A brief thread about why this is a dangerous time to be opening schools in the UK - and why the narratives around this being reasonable just because R is below 1 don't make sense.
As of yesterday, the govt reported 384 deaths from COVID-19. R determines the slope of decline or increase in cases & therefore, deaths from this point. If the R is above 1, we see exponential rises. The level to which R falls below 1 determines the gradient or speed of decline.
While we are seeing daily decline in deaths within the UK, this has been gradual. At this point, the government policy should be to reduce R as far as possible to bring the number of new cases down to very low levels. Why does this matter?
This matters, because opening schools & easing lockdown is likely to be associated with an increase in community transmission. This has been seen to some extent in Denmark and Germany after they started easing lockdown, even though the R remains below 1 in these regions.
But it is very possible that easing lockdown measures, even if it doesn't push R above 1, will at least dampen the decline in R, which means the decline in number of cases and deaths may not be as rapid as it may have been had these measures not been lifted.
The point where we start from in terms of new cases and daily deaths matters here. So for example if we started with say 10 cases/day, even if R remained at 1, we would expect cases to plateau at 10 new cases/day.
But, if we start from a point of 3000 cases/day & ~400 deaths/day, & R remains at 1 or just below 1, we will continue seeing new cases & deaths at the level we're seeing now. This means the cumulative death toll will be much higher as a result of not reducing R rapidly.
Similarly if R does go above 1, exponential rises mean a very different death toll starting from 400/day compared with 10/day. And let's remember that we will not pick up changes in R immediately, as there is a time lag.
So even if we act as soon as we pick this up, there will be a time lag during which exponential growth will continue as it did for weeks following lockdown, making the cumulative death toll much higher starting from the point we're at now, relative to easing at lower case levels
European countries that did open schools did this when their daily case numbers and deaths were far lower than in the UK currently. Germany had deaths below 100/day & ~500 confirmed cases/day when schools started re-opening. Denmark had 170 cases/day and 10 deaths/day.
Opening schools & easing lockdown at this point in our outbreak is negligent, even if it doesn't bring our R above 1. At this point of the outbreak, the aim is to rapidly reduce R to the lowest level possible to reduce the number of daily deaths.
If we continue with an R level just below 1, expect to see the daily deaths to continue at this level. This strategy would have led to far lower preventable deaths had we implemented this when our case numbers were far lower than they are now. This is a very negligent step.
And I'm not even discussing us not having preparations for testing, tracing or isolation in place - which would've been other aspects to consider. Even if we had all that in place, which we don't, the timing of easing measures will lead to many more preventable deaths.
