Adam Kucharski: A country has "transmission budgets" for Covid
https://www.telegraph.co.uk/global-health/science-and-disease/analysis-blm-protests-crowded-beaches-eased-lockdown-have-not/
Dr Kucharski suggests the concept of "transmission budgets",
where the value of R is broken down into its constituent parts,
is a useful one for policymakers looking forward.
"Countries essentially have a 'transmission budget' when it comes to Covid-19," ....
"Global patterns suggest there are only so many things that can go back to normal before flare-ups start happening".
One problem in the UK is that we don't know with any precision how different measures, such as school or office reopenings, contribute to the overall budget.
However, there is some evidence from overseas.
A study conducted in Hong Kong when schools were closed and track and trace was operating was able to isolate and measure the effect of other interventions as they were introduced and then relaxed.
"One of the most consequential physical distancing measures appears to be the work at home policy for civil servants, which was mirrored by many other institutions and private employers", say the authors.
"We estimated that
the effectiveness of implementation of civil servants working from home was 67 per cent
and the effectiveness of implementation of additional physical distancing measures including closure of high-risk places/facilities [such as bars and restaurants] was 58 per cent."
A separate study looked at nine interventions in 41 countries between January and April 2020 and found eight of them to be effective.
Closing schools reduced R by an average of 50 per cent.
Other things that worked included:
closing non-essential businesses (34 per cent);
closing high-risk businesses (26 per cent);
limiting gatherings to 10 people or less (28 per cent);
and issuing stay-at-home orders (14 per cent)
....
"Working out these budgets is incredibly difficult,"
says Prof Hunter, who like many other experts urges caution in the absence of firm evidence.
"We don't know with certainty what the real numbers are for each activity in the UK."