COVID-19: MOBILE TESTING DAY 2

Yesterday I reported on the mobile testing unit set up in a car park behind my local Tesco's in Oxford.  I walked past it again today at lunchtime, and can report:

• There were 4 people being swabbed.  Male and female, younger and older adults, whites and browns.  COVID-19 is indiscriminate.  Out in the open, no privacy, but that's not too much of an issue
• The security guard told me there had already been about a hundred people tested today, and hundreds yesterday.  Difficult to know if that is an exaggeration.

I understand from a reliable source who has tried to book a test that they are only accepting people in two situations:

1. Symptomatic
2. Been contacted by a tracer from NHS Test and Trace who has asked them to get tested

The rules for a negative result include that the person tested should continue to self-isolate unless:

• "everyone you live with who has symptoms tests negative"
• "everyone in your support bubble who has symptoms tests negative"

This means two major problems:

• People who are not yet symptomatic don't get tested, unless specifically requested by NHS Test and Trace.  It is they who are out and about not realising they are infectious
• People returning from abroad don't get tested until become symptomatic.  Depending on the country visited, they are supposed to continue to self-isolate for 14 days regardless.  That is grossly unfair if not carrying COVID-19.

Effectively tests are being rationed, I imagine for three reasons:

• The reagents are in short supply
• There is only so much lab capacity and staffing
• The tests are expensive.  The Financial Times suggests £100 a test using current testing methods, which may only be reagents and swabs.

INFECTION RATES

As at 21 August, Oxford was 17th highest for new infections on the list of English towns, cities and districts.  It has officially been placed on Amber alert.   The data for the last 7 days, as below, suggests 40 new cases in Oxford localities, but rather oddly 1 or 2 cases in each locality are not counted.

So let's say 44 in the last 7 days, or 6.3 per day.  That's 28.9 cases per hundred thousand per week, 4.1 a day.

These daily figures, derived from usual testing arrangements without the mobile units, need to be multiplied by at least 5 to reflect:

• Not all symptomatic people get tested, possibly only 1 in 3
• Swabbing, especially self-swabbing, creates false positives up to 30%
• Asymptomatic people, who can still be infectious, are at least 50%

If we then assume that people are infectious for an average of 5 days before they self-isolate, 6.3 x 5 x 5 is maybe some 160 people infectious out and about in Oxford.  These are not tested and not realising they are infectious.

If hundreds tested at the mobile testing has been the case, even if exaggerated, there may be an even higher level of COVID-19.  It typically takes 5 days to display symptoms, so we know results are about a week behind the true rate.  There could truly be a major COVID-19 problem in Oxford !


ADVANCES IN TESTING

Currently tests are carried out using a complicated technique using RT-PCR technology.

By coincidence it is an Oxford University spinout Oxsed Limited that has developed a test using RT-LAMP technology that can give results in minutes at under £20 per test. Currently being evaluated

Other acedemics and commercial businesses across the world are also trying to improve testing.  The holy grail is to be simple, quick and cheap enough to support mass testing at home of everybody every few days, or even daily.


News from the USA is of "inexpensive paper-based test ...described as being similar to at-home pregnancy tests".  There are at least three such developments.  Watch this space as such tests would be transformational. "As long as those testing positive stay home, a cheap, at-home testing regimen has the potential to provide a kind of artificial herd immunity, interrupting enough transmission nationwide to cause the pandemic to stall."  As effective as vaccines.


IN THE MEANTIME

From a personal perspective, I need to protect myself:

• I have a simple rule not to go inside premises unless essential, such as for food or to buy a drink to then sit out in a pub garden.  Going to be more difficult as summer turns into autumn

• I have bought a small bottle of 60% alcohol sanitiser.  Tesco's provides this to wipe basket and trolley handles at the entrance, but the local Co-op Food doesn't.  Other premises often provide anti-bacterial sanitisers that are ineffective against the virus that causes COVID-19

• As I leave the house I wear a "surgical mask" to the EN14683 standard.  This is primarily for source control, to reduce the chance of someone infectious infecting someone else, but is also regarded as providing a little protection to the wearer.

• In the context of viral transmisison in "aerosols", clouds of microdroplets that can float across rooms, I am also looking to buy a visor to provide myself with some extra protection.  That matches what is now expected of hairdressers, and often seen worn by people serving in restaurants. Not easy to source, but must be available.

IN CONCLUSION

Oxford has a major COVID-19 problem, and is on the verge of a local lockdown.  This is a problem in many towns and cities across the UK.  I'm taking personal precautions.  But unless everyone realises the risks to young and old, and takes COVID-19 seriously and adopts precautionary measures, we won't be able to keep schools open, nor properly re-open the economy.

I've said it before and I'll say it again and again.  We need a #NearZero policy and strategy, similar to but more pragmatic than ZeroCOVID, plus a far better public information campaign.

Here is Day 3, when I got tested.