Covid-19: Early signs of lockdown restrictions working

The UK's epidemic is still officially estimated to be growing, according to the latest R number, but data suggests new cases are beginning to fall.

The R number - which takes into account cases, hospitalisations and deaths - is estimated to be between 1.2 and 1.3, compared with 1 and 1.4 last week.

This suggests the total number of people with the virus is still rising across the UK.

But in London, where tight restrictions came in earlier, the R number is lower.

In the capital, the estimate - based on data up until 11 January - is between 0.9 and 1.2, compared with 1.1 and 1.4 the previous week.

It comes as a further 1,280 people with coronavirus have died in the UK within 28 days of a positive test, taking the total to 87,291.

The latest government figures on Friday also showed another 55,761 new cases had been reported.

Meanwhile, more than three million people in the UK have now received the first dose of a vaccine - latest figures show the number at 3,234,946.

Although the number of people sick with coronavirus is growing in the UK, data from various sources suggests new infections are declining.

This provides early signs that lockdown restrictions may be taking effect.

The government's scientific advisory group Sage, which calculates the R number, said areas that have been under tougher restrictions for a longer period of time - including east of England, London, and the south east - are showing "a slight decline in the number of people infected".

However, they warned that regions such as north-west and south-west England continue to see infections rise, where the spread of the new UK variant may be playing a role.

The R number is a way of rating coronavirus or any disease's ability to spread. In theory, it describes the number of people that one infected person will pass the virus onto, on average.

In reality, though, the government's estimate of R gives a wider view of the epidemic's general trend since it also looks at what is happening in hospitals.

Cases, hospitalisations and deaths from Covid-19 have been alarmingly high since the beginning of the year and the latest estimate of the R number indicates that the pandemic is continuing to grow.

But because of the way the data to estimate R is collected - it reflects the situation a week ago. More up to date indicators suggest that there's a slight decline in infections in the east of England, London, and the South East.

These areas have had the highest prevalence and therefore the toughest restrictions the longest but infections are continuing to rise in the North West and South West probably because of the spread of the new variant of the virus.

Despite this there's some relief at these figures among the government's scientific advisors. They were not sure whether the current restrictions would be enough to prevent the more contagious variant getting out of control. Now they expect Covid-related deaths to level off in a week or so and then decline as the benefits of the vaccine programme begin to take effect.

Cases should also begin to decrease in the coming weeks. But all this depends on people continuing to observe the government's social distancing guidelines - and come into contact with others only if it is essential.

Prof Sir David Spiegelhalter, a statistician at the University of Cambridge, said coronavirus deaths were likely to peak in the next week to 10 days.

He told BBC Radio 4's The World At One that the lockdown measures were having an impact, with the peak in infections having passed "a good few days ago" which would lead to a reduction in the numbers dying from the disease.

"They are likely to level off in a week - 10 days maybe - at a peak which is probably going to be bigger than the first wave peak of 1,000-a-day, but then should decline due the reductions in cases that we are seeing and, of course, the vaccine programme."

Data from the ZOE Covid Symptom Study app gives its own estimate of 0.9 for the virus's R or reproduction number. This is based on cases alone, rather than a wider number of data sources included in the official estimate.

While this leaves out the fact that hospitals are still filling up, looking at cases on their own allows assessment of whether lockdown restrictions are working.

But the large number of infections recorded at the end of December and the beginning of January means, despite receding cases, hospitalisations and deaths will inevitably continue to rise for some time.

Meanwhile, a ban on travellers from South America, Portugal and Cape Verde entering the UK came into force on Friday as a result of a new, potentially more infectious strain linked to Brazil.

Prof Wendy Barclay, a scientist at Imperial College London advising the government, said this "variant of concern" had not been detected in the UK but another variant from Brazil was already in circulation.

It is not clear whether this second strain is more contagious or not.