R number for Covid-19 transmission across the UK is falling and may be below 1

The reproduction number, or R value, of coronavirus transmission is falling across the UK and may potentially be below 1, according to scientists.

The Scientific Advisory Group for Emergencies (Sage), which advises the Government, said on Friday the R for the UK as a whole is between 0.9 and 1. Its current prediction represents the situation over the last few weeks.

R represents the average number of people each Covid-19 positive person goes on to infect.

When the figure is above 1, the Covid-19 epidemic will continue to grow but if it is below 1, it shows the outbreak is in retreat.

Last week, the R number was said to be between 1 and 1.1.

Experts believe that the R number is already below 1 in some places, particularly in parts of Yorkshire and potentially parts of the north-east as well as the north-west of England.

Meanwhile in London, the R number is between 1 and 1.1.

According to a Government adviser, the Government’s new Tier 3 and Tier 2 interventions, which are due to come into effect on December 2, should keep the R number below 1 in the run up to Christmas.

But areas in Tier 1 may continue to see a growth in coronavirus infections, they added.

The estimates for R and growth rate are provided by the Scientific Pandemic Influenza Group on Modelling (SPI-M), a subgroup of Sage.

The growth rate for the UK, which estimates how quickly the number of infections is changing day by day, is between minus 2% and zero.

The most likely value is towards the middle of that range, experts advising the Government say.

Sage has also said that a divergence in policies across the four nations that constitute the UK mean “the estimate of R for the entire UK has become less meaningful in recent weeks”.

The experts said the impact of the lockdown measures introduced in England on November 5 are beginning to be observed this week and cannot yet be fully evaluated.

But they estimate that R for England may continue to decline and “may be below 1 for all regions already”.

SPI-M use several different models and data from a variety of sources to estimate R and growth rate.

This includes data such as the number of people testing positive, hospital admissions and deaths.

It comes as new figures from the Office for National Statistics (ONS) on Thursday showed there were an estimated 633,000 people in private households in England with Covid-19 between November 15 and 21 – a slight decrease from 664,700 the week before.

The Covid-19 Infection Survey is based on more than 712,000 tests gathered from households across the UK over the last six weeks, regardless of whether people have symptoms.

The ONS said that “in recent weeks the positivity rate in England has shown signs of levelling” with around one in 85 people infected with coronavirus in the week November 15 to 21.

When it comes to age groups – only secondary school age children are seeing a rise in infection rates, while they have dropped in adults aged 35 and over, according to ONS figures.