To want to tear my hair out when people talk about the ‘R number’ increasing - IT DOESN’T MEAN WHAT YOU THINK IT MEANS!

[GinFling]

I am SO sick of everyone having a hot take on this virus - from friends and colleagues, and especially the media. Article after article about how the R value is increasing, nearly over 1, etc etc, and how this means we are heading for a second wave/disaster/the sky falling in. No, it is more complex and nuanced than that, and in fact it’s harder and harder to have a low R as the virus gets less prevalent. It is also hugely skewed by local outbreaks - such as in care homes and hospitals.

These two articles are quite helpful in understanding it:
www.bbc.co.uk/news/amp/health-52944037
unherd.com/2020/05/what-the-headline-covid-figures-dont-tell-you/

I wish everyone would just STOP using R to pretend to know what they’re talking about. We’re not all statisticians or virologists, for good reason.

[mocktail]

I've found an article that explains it well. //www.wired.co.uk/article/coronavirus-r-number-uk

If the R is higher than one then that means that a disease will keep on spreading to more and more people. Imagine that coronavirus had a R of two. That would mean that every person with the disease would go on to infect two new people. So if you started with 100 infected people, they would infect 200 people who would then go on to infect 400 people.

Even if the R was a lot lower – say 1.2 – the disease would still move through a population really quickly. Those 100 infected people would infect 120 people, who would then infect 144, then 173, then 208. In just four rounds of transmission, the number of people each time would double. Mathematicians call this phenomenon exponential growth, and it explains why coronavirus infected so many people all over the world so quickly.

[LarryTheLurker]

R0 is no better than guesswork. It is not real data.

[mocktail]

@scaevola surely if the R rate is above 1 at all (even 1.1) there will be exponential growth? It would be an upward curve, not linear.

[HesterShaw1]

After one there is a growth in infections, and after two the growth is exponential.

[Namenic]

Scaevola - I thought that if a single infected person passes it onto more than one other person on average during the course of the disease, mathematically the growth would be exponential (though not necessarily rapid?)?

I guess there are lots of different definitions of R.

[winniestone37]

This has been a good thread I understand more though never talk has if I’m an expert just a human gathering information.

[HesterShaw1]

*accurate not acute


And the "lowest common denominator" comment isn't meant as an insult to make people indignant.

[HesterShaw1]

Why complicate things?

Because it IS complicated! There are many ways we should be assessing the situation not just stubbornly using a single figure which may or may not be acute just so the lowest common denominator thinks that they understand it! If we go on this bloody R number only we could remain under restrictions unnecessarily.

[scaevola]

"Am I wrong if I think that if the R rate is above 1 consistently, then the number of infected people is growing and will grow at an exponential (but not necessarily rapid) rate?"

If the R0 is 2 or more, the growth will be exponential

As I noted much earlier in the thread, R0 assumes a population where everyone is vulnerable.

How an outbreak progresses also depends on how mant people are immune. So if under 20% have antibodies, as one survey showed for
London (with even lower figures elsewhere) then we could yet see a high R, whether 0 or e, and 0 still useful concept in largely unexposed populations.

The two types of R figures are of course related - which is why the R of measles becomes a concern only when the number the number of immune people in the population falls. It's why we think of it as a disease of childhood - it's because the aduits (bar very few) all had it as children and the survivors were lifelong immune. Only when enough new people had been born did the odd cluster of case become a full on outbreak amongst the vulnerable - where the R was up in the teens (probably) but the effect beyond tat minimal (it will,of course be different if measles breaks through, as the over 50s will be unaffected, the unimmunised DC born from about 1996 (single vax license lapsed for admin reason in 1997) until the body of evidence refuting Wakefield was amassed. My guess is that many of those DC never has catch ups and so there is a pool of people in their early twenties who are vulnerable. The same population as mumps seems to strike these days.

[Pixxie7]

Why complicate things most people have a basic understanding that if the R rate rises the risk of infection rises.

[Namenic]

Am I wrong if I think that if the R rate is above 1 consistently, then the number of infected people is growing and will grow at an exponential (but not necessarily rapid) rate?

OP - is what you are saying that the weekly R can fluctuate (sometimes above 1) but overall infections go down? Surely for this to happen, the trend over weeks must include a fair number of weeks where R is below 1?

OP - Risk for different people is different. Also, assessment of additional risk also depends on how much you think you can do about it. If you believe something is unavoidable, even if the risk is large, I guess more people are likely to accept it. I think this may have been one of the problems with UK’s corona strategy initially. If we do not know about how this will play out, isn’t it better to be cautious?

[Teateaandmoretea]

In terms of herd immunity no one knows how immunity works with covid yet and it is possible there is more than one immune response. Just because people don’t test positive for that set antibody response does not mean they will catch it again. No one knows the extent of asymptomatic transmission either which is a key part of it.

It’s the problem with science right now, evidence is needed to find answers.

[syskywalker]

Also herd immunity can NOT be achieved with a Virus, where over 70% of infected do Not develop antibodies!

[syskywalker]

And no one mentions how the real infection and death rate due to covid is being manipulated so any R-rate prevalence or not is incorrect.

[HesterShaw1]

I'm a scientist and so's my wife

[masterblaster]

@KrisAkabusi

Actually, I'm a scientist and it does mean what I think it means.

I am also a scientist, and it also means what I think it means.

[KatySun]

Well, the virus might not kill you but three months on, I still have fairly debilitating symptoms and am nowhere near full health. It is not like a nasty ‘flu. I have no underlying health conditions. My health has been wrecked.

So whatever the discussion about the R number, please do not feed into the myth that this is a mild illness unless you are in hospital. There is enough evidence emerging that for many people it is not.

[NoIDontWatchLoveIsland]

Yanbu OP but mn is a hive of excessively paranoid people who will only believe the worst and who are unable to process the low risk posed by covid19 to most of us.

[FelicisNox]

I couldn't give a shiny shite about (media) R rates.... I go by what I see at work (hospital) and local infection/death rates.

YANBU to be yelling at everyone: it's not your job to be "correcting" everyone.

Move along.

[Localocal]

I think people do understand the r value quite accurately. It's not a complicated concept. They may overestimate it's importance, but then they have SAGE scientists (though apparently not every single person on Mumsnet) telling them it's important, so I think they can be forgiven for thinking it matters.

I think people who are following news of the r rate are also probably following prevalence and death rates, so they are probably better informed and less stupid than you think.

Also, to add a third example to your two:

R rate of 1.5, prevalence of 10. That low prevalence of 10 is going to be 250 in 8 transmission cycles. It does matter.

Maybe experts should explain that r is unlikely to keep dropping as the virus peters out and that that's ok. But there will be plenty of time for that to be clarified when we get there.

In the meantime, take a deep breath and accept that not everyone is a doctor, but everyone is affected by this virus. So they will have views. If you genuinely want to help shape those views, how about not headlining your efforts with wanting to tear your hair out at how stupid they are?

Pro tip: people are more likely to listen and learn if you don't act like an asshole to them right from the start.

Unless you aren't trying to educate anyone and are just trying to show off your intellectual superiority? In which case, here's another pro tip: caps lock and exclamation marks do not inspire confidence in your wisdom.

[Khione]

I agree with you in principle Op, but insulting people#s intelligence usually serves to make them more intransigent.

On the other hand - those that do understand it - and are still worrying about minor regional variances - are the ones that worry me.

[0v9c99f9g9d939d9f9g9h8h]

I think anyone at this stage extolling the virtues of herd immunity, knowing how many will not survive that, has a peculiar thirst for eugenics.

[Noextremes2017]

'Not rude just honest' - if you read the whole thread the discussion is about, among other things, the changing significance of R as the infection rate falls; how it is skewed by the effect of high R in Hospitals / nursing homes etc; and how averaging it across vast areas of the country is pretty meaningless.

Yes we can all do the maths but the bare statistical answer means different things in different contexts.

[Cutesbabasmummy]

Op you get the award for the most patronising post of last week.

[SurroundedByIdiotsEverywhere]

If you are unable to understand the 'R' rate after all this time you never will.

They cannot be any clearer and it is simply out of your mental capabilities to understand it.

Not being rude, just honest!