The UK government is increasingly alarmed over rising numbers of coronavirus cases, with Matt Hancock, the health secretary, telling MPs on Tuesday that “the virus is still very much with us”.
A range of measures have moved in the wrong direction over recent weeks and show that the jump in cases cannot be explained by increased numbers of tests discovering more people carrying the disease.
The latest test data reported nearly 3,000 coronavirus cases on both Sunday and Monday, and 2,420 on Tuesday. But a more worrying trend is that many of these tests were carried out last week, meaning the rise in positive tests came earlier.
Figures for the whole of the UK show that, for days where enough testing data is now available, there have been more than 2,000 cases every day since September 1.
With an average incubation period of roughly five days, this implies that the rise in caseload coincided with the last week in August, including the bank holiday weekend and the height of popularity of UK chancellor Rishi Sunak’s “eat out to help out” scheme, which encouraged people to dine in restaurants.
Most worrying for the overall numbers is that the rise in positive case numbers is not the result of more testing; rather it has coincided with an increase in the proportion of positive test results.
The positive test rate fell rapidly in the UK during the spring and hit a trough of roughly one confirmed case in 200 tests in mid-July. Since then the rate has started to creep up, and it rose rapidly at the end of August, hitting a rate of one positive result in 100 tests on September 2, the latest date for which full data is available.
This underestimates the true positive case rate because many people take more than one test. In England, the rate of confirmed cases among people who had a coronavirus test has risen to one in 70. Equivalent data is not available for the whole of the UK.
The regional picture shows that there is a wide variation in the risk of catching coronavirus across the nations of the UK and the regions of England. In the most recent weekly period for which data is available, the total number of positive cases per 100,000 of population has been highest in the north-west of England, where infection rates of 38 per 100,000 are on a par with the Czech Republic. The total is lowest in the south-west of England with 8.3 per 100,000 — below that of Germany.
In five areas — the North West, Yorkshire and Humberside, Northern Ireland, North East and the West Midlands — the risk of catching Covid-19 has risen, with infection rates above 20 per 100,000 in the most recent week. This is the threshold the UK’s governments have used to judge whether returning travellers from foreign countries must endure a 14-day quarantine period.
In the northern town of Bolton, where restrictions were reimposed on Tuesday, the rate has jumped to 120 per 100,000.
In all areas of the UK the risk of catching Covid-19 has risen over the past month, and has more than doubled in most nations and regions.
However, the risk of catching coronavirus remains far lower than at its peak in March and April. This can be seen in the age profile of confirmed cases. At its peak, testing was limited to those who were very sick, so was concentrated among older people, who are more vulnerable to the virus.
Now, with testing much more extensive, the incidence of coronavirus is most likely to be recorded for those in their 20s.
Professor James Naismith, director of the Rosalind Franklin Institute, said: “At the moment, most people with the virus are young. The virus has not changed, it is not suddenly targeting young people. Rather, our testing is developed enough to see what we missed at the start of 2020: the virus spreading in younger, more social elements of society.”
The drop in infection rates among the elderly explains the continued low levels of hospital admissions for people with coronavirus symptoms and the lack of any increase in death rates.
This shows the difference with the initial months of February, March and April, when the recorded numbers rose very sharply even though there was an acute shortage of testing capability.
Although the number of positive tests is now creeping up to the levels of late March, a greater proportion of the virus is now diagnosed across the UK than it was then.
And despite the growing number of positive tests, the increase in the rate of infections is now much lower than it was in the spring. Cases were doubling every three days in the first wave but are now rising much more gradually.