The viability of social distancing, and confusion over whether it should be 1m or 2m

[DerekC]

I heard Boris Johnson announce, with lots of trumpeting, the change of social distance from two metres to "one metre plus" from 4th July. But that isn't what the government guidelines say, if I am reading them right. I am responsible for doing the risk assessment for the reopening of our local community hall, so I am looking at them rather carefully. Of course the guidelines for community buildings haven't been issued yet (silly of me to look for them really) so I have looked at the ones for pubs and restaurants instead. What they say is " 2m, or 1m with risk mitigation where 2m is not viable, is acceptable - you should consider and set out the mitigations you will introduce in your risk assessments". So it's 2m, unless you can show that 1m is not viable for your business or organisation in which case you have to mitigate the risk of the closer distance.

And of course, encouraged by the media, people are already interpreting that as one metre plus or minus a bit.

If I am right in my reading of the guidelines, isn't this the most dangerous Johnson fudge yet? It would appear to have been done so that he can make a big announcement which sounds good whilst keeping the scientific advisors onside by writing guidelines which convey a different message if you read them carefully.

 

[Journeyman]

Plenty of other nations, with significantly fewer cases than us, have used 1.5 or 1m distancing as their guidelines throughout. We're very unusual in having used 2. Therefore, I think it's all a bit academic.

It is, however, blindingly obvious that 2m cannot go on forever.

 

[bramling]

I heard Boris Johnson announce, with lots of trumpeting, the change of social distance from two metres to "one metre plus" from 4th July. But that isn't what the government guidelines say, if I am reading them right. I am responsible for doing the risk assessment for the reopening of our local community hall, so I am looking at them rather carefully. Of course the guidelines for community buildings haven't been issued yet (silly of me to look for them really) so I have looked at the ones for pubs and restaurants instead. What they say is " 2m, or 1m with risk mitigation where 2m is not viable, is acceptable - you should consider and set out the mitigations you will introduce in your risk assessments". So it's 2m, unless you can show that 1m is not viable for your business or organisation in which case you have to mitigate the risk of the closer distance.

And of course, encouraged by the media, people are already interpreting that as one metre plus or minus a bit.

If I am right in my reading of the guidelines, isn't this the most dangerous Johnson fudge yet? It would appear to have been done so that he can make a big announcement which sounds good whilst keeping the scientific advisors onside by writing guidelines which convey a different message if you read them carefully.

At my work the idea of 1 metre plus was comprehensively mocked and derided.

Ultimately the notion of “2 metres where you can but 1 metre will suffice where you can’t” would probably work fine.

Unfortunately we’re really at the stage where Johnson just can’t get anything right now. Essentially he needs to go as he has become a total liability.

I bet Whitty privately knows that he will be the fall guy for all of this, especially once the inevitable inquiry happens.

 

[Journeyman]

At my work the idea of 1 metre plus was comprehensively mocked and derided.

Ultimately the notion of “2 metres where you can but 1 metre will suffice where you can’t” would probably work fine.

Unfortunately we’re really at the stage where Johnson just can’t get anything right now. Essentially he needs to go as he has become a total liability. It’s completely understandable that errors will have been made due to the unprecedented nature of this, however Johnson has a terrible tendency to compound his errors rather than correct them.

I think it's blindingly obvious that the lockdown was rushed into with no planning on how to end it at all, and everything is descending into chaos. I'm in Scotland where the 2m rule still applies, but it's getting increasingly ignored. Not that I'm particularly worried about that, but a lot of people are.

 

[bramling]

I think it's blindingly obvious that the lockdown was rushed into with no planning on how to end it at all, and everything is descending into chaos. I'm in Scotland where the 2m rule still applies, but it's getting increasingly ignored. Not that I'm particularly worried about that, but a lot of people are.

Yes it has descended into chaos now. The mix of boredom, spare time, anger, BLM, Cummings, hot weather, long evenings and alcohol is a potentially troublesome mix.

The atmosphere in London earlier this evening was starting to resemble New Year’s Eve, and there’s increasing issues in my normally docile town with anti-social behaviour, which has kicked off some vigilantism with people infuriated that their sleep is being disturbed when they have to be up for work the next morning.

Johnson needs to cut the fudging pronto, as this is only going to get worse, especially when the pubs re-open. We really don’t want people using the streets as the replacement for being inside a pub.

In that sense 2 metres is the least of our issues at this moment.

 

[Journeyman]

Yes it has descended into chaos now. The mix of boredom, spare time, anger, BLM, Cummings, hot weather, long evenings and alcohol is a potentially troublesome mix.

The atmosphere in London earlier this evening was starting to resemble New Year’s Eve, and there’s increasing issues in my normally docile town with anti-social behaviour, which has kicked off some vigilantism with people infuriated that their sleep is being disturbed when they have to be up for work the next morning.

Johnson needs to cut the fudging pronto, as this is only going to get worse, especially when the pubs re-open. We really don’t want people using the streets as the replacement for being inside a pub.

In that sense 2 metres is the least of our issues at this moment.

Yeah, I really get the feeling that really serious trouble is brewing, and several violent incidents recently seem to be linked to people getting bored, frustrated, angry and stressed. I know I've been all of those over the last three months, especially because I haven't been able to work, and have had a lot of time to stew in my own juices.

This is going off topic, so I'll leave it there - perhaps it deserves its own thread.

 

[BJames]

I heard Boris Johnson announce, with lots of trumpeting, the change of social distance from two metres to "one metre plus" from 4th July. But that isn't what the government guidelines say, if I am reading them right. I am responsible for doing the risk assessment for the reopening of our local community hall, so I am looking at them rather carefully. Of course the guidelines for community buildings haven't been issued yet (silly of me to look for them really) so I have looked at the ones for pubs and restaurants instead. What they say is " 2m, or 1m with risk mitigation where 2m is not viable, is acceptable - you should consider and set out the mitigations you will introduce in your risk assessments". So it's 2m, unless you can show that 1m is not viable for your business or organisation in which case you have to mitigate the risk of the closer distance.

And of course, encouraged by the media, people are already interpreting that as one metre plus or minus a bit.

If I am right in my reading of the guidelines, isn't this the most dangerous Johnson fudge yet? It would appear to have been done so that he can make a big announcement which sounds good whilst keeping the scientific advisors onside by writing guidelines which convey a different message if you read them carefully.

Leaving aside my personal opinions on 1 m vs. 2m, you're right in saying that the official government guidelines and their official position is that it's 1 metre where you can take other precautions (or basically where 2 metres is not possible).

I haven't read the checklists and things that you need to reopen something like a hall and make it "covid-secure", but whatever decision you make you can't please everybody. You'll have some people saying that they want to come back but even 2 metres is not enough and everyone needs to wear masks and sanitise every 2 minutes and ridiculous comments like that. Other people won't really stick to distancing at all. If there's flexibility for you to be allowed to open at 1 metre or 2 metres, you need to decide whether opening with increased distancing would work or is actually necessary as it will cause more disruption than at 1 metre. Some people are still terrified of the idea of coming within 1.99 metres of people, although I think this is finally decreasing to a minority from a majority.

 

[bramling]

Leaving aside my personal opinions on 1 m vs. 2m, you're right in saying that the official government guidelines and their official position is that it's 1 metre where you can take other precautions (or basically where 2 metres is not possible).

I haven't read the checklists and things that you need to reopen something like a hall and make it "covid-secure", but whatever decision you make you can't please everybody. You'll have some people saying that they want to come back but even 2 metres is not enough and everyone needs to wear masks and sanitise every 2 minutes and ridiculous comments like that. Other people won't really stick to distancing at all. If there's flexibility for you to be allowed to open at 1 metre or 2 metres, you need to decide whether opening with increased distancing would work or is actually necessary as it will cause more disruption than at 1 metre. Some people are still terrified of the idea of coming within 1.99 metres of people, although I think this is finally decreasing to a minority from a majority.

2 metres isn’t in itself a bad thing (to be honest in my view it’s something people should always have been attempting to respect even before all this). The key is *where possible*.

Some just don’t seem to capable of striking a balance - some don’t respect the space of others at all, whilst we have the new breed who are terrified of going within 1.99 metres of someone else. Both groups are equally as bad as each other.

I don’t think some silly 1 metre plus tag line is going to have much effect on either group TBH.

 

[Bantamzen]

I heard Boris Johnson announce, with lots of trumpeting, the change of social distance from two metres to "one metre plus" from 4th July. But that isn't what the government guidelines say, if I am reading them right. I am responsible for doing the risk assessment for the reopening of our local community hall, so I am looking at them rather carefully. Of course the guidelines for community buildings haven't been issued yet (silly of me to look for them really) so I have looked at the ones for pubs and restaurants instead. What they say is " 2m, or 1m with risk mitigation where 2m is not viable, is acceptable - you should consider and set out the mitigations you will introduce in your risk assessments". So it's 2m, unless you can show that 1m is not viable for your business or organisation in which case you have to mitigate the risk of the closer distance.

And of course, encouraged by the media, people are already interpreting that as one metre plus or minus a bit.

If I am right in my reading of the guidelines, isn't this the most dangerous Johnson fudge yet? It would appear to have been done so that he can make a big announcement which sounds good whilst keeping the scientific advisors onside by writing guidelines which convey a different message if you read them carefully.

It is a fudge. I made a point of reading the guidance for pubs & restaurants and came away thinking that owners are going to be rightly confused by it all. But basically it comes down to this, maintain a 2 metre distance (which by the way was always a guideline, not an instruction) unless it is not viable, in which case the distance can be reduced to 1 so long as you think about the implications, and by doing so you absolve this less-than-useless government of any responsibility.

 

[LAX54]

I heard Boris Johnson announce, with lots of trumpeting, the change of social distance from two metres to "one metre plus" from 4th July. But that isn't what the government guidelines say, if I am reading them right. I am responsible for doing the risk assessment for the reopening of our local community hall, so I am looking at them rather carefully. Of course the guidelines for community buildings haven't been issued yet (silly of me to look for them really) so I have looked at the ones for pubs and restaurants instead. What they say is " 2m, or 1m with risk mitigation where 2m is not viable, is acceptable - you should consider and set out the mitigations you will introduce in your risk assessments". So it's 2m, unless you can show that 1m is not viable for your business or organisation in which case you have to mitigate the risk of the closer distance.

And of course, encouraged by the media, people are already interpreting that as one metre plus or minus a bit.

If I am right in my reading of the guidelines, isn't this the most dangerous Johnson fudge yet? It would appear to have been done so that he can make a big announcement which sounds good whilst keeping the scientific advisors onside by writing guidelines which convey a different message if you read them carefully.

UK was one of only 3 Countries in the World that used 2M, they said only reason 2 was chosen is that many would not be able to estimate 1M, so make it 2, and you are covered, looking at the beaches, I am not sure any of those could work out what 2m is either !

 

[yorksrob]

Is reduction to 1m a fudge ?

No, just falling into line with what many other countries are doing.

 

[Skymonster]

Setting the distance at 2m was the [totally unnecessary] fudge

 

[Huntergreed]

As far as I could tell. The guidance hasn’t changed, and the recommended distance remains at 2m.

Only in places where 2m is not possible, it’s been permitted to move to 1m but where this is done it must be mitigated.

Many other countries seem to have coped fine adopting 1m without mitigation, goodness knows why this is necessary over here, we must have a different type of virus to everyone else!!

 

[Senex]

At my work the idea of 1 metre plus was comprehensively mocked and derided.

Ultimately the notion of “2 metres where you can but 1 metre will suffice where you can’t” would probably work fine.

Unfortunately we’re really at the stage where Johnson just can’t get anything right now. Essentially he needs to go as he has become a total liability.

I bet Whitty privately knows that he will be the fall guy for all of this, especially once the inevitable inquiry happens.

Is that why at long last he [Whitty] has been so much clearer in public about what he really thinks?

As for Johnson going, that can't happen until all those hordes of Tory Brexiteer backwoodsmen decide their seats are in danger if he stays—but even then he and his gang have shews their contempt for the niceties of politics and will hang on till the bitter end. The biggest problem of all is that the British "constitution" offers no real protection against an over-mighty government. James II shewed us that an over-mighty king can be removed, but no-one ever seems to have envisaged that the problems could come from the House of Commons, especially when there is such a weak Speaker as the present occupant seems to be.

 

[DerekC]

UK was one of only 3 Countries in the World that used 2M, they said only reason 2 was chosen is that many would not be able to estimate 1M, so make it 2, and you are covered, looking at the beaches, I am not sure any of those could work out what 2m is either !

Is reduction to 1m a fudge ?

No, just falling into line with what many other countries are doing.

Setting the distance at 2m was the [totally unnecessary] fudge

All very easy to say, but that doesn't help me very much. I have to decide what the maximum capacity of our hall should be. I could simply shrug my shoulders and say that a lot of people have given up worrying about social distancing and whatever the hall does will make very little difference - but I can't do that. A working lifetime spent worrying about safety might have something to do with it!

The BBC lists five countries which are using 1m and eleven which are using various figures over 1m, up to 2m. So what's the evidence? Here is summary of a recent research paper published by the Centre for Evidence Based Medicine:

https://www.cebm.net/covid-19/what-...tancing-rule-to-reduce-covid-19-transmission/

• The 2-metre social distancing rule assumes that the dominant routes of transmission of SARS-CoV-2 are via respiratory large droplets falling on others or surfaces.
• A one-size-fits-all 2-metre social distancing rule is not consistent with the underlying science of exhalations and indoor air. Such rules are based on an over-simplistic picture of viral transfer, which assume a clear dichotomy between large droplets and small airborne droplets emitted in isolation without accounting for the exhaled air. The reality involves a continuum of droplet sizes and an important role of the exhaled air that carries them.
• Smaller airborne droplets laden with SARS-CoV-2 may spread up to 8 metres concentrated in exhaled air from infected individuals, even without background ventilation or airflow. Whilst there is limited direct evidence that live SARS-CoV-2 is significantly spread via this route, there is no direct evidence that it is not spread this way.
• The risk of SARS-CoV-2 transmission falls as physical distance between people increases, so relaxing the distancing rules, particularly for indoor settings, might therefore risk an increase in infection rates. In some settings, even 2 metres may be too close.
• Safe transmission mitigation measures depend on multiple factors related to both the individual and the environment, including viral load, duration of exposure, number of individuals, indoor versus outdoor settings, level of ventilation and whether face coverings are worn.
• Social distancing should be adapted and used alongside other strategies to reduce transmission, such as air hygiene, involving in part maximizing and adapting ventilation to specific indoor spaces, effective hand washing, regular surface cleaning, face coverings where appropriate and prompt isolation of affected individuals.

Which of course everyone will quote selectively to suit their particular perspective.

It's all very well for the academics to say that " one-size-fits-all 2-metre social distancing rule is not consistent with the underlying science of exhalations and indoor air" and large organisations might have the knowhow and money to pursue complex mitigation strategies, but small organisations and real people need fairly simple rules to comply with. My feeling is that for our hall, with real people who probably won't wear masks or sit facing away from each other (they aren't used to having conversations like that!) two metres is the figure to go for. It's a definitely increased separation compared with what people would do naturally and outside touching distance. I can't say that the hall is "not viable" at the capacity that gives us, so we will stick with it. What the new rule will do, I think, is to allow closer than two metres to get in and out of a row of seats, for example.

My real worry is that most people don't read the detailed advice and just look at the headlines. And what makes me angry is that Mr Johnson and his gang know that and don't care, even if it means some people might die as a result.

 

[DelW]

There's no sudden change in risk at 2m, 1m, or any other distance. The risk of infection reduces with increasing distance, indeed I suspect it's an inverse square law, where it reduces proportionally to the square of the distance apart. Conversely risk increases, probably linearly, with time spent at that distance. However an algorithm based on those criteria would be too complicated for most people to assess easily*.

In the early days of restrictions, two scientists that I heard interviewed on the radio accepted that 2m was an arbitrary value, chosen to give effective reduction in risk without making essential shopping trips impossible. So we're moving from one arbitrary distance to a smaller arbitrary distance combined with additional precautions, which seems a sensible compromise.

(* it's probably similar to noise exposure calculations, which I used to carry out in my professional capacity. They were quite time consuming to carry out by hand.)

 

[LAX54]

Setting the distance at 2m was the [totally unnecessary] fudge

Or as some / many have said the distancing of any distance was a fudge !

 

[yorksrob]

All very easy to say, but that doesn't help me very much. I have to decide what the maximum capacity of our hall should be. I could simply shrug my shoulders and say that a lot of people have given up worrying about social distancing and whatever the hall does will make very little difference - but I can't do that. A working lifetime spent worrying about safety might have something to do with it!

The BBC lists five countries which are using 1m and eleven which are using various figures over 1m, up to 2m. So what's the evidence? Here is summary of a recent research paper published by the Centre for Evidence Based Medicine:

https://www.cebm.net/covid-19/what-...tancing-rule-to-reduce-covid-19-transmission/




Which of course everyone will quote selectively to suit their particular perspective.

It's all very well for the academics to say that " one-size-fits-all 2-metre social distancing rule is not consistent with the underlying science of exhalations and indoor air" and large organisations might have the knowhow and money to pursue complex mitigation strategies, but small organisations and real people need fairly simple rules to comply with. My feeling is that for our hall, with real people who probably won't wear masks or sit facing away from each other (they aren't used to having conversations like that!) two metres is the figure to go for. It's a definitely increased separation compared with what people would do naturally and outside touching distance. I can't say that the hall is "not viable" at the capacity that gives us, so we will stick with it. What the new rule will do, I think, is to allow closer than two metres to get in and out of a row of seats, for example.

My real worry is that most people don't read the detailed advice and just look at the headlines. And what makes me angry is that Mr Johnson and his gang know that and don't care, even if it means some people might die as a result.

That's fine. If your hall can function at 2m, it's probably as well to go for it. However, as you've alluded to, there's no hard and fast point at which it goes from risk to no risk.

As I've said on previous occasions, we need to concentrate on measures that have the most impact on transmission with the least detrimental impact on the economy. Unfortunately I suspect that the second meter is one of those measures with the least impact on transmission and the most detrimental impact on the economy.

 

[Bletchleyite]

As for Johnson going, that can't happen until all those hordes of Tory Brexiteer backwoodsmen decide their seats are in danger if he stays—but even then he and his gang have shews their contempt for the niceties of politics and will hang on till the bitter end. The biggest problem of all is that the British "constitution" offers no real protection against an over-mighty government. James II shewed us that an over-mighty king can be removed, but no-one ever seems to have envisaged that the problems could come from the House of Commons, especially when there is such a weak Speaker as the present occupant seems to be.

The country we all know to have a seemingly powerful constitution (the US) doesn't seem to be doing too well either, to be fair.

 

[Enthusiast]

goodness knows why this is necessary over here, we must have a different type of virus to everyone else!!

No, we have a different type of government, civil service and local authority psyche. In particular the last (who will be outfits who will take it upon themselves to police the "guidance") will absolutely revel in their new tasks to supervise the establishments under their control. I imagine, even as we speak, staff are participating in "Covid restriction compliance" courses up and down the land, pawing over the 43 pages of guidance provided for pubs and devising ways of enforcing that guidance with the threat of licence suspension in the event of failure to comply. That is what will stifle any recovery these outlets hope to make and if we're not careful it will do as much damage as remaining closed because once open they have the full range of expenses to manage.

The reduction from 2m to 1m should have been a simple reduction. No caveats, no "plusses". But the guidance now - at least for businesses who can be browbeaten into compliance - is not really "1m if you can't manage 2m". It will be "2m unless you can show the clipboard wallah from the Town Hall conclusively that you can't manage 1m." The PM's announcement was not so much a fudge. It was a vat of blackstrap molasses into which, if it doesn't go unchecked, large numbers of businesses will simply sink without trace.

 

[DerekC]

No, we have a different type of government, civil service and local authority psyche. In particular the last (who will be outfits who will take it upon themselves to police the "guidance") will absolutely revel in their new tasks to supervise the establishments under their control. I imagine, even as we speak, staff are participating in "Covid restriction compliance" courses up and down the land, pawing over the 43 pages of guidance provided for pubs and devising ways of enforcing that guidance with the threat of licence suspension in the event of failure to comply. That is what will stifle any recovery these outlets hope to make and if we're not careful it will do as much damage as remaining closed because once open they have the full range of expenses to manage.

The reduction from 2m to 1m should have been a simple reduction. No caveats, no "plusses". But the guidance now - at least for businesses who can be browbeaten into compliance - is not really "1m if you can't manage 2m". It will be "2m unless you can show the clipboard wallah from the Town Hall conclusively that you can't manage 1m." The PM's announcement was not so much a fudge. It was a vat of blackstrap molasses into which, if it doesn't go unchecked, large numbers of businesses will simply sink without trace.

Clearly you don't have any idea what goes on in a local authority. i have dealt with them quite a lot. In general they are conscientious people trying to do a good job on a limited budget. The law says that they have responsibility for something (in this case public health) and they do their best to discharge it. I know for a fact that the local authority here have been really helpful for schools in translating the umpteen pages of guff from central government into something that teachers can work with to apply sensible risk mitigation for their individual schools. One of the big problems with government in this country is over-centralisation and the stripping of power from local authorities who do actually know their areas.

 

[Enthusiast]

Clearly you don't have any idea what goes on in a local authority. i have dealt with them quite a lot.

So have I. I worked for one (as a contractor) for a couple of years and have two close relatives who have spent all their working lives working for them That's why I made my remarks. Rather like the manner that central government deals with EU Directives, they have a habit of "gold plating" many of the regulations or guidance that they are called on to implement and oversee. The narrowing of pavements (to accommodate 2m distancing) is typical of this. The guidance says 2m "where possible". Many have chosen to make it possible by reducing road widths and that is impractical. It's not individuals behaving unreasonably - they do as they are told. It is an institutional attitude which cannot be broken and quite honestly they are the very worst institutions to manage anything like "guidance" to enable the safe (but practical) re-opening of businesses. The manifestation of that will be evident when Marstons' pubs are visited by LA compliance teams. As I mentioned on the "has the world gone mad?" thread, that chain has stated that it will not rigidly impose the government's "guidelines." We shall see how they get on when their interpretation of the PM's ridiculous "1m plus" scheme comes face to face with the Local Authority's.

 

[Glenn1969]

Three countries doing badly. All run by populist idiots. USA, UK, Brazil.

Of course it was a fudge

 

[najaB]

Three countries doing badly. All run by populist idiots. USA, UK, Brazil.

The USA and Brazil are, however, in a completely different category of bad than we are. The rate of new infections in the USA is trending upwards again (Thursday was the highest number of positive cases yet*) and Brazil is nowhere near flattening their curve. We started extremely badly but managed to avoid the worst of what it could have been - had they persisted with the herd immunity strategy for another couple of weeks we likely would have been looking at >60,000 dead at this point with a total closer to 100,000 by the end of the first wave. I am worried now though that the fiasco with the track and trace app is going to undo the hard work and sacrifice to date.

To the OP's question - 1m was always the WHO's recommended minimum social distancing so it's not really a fudge, per se.

*Edit: Just looked and Friday's total was even higher!

 

[Bletchleyite]

I am worried now though that the fiasco with the track and trace app is going to undo the hard work and sacrifice to date.

If we can get manual track and trace working properly (i.e. not just a "phone a friend" service, but an investigative service) then the app might not be needed. It does have some flaws, e.g. that the signal, while weak, can go through some types of wall, so you could end up being told to self isolate because your neighbour had it.

I do see (and to some extent share) your concern though.

 

[Nicholas43]

To the OP's question: Yes. "At least 2 metres physical [which inanely and confusingly we call 'social'] distancing, or at least 1 metre together with other measures such as masks or screens" would have been justifiable, and is similar to the clear and coherent guidance issued, for example, by the Swiss railways. "2 metres or 1 plus" is another Great English Muddle which lands people managing any shared space with an impossible task.

 

[Bletchleyite]

To the OP's question: Yes. "At least 2 metres physical [which inanely and confusingly we call 'social'] distancing, or at least 1 metre together with other measures such as masks or screens" would have been justifiable, and is similar to the clear and coherent guidance issued, for example, by the Swiss railways. "2 metres or 1 plus" is another Great English Muddle which lands people managing any shared space with an impossible task.

Erm, both are the same thing, aren't they? Just the wording is different.

 

[Harpers Tate]

I think the thing that is missed by many commentators and critics of any policy on the matter is the level at which these things have to be considered. Quite properly, nobody in the government is directly concerned about (say) the activities in some village hall in Northern England; and whilst it may express concern about half a million people on the beach at Bournemouth, even that isn't in itself a direct issue.

They are most interested (quite rightly) in the collective activities of the entire population and its effect on the Health Service and the Economy.

Put it this way (and I wholly invent these numbers just for illustration):
- if the uncontrolled (so, pre-"lockdown") transmission rate of the disease is {whatever it is}
- if they put measures in place that in theory reduce that by three quarters, to a quarter of its uncontrolled level
- if in fact, nationally, people on average practice those measures half of the time (which may mean some people doing it 100%, some doing it not at all, and some doing it partially)
then you halve the national average transmission rate.

It's only at this kind of level that the government must judge the situation, alongside other matters such as psychological and economic effects.

It only has any degree of control over the measures themselves; not the extent to which people on average practice them; nor on the virus itself. So it is only by adjusting measures that they can (re)act.

If behaviour deteriorates (average, nationally) such that it materially affects the rate; and/or if the measures (which are and can only be estimated in their effect) do not have enough of a reducing effect on the rate; and/or if the virus itself mutates to become more serious; or vice-versa on any or all of these, then the rate will change. If the net effect of changes to these three sees the rate climb again to a point where the Health Service is expected to fail, we may expect a re-tightening of measures. And vice versa.

 

[DB]

It only has any degree of control over the measures themselves; not the extent to which people on average practice them; nor on the virus itself. So it is only by adjusting measures that they can (re)act.

True, and because of that it's important that the measures they advise are clear, specific and backed up with clearly-communicated and evidenced justifications. We aren't seeing that at the moment - measures such as wearing masks because it makes people feel safer (even though the evidence for any benefit is very weak), and vagueness such as 1m plus, really don't help and just look like tokenism.

 

[najaB]

...measures such as wearing masks because it makes people feel safer (even though the evidence for any benefit is very weak)...

Actually, the benefit of wearing masks has been quite strongly proven in situations where adequate social distances cannot be maintained and is recommended by the WHO. It doesn't do much to stop you from getting infected, but wearing a mask significantly reduces the risk of you spreading the infection to anyone else. Countries with a high percentage of mask wearing have some of the lowest infection rates.