While the number of cases transferred to contact tracing fell by 12% to 10,793, the number of close contacts identified rose by 2% to 49,151.
For the first time since the start of August, avg contacts per case was >5.
And of those contacts, the percentage reached has dropped wk on wk for the past 5 weeks, from 90% to 84%.
BUT - this is almost all explained by change in the proportion of close contacts that are from the same household. Which has been plummeting.
There's no change in % of HH and non-HH contacts reached, consistently around 96% and 75% respectively in each setting.
More contacts overall and a greater proportion from a different HH reflects greater social mixing.
And the consequences are also seen in some of the timeliness data.
Percentage of contacts reached within 24 hrs has fallen a touch from 98.2% to 96.% in recent weeks.
But the percent contacts reached from the time the case is transferred to T&T has really deteriorated. Falling from 70% to 46% reached within 24hrs over the last 5 weeks.
The same is also seen in the end-to-end time.
Most recent data show 61% of contacts reached within 3 days of case taking a test, compared with >80% at the end of March.
Finally on this, test turnaround time is relatively stable.
Given
- only small fall in % of contacts reached within 24hrs of being identified
- stable test turnaround times
- but significantly worsening end to end times
it follows that problems lie mainly with time to reach cases rather than contacts.
The report explains that longer time is partially due to international arrivals.
This may make sense if it takes time to identify/log all passengers on a flight.
But once known, contacting should be straightforward as details should be collected following int'l travel
Which in turn, should mean that if international arrivals are partially driving increased end to end time and increasing proportion of non-household contacts seen in the data,
then given contact details of travellers are made available for follow up...
the percentage of non-HH contacts reached should be increasing. Which it isn't.
Unless it's offset by difficulties in reaching non-household contacts of non-travel related cases
Either way, it's not straightforward to unpick and is still unlikely to explain all the changes seen
I'm sure I've missed some explainers/detail here. But bottom line is that while much is still going fairly well, it's all taking a bit longer.
And this all has implications for containing viral spread, particularly around imported cases and potential variants of concern. /end
This week's PHE surveillance report, 26th April - 2nd May
- despite easing of social restrictions & schools returning after Easter hols, case numbers still going down among all ages.
- still regional/local variation
- and ++concerns around variants.🧵 gov.uk/government/sta…
Still some big differences by region - particularly looking at younger adults in Yorkshire and Humber.
Case rates in Y&H are 42/100,000, more than 3 times the rates in the SW at just 12/100,000.
This is even more apparent when looking at data by local authority.
Key points
- lots of changes to LFD use, with differences across the country
- despite falling cases, end-to-end journey time from symptoms to reaching contacts increasing
Case rates & positivity continue to fall across the age groups with no clear sign of pre-Easter rise in school-age cases leading to more infection in older ages.
Highest in 10-19y/o (42 per 100,000) and lowest among 70-79y/o at just 7.2/100,000.
A pattern matched by ONS survey
Case rates also falling across all the regions, with slightly higher rates in Yorkshire and Humber (45 cases per 100,000 compared with just 14/100,000 in the SW).
Again not dissimilar to ONS and good to see case rates come down (next ONS update due tomorrow)
Further drop in cases in the most recent week following a bit of a flattening off in previous weeks - with some of this due to school holidays and fewer LFD tests.
Worth noting that for March, both REACT and ONS surveys suggest that case rates are generally static.
Big drop in LFD use, which is mainly due to a drop in test use by secondary schools (see T&T data).
The drop off has accelerated with the school holidays, but the move from testing in school to at home may have contributed over the past few weeks.