Thread by @deeksj

BBC News - Coronavirus antibodies tests 'put public at risk' bbc.co.uk/news/health-53…

Our review of websales of COVID-19 antibody tests reported after @BBCNewsnight with @deb_cohen @charliehtweets last night. Joint work Uni Birmingham @UoB_IAHR @TERG_UoB and Uni Warwick.

1/11

Full report is available as a pre-print led by @siantphillips2

Information given by websites selling home self-sampling COVID-19 tests: An analysis of accuracy and completeness medrxiv.org/content/10.110…

2/11

A simple search of UK and US websites (end of May) found 27 websites selling 41 tests direct to user home self-sampling and testing for COVID-19. Seems a particular UK problem as 39 tests were for sale in UK and only 2 in US.

3/11

Many websites DID NOT provide

the name or manufacturer of the test (32/41; 78%),
when to use the test (10/41; 24%),
test accuracy (12/41; 29%),
how to interpret results (21/41; 51%).

4/11

Sensitivity and specificity were the most commonly reported test accuracy measures

either were reported for 27/41 (66%) tests;

We tried to link these to evidence - but could only link these figures to manufacturers documents or publications for four (10%) tests.

5/11

Predictive values were not reported but indirectly implied

for 5 tests wesbites said “if it shows a positive result, it can only be for COVID-19” implying PPV=100%

four tests stated that tests sometimes show a negative result even if you are infected implying NPV<100%

6/11

For molecular virus tests,

only 9/23 (39%) websites explained that test positives should self-isolate,

and 8/23 (35%) explained that test negatives may still have the disease.

7/11

For antibody tests,

12/18 (67%) websites explained that testing positive does not necessarily infer immunity from future infection.

8/11

Seven (39%) websites selling antibody tests claimed the test had a CE mark, when they were for a different intended use (venous blood rather than finger-prick samples).

9/11

After MHRA stopped use of finger-prick samples

2 websites still selling
4 providing venous blood sampling
2 sent kits for purchaser to find own phlebotomist
6 stated out of stock / unavailable,
4 reported MHRA guidance and indicated that they had suspended sales.

10/11

Conclusions:

Web sales of home self-sampling COVID-19 tests

provide incomplete and in some cases misleading information about:

test accuracy,
intended use
and
test interpretation.

We MUST DO BETTER. Can the regulators read our paper and help?
@MHRAgovuk

11/11