Coronavirus: Estimated speed of coronavirus infections rises over past week

The official estimate of the pandemic “R” number has risen slightly over the last week, according to a consensus by scientists advising the government.

The Scientific Advisory Group for Emergencies (SAGE) said the UK reproduction number for the coronavirus is now between 0.7 and 1, up from 0.5 to 0.9 last week.

The slight increase, based on calculations done by six research groups, is being attributed to cases in care homes and hospitals accounting for a greater proportion of the overall total.

It is too soon after the easing of the lockdown for increased movement of people to show up in the data.

R is a measure of how fast a virus is spreading. Above 1 an outbreak is growing; the further below 1 the faster it’s shrinking.

It’s estimated using data from hospital admissions, intensive care demand, deaths and the number of social contacts people have.

Health Secretary Matt Hancock said the R number was based on data from around a fortnight ago and he did not believe the figure was above one.

Speaking at the government’s daily news briefing, he said: “We are constantly keeping the R under review. We don’t think that it is above one. So that meets that test.”

He told Sky News: “On the timing, this is based on data from a couple of weeks ago because of the way it is measured but also from the survey data that the ONS (Office for National Statistics) has published.

“And as that survey grows, the measure of R will become more timely but even in countries that have had large-scale survey testing for some time like Germany there is still something of a lag.

“It is an incredibly important figure for policymakers but it is one data point to look at alongside the level of new cases.”

Deputy chief medical officer Dr Jenny Harries explained the reasons for a range in the R number.

She said: “Partly because a number of different models are used to model this data and it’s important that they challenge each other and that we get the consistency of that.

“Partly, the data comes from historic data. Obviously we can’t predict precisely so we’re estimating it on different sources of information so things like hospital admissions that have happened historically.

“And then I think thirdly importantly, we know that we have slightly different R values relating to some areas of risks.

“So obviously in recent weeks, care homes have been heightened interest, hospitals also and we keep an eye on those. So this is very much a national average.”

SAGE is currently trying to calculate regional R numbers to reflect higher transmission in the North East and Scotland and lower rates in London.

A modelling study by Public Health England and the Cambridge MRC Biostatistics Unit has concluded that the R number in London could be as low as 0.4, with an estimate of just 24 new cases a day.

But government scientists are understood to be sceptical that the number of new infections is that low.

The Department of Health confirmed another 384 coronavirus-related deaths were recorded in the UK on Thursday, bringing the total number 33,998.

There were 49 patients admitted to hospitals in London yesterday.

For every admission there are likely to be 20 other cases in the community – bringing the total number of new infections closer to 1,000.

Estimates of the R number are notoriously difficult because of the lag between the point at which people are infected and the time that data is collected.

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For example it takes roughly 10 days for people to become sick enough to need hospital care.

The prime minister has said that easing the lockdown will depend on both the R number and the number of new infections.

The lower the number of daily cases, the easier it will be to trace their contacts and stop flare-ups of the virus.

(c) Sky News 2020: Coronavirus: Estimated speed of coronavirus infections rises over past week