the vaccine many might hesitate/decline.

Many are not hesitating or decline. A very small minority are.
https://www.ons.gov.uk/peoplepopulation ... 20june2021

In the latest period, 26 May to 20 June 2021, based on adults in Great Britain, we found:
- More than 9 in 10 (96%) adults reported positive sentiment towards a coronavirus (COVID-19) vaccine, while 4% reported vaccine hesitancy.

And yet the proportion of the whole population fully vaccinated remains surprisingly small. Approx 50% so far.

The BBC on Saturday said 63% of adults (over 18) so far have been vaccinated with two doses, which is (near as dammit) only 50% of the whole population.

We aren't vaccinating the whole population, we are only vaccinating adults, so the 50% is an irrelevant figure.
Our two-dose vaccination rates will be lower because we delayed the second dose to cover more people with a first dose.

And even with that, both our first and second dose vaccination rates are higher than the US, France, Germany, Italy, Spain, Ireland, the Netherlands, Belgium, ...

So when you say 63% is surprising small, compared to who?

[swill453]

We aren't vaccinating the whole population, we are only vaccinating adults, so the 50% is an irrelevant figure.

It's very relevant, when referring to the oft-mentioned "herd immunity", where something like 70% of the entire population has to have some level of immunity.

If we're not going to vaccinate under-18s then getting to even 100% of adults may not be enough.

Scott.

[gryffron]

We aren't vaccinating the whole population, we are only vaccinating adults, so the 50% is an irrelevant figure.

It's very relevant, when referring to the oft-mentioned "herd immunity", where something like 70% of the entire population has to have some level of immunity.
If we're not going to vaccinate under-18s then getting to even 100% of adults may not be enough.

But children are largely immune to the effects of covid anyway. Even without vaccination they suffer about the same as a vaccinated adult.

Gryff

[servodude]

We aren't vaccinating the whole population, we are only vaccinating adults, so the 50% is an irrelevant figure.

It's very relevant, when referring to the oft-mentioned "herd immunity", where something like 70% of the entire population has to have some level of immunity.
If we're not going to vaccinate under-18s then getting to even 100% of adults may not be enough.

But children are largely immune to the effects of covid anyway. Even without vaccination they suffer about the same as a vaccinated adult.

Gryff

Yes.
But "herd immunity" is, or was, normally about the level of immunity from infection at which the spread ceases being able to grow
- it's how a community protects those who cannot be vaccinated

Without immunity from infection the young defeat that goal as they form a reservoir, and vector for spread

Hopefully it will not matter other than as semantic pedantry
-sd

[Julian]

We aren't vaccinating the whole population, we are only vaccinating adults, so the 50% is an irrelevant figure.

It's very relevant, when referring to the oft-mentioned "herd immunity", where something like 70% of the entire population has to have some level of immunity.

If we're not going to vaccinate under-18s then getting to even 100% of adults may not be enough.

Scott.

I've been thinking about this (assumed) 19th July unlock and, while this might well be a case of me shoe-horning my own rationalisation onto the situation, I really have been wondering whether the issue being debated above is actually quite core to the governments thinking re the 19 July strategy.

I've also heard 80% mentioned a lot to get to herd immunity(*) so I'll split the difference and go with 75% (same footnote caveat). As has been observed we are only vaccinating the over 18s at the moment so with the lack of vaccination for the under 18s plus all of the adult refuseniks plus those genuinely unable to take the vaccine for health reasons, access reasons, or maybe needing many more months to get over hesitancy due to concerns about side effects I don't think the vaccination program as conceived now will get us there.

The government (HMG) is currently sounding cautious about vaccinating under 18s. It came up in the press briefings yesterday. No vaccines are approved for the under 18s in the UK at the moment (although they are administered off label to under 18s in certain circumstances at the discretion of medical professionals). HMG is looking at safety data from other countries who are vaccinating under 18s as part of their general rollout and approval might yet be sought but that will take time (Chris Whitty said yesterday the approval for under 18s is tricky because the risk/benefit discussion is more finely balanced) and the next stage of actually rolling out the vaccine to the under 18s if it was approved might get some pushback from certain sectors of the public plus it might coincide with wanting to give booster shots to the most vulnerable.

So what to do?

Well, maybe in effect 19th July could be seen as HMG starting its mass vaccination program for the under 18s using the only "vaccine" it currently has available to it - natural infection. The virus has already been circulating strongly in the under 18s but presumably with all restrictions removed, including stuff such as music festivals etc open, the rate of spread in the under 18s might increase. I also note the announcement today about the removal of requirements next month for under 18s to self-isolate if they have come into contact with an infected person. Again, this should increase transmission amongst the young. We also shouldn't forget the young adults in maybe the 18 - 24 year age group and even the 2 or 3 5-year age bands above that. Vaccine uptake amongst those lower age groups seems to be plateauing at a much lower level than for older people, it might end up well below 75% uptake, so opening up nightclubs and packing pubs more densely will presumably allow the virus to get to more of those younger unvaccinated people.

So maybe this is the overall strategy. Give the more vulnerable section of the population their immunity via vaccines so that you don't get a load of people dying along the way as collateral damage if the virus had been allowed to let rip before the vaccines were available and then, once the vaccines have not only given that section of the community immunity but also pretty good protection against all of severe illness, hospitalisation and death, then allow or even actively enable the less vulnerable section of the population to get their immunity via natural infection.

The big risk in the strategy is will the vaccine protection remain as strong as hoped for the more at risk (and as a healthy 62 year old I still count myself in that category) once the virus becomes prevalent, and also will the incidence of severe illness and above remain acceptably low amongst the young as the virus seeks out all the unvaccinated amongst them?

If those risks pay off I think this actually gets us to a good outcome, and in "us" I include those still clinically vulnerable but not able to be vaccinated because it might well enable them to get back to a more normal life sometime in the next few months. Had we continued to keep restrictions in place to halt the spread of the virus then, in the absence of a well-taken up vaccination program for the under 18s and strong take-up with all other age groups, once restrictions were lifted let's say even next spring, those vulnerable people would have come into a world where a fair number of the under-18s and even a lot of the young adults might still not have immunity from either vaccination or natural infection and so would still be a potent transmission path within the community thus putting those vulnerable people at risk as soon as they started to start trying to live a normal life. Chris Whitty even sort of alluded to that (I think) in yesterday's press conference when he said that there are some lockdowns that could reduce deaths and some that would only defer them and that continuing the lock down over this summer was likely to only defer deaths until the winter rather than actually save lives.

Like I said up front, maybe this is me imposing my own rationalisation onto things to come up with a strategy but if this is indeed the conscious strategy at play here, and as long as the risks don't back fire, then I actually think it's a pretty good one just on the health considerations alone without even considering the economic benefits of a full unlock on (we hope) 19th July.

- Julian

(*) It seems to me that it's meaningless to quote a specific figure for herd immunity in isolation. 70% of the population with immunity from vaccines? Is that 70% regardless of whether those people were vaccinated with a vaccine that offers 50% protection against the prevalent strain vs one that offers 95% protection? I would say clearly not. Any figure for what percentage of the population needs to have immunity in order to reach overall herd immunity must surely be a function of the level of immunity in that percentage of the population with immunity? And the level of immunity isn't a constant across that group of people with immunity either, people will have had different vaccines with different efficacy characteristics and others will have acquired their immunity via natural infection. And it is not only the levels of efficacy but potentially immunity from different sources will have different decay characteristics. So essentially any figure bandied about, e.g. 80%, must be in the context of an assumed immunity profile for those with immunity i.e. that figure is in fact a function of a given immunity (efficacy) profile where that immunity profile is in itself an extremely complex variable (not in the sqrt(-1) sense!). I assume it's also affected by the transmission properties of a particular virus so is also specific to a specific virus. The simple percentage numbers we see all over the place must, I think, hide an extremely complex calculation that epidemiologists are presumably doing in the background that we don't get to see.