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R value - what does it mean?

(19 Posts)
Fennel Fri 12-Jun-20 17:17:17

The media seem to be making a lot out of this at the moment. I don't understand what it means.
Some proof of the decline of the power of the virus?
Does anyone know?

Tabbycat Fri 12-Jun-20 17:25:04

I think it means the reproduction number and is a way of rating a disease's ability to spread.

It's the number of people that one infected person will pass the virus on to, on average. So if it is over 1 the virus is still spreading and if it's less than 1 it's slowing down.

pensionpat Fri 12-Jun-20 17:33:42

If the R figure were 2, the number of infections would be 4, then 8, then 16, then 32. Doubling up to high figures very quickly.

Sardinia2020 Fri 12-Jun-20 17:37:26

If the R remains below 1 then it means that each infected person is passing the disease onto fewer than one person which is good.

Fennel Fri 12-Jun-20 17:45:03

So less than one, it could either be because of the effects of lockdown, or the virus is losing its power?
or other things.

BlueSky Fri 12-Jun-20 17:55:03

I'm afraid I'm rather pessimistic on this, I believe the R value is low because of the effects of lockdown. Would like to believe it was because of the virus losing its power but I very much doubt it, not yet anyway.

varian Fri 12-Jun-20 17:55:16

The problem is that although the R value may be on average, just below 1, it varies in different parts of the country. In some regions it is certainly still above 1 and so it is very dangerous for the lockdown to be relaxed everywhere right now.

MawB Fri 12-Jun-20 18:15:24

I don’t think there is any actual medical evidence that the virus is weakening . It may be mutating but it could as easily be getting stronger.
It is the spread which makes the difference. Fewer people who are positive infecting even fewer people who in turn infect even fewer people is the way forward.
The virus exists for one purpose - to reproduce itself. No positive cases? >No host for the virus.> Virus dies out.

Fennel Fri 12-Jun-20 18:54:59

That's what I was thinking MawB.
The virus is a living creature, looking for means to reproduce.
If we deprive it of means to live it will die - or mutate and adapt to other means of survival. God forbid.
I think most of us underestimate the implications.
Look what has happened to the resistance of bacteria to antibiotics.
Sorry to be so depressing.

rockgran Fri 12-Jun-20 19:20:35

I don't think the virus is alive as such -it is more like a poison. It becomes active when it has a host. Without a host it decays. If we could stop passing it around it might just disappear.

growstuff Fri 12-Jun-20 19:58:03

Viruses don't behave in the same way as bacteria.

They're not alive and need a host. In the case of coronavirus, the host is ACE2.

If people were strict about social distancing, it would not be able to spread.

I agree with you rockgran.

fevertree Fri 12-Jun-20 22:06:42

"If the R remains below 1, that means fewer than one person is being infected "... how does that work, does half a person get infected? smile

Bathsheba Fri 12-Jun-20 22:38:48

fevertree grin

growstuff Sat 13-Jun-20 01:40:43

If the R is 0.5, it means that, on average, two people will infect one person. One person transmits the infection, while the other one is isolated quickly enough not to pass on the infection.

FarNorth Sat 13-Jun-20 04:22:01

Surely the whole point of lockdown was to hinder the spread of infection, thus lowering the R number - the rate of its spreading.
Having done that, we shouldn't be too hasty about getting unlocked again, imo.

varian Sat 13-Jun-20 11:48:19

As any relaxation of the lockdown will inevitably lead to a rise in R, there should be no relaxation until R is at 0.5 or thereabouts. Relaxation measures should be introduced gradually and the effect of each measure monitored.

If we had a second wave of infection, it is unlikely that the public would be so co-operative about lockdown as we were, at least until the Cummings scandal.

Alexa Sat 13-Jun-20 12:03:43

"I don't think the virus is alive as such -it is more like a poison. It becomes active when it has a host. Without a host it decays. If we could stop passing it around it might just disappear."

I like the analogy with poison! Unlike mice that have baby mice, or bacteria that split themselves up into more bacteria, virus uses virally "poisoned" cells from a host to multiply.

Alexa Sat 13-Jun-20 12:05:06

PS I quoted Rockgran

rockgran Sat 13-Jun-20 13:46:20

Thanks, Alexa.