The fall in UK Covid-19 cases isn’t due to less testing

The number of Covid-19 cases in England fell by a third in a week, while the number of PCR tests fell by 12 per cent.

An office worker wearing a face mask crosses London Bridge on 19 July 2021. (Photo By TOLGA AKMEN/AFP via Getty Images)

With many surprised by the fall in UK Covid-19 cases over the last week, some have suggested this is due to a reduction in testing, but analysis of daily testing numbers shows this isn’t the case.

Covid-19 cases in England are decreasing faster than testing rates

Covid-19 cases by date reported, and PCR tests by date published in England, percentage change as compared to previous week, seven-day rolling average

On a week-on-week basis, the number of Covid-19 cases in England is falling faster than the number of PCR tests. If the declining case numbers were attributable to a lack of testing, we would expect to see the opposite.

Just over two million PCR test results were published from 21-27 July, which is a 12.4 per cent decline on the previous seven days. But analysis of Covid-19 cases in the same period shows a much larger decline of 32.4 per cent.

Between 1 June and 20 July, the seven-day PCR positivity rate rose from 1 per cent to a peak of 11.8 per cent, but since then has begun to decline.