This week's Test & Trace report shows another big jump in cases, only partly driven by a surge in demand for testing.

Test turnaround times continued to get worse as the system was overstretched, and contact tracing still isn't good enough and shows no real signs of improvement.

With delayed test results now in, last week the number of people testing positive jumped by 52%.

This week it's already up by another 75%, and again there were over 60,000 people still waiting for results from their tests by the end of the week!

So probably over 19,000 cases.

The number of new people tested went up by 27% and the total number of tests by 24%, but this is far less than the jump in new cases.

As a result, the percentage of people testing positive also went up again.

NOTE: figures below are estimated (see end of thread for details).

As demand rises, labs are struggling to keep up, creating a backlog.

In total 66,020 of last week's tests hadn't delivered a result when the report was compiled.

Most of the previous week's backlog was cleared, but 14,316 still haven't given a result and probably never will.

The average time taken to deliver results is also going up across all types of test, with Home test kits and Satellite test centres worst hit.

Satellite testing is mostly the regular testing of care homes, which shows why so many care homes have been complaining about delays.

Regional (drive in) sites only delivered 16% of test results within 24 hours of booking, the worst figure since June.

18% of tests took more than 48 hours to give a result, including 1.3% that are still waiting.

This is actually as good as it gets.

The report now lists Local (walk up) sites that don't usually require a booking as a separate category. But oddly still gives time taken to get a result from when test was booked.

I believe these are generally in hot spots.

Their performance is just as bad as Regional sites.

Interestingly we can now see how testing has shifted from Regional sites across the country to Local walk up sites focused in hot spots.

This explains why it's been so hard to book a test recently in other areas - Regional test availability has gone down while demand has soared.

Mobile test sites are also showing their worst performance since June, with only 16% of tests giving a result within 24 hours of booking and 21% taking more than 48 hours.

As with Regional and Local sites, more than 1% of tests didn't give a result at all by the end of the week.

"Sent out" tests are where it gets really bad though.

Satellite testing (eg care homes) saw most tests still taking over 72 hours to deliver a result and 49,106 tests (14% of the total) hadn't delivered a result by the time the report was compiled!

This is where the backlog is.

Home tests are also suffering, with most still taking more than 72 hours to deliver a result, and 13,446 tests (8% of the total) not delivering a result yet.

All of these incomplete tests will have carried over to this week. Some of them will never be processed.

Meanwhile the national contact tracing system run by Serco and chums is pretty much static, and far below the level required.

First the good news - despite a surge in new cases they still managed to reach 82% of them, and mostly within 24 hours of being referred to the system.

The bad news is they're still only reaching slightly less than 64% of the contacts they're given by those cases.

This is actually the best they've managed so far, but it's still far short of the 80% experts say they need to reach.

Other parts of the UK are managing 90%+.

So overall then cases are surging, the testing system is struggling to keep up, tens of thousands of people are having to wait days for their test results, and the contact tracing system is still far below the level it needs to reach to be effective.

And next week will be worse.

This week's Test & Trace report and accompanying data can be found here - https://www.gov.uk/government/publications/nhs-test-and-trace-england-and-coronavirus-testing-uk-statistics-3-september-to-9-september-2020

My analysis of last week's report is here, for comparison - https://twitter.com/_johnbye/status/1304123162997686272?s=20

And here's an explanation of how I estimated positivity rates, and why I didn't just divide the number of people testing positive by the number of people tested.

TLDR: the number of people tested doesn't include anyone who's ever been tested before! https://twitter.com/_johnbye/status/1304320944983465984?s=20

Also worth noting that as demand is now outstripping capacity for testing, the number of new cases will increasingly be underestimated, and more and more people won't be referred to contact tracers at all because they never got a test.