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The Medicines and Healthcare products Regulatory Agency (MHRA) has announced that they are asking providers of COVID-19 antibody tests using fingertip capillary blood samples to temporarily suspend this service whilst this sample type is validated for use with laboratory tests.
Dr Alexander Edwards, Associate Professor in Biomedical Technology, Reading School of Pharmacy, University of Reading, said:
“Whilst there are many benefits of taking samples at home – rather than having to visit a clinic to have a blood sample taken by a healthcare professional – it is vital to ensure that it is as simple as possible to follow instructions correctly, that the process is safe, and that the result obtained is accurate.
“There are several elements that have to be correct. Firstly, home fingerstick blood may not have been checked with the laboratory antibody testing equipment. For example, if the Roche and Abbott antibody tests specify use of blood from the vein collected in a particular tube, switching sample type to a fingertip “capillary blood” may invalidate the test result. Secondly, the effect of time from sample collection to lab testing must be checked. The antibody is likely to be stable, but this needs checking. Finally, if the home user doesn’t find it easy to get enough blood into the collection tube or card, it may not be possible to process the sample- for example if only a small amount of blood is recovered after using the lancet (i.e. the finger-prick device). Everyone is different and although it appears simple, it can take practice to take blood samples correctly.
“It’s important to realise there are two different approaches to home blood tests: a portable disposable test can be used at home (like a pregnancy tester) or alternatively, a blood sample can be taken at home and posted to a laboratory for analysis on a more complex instrument. Both can work very effectively and have advantages and disadvantages. I believe the MHRA has just taken action with “home sampling” services- but it has been very clear from government advice that “home tests” should not be sold until one of these has been approved. The idea of home sampling is that a highly accurate laboratory test can be used but the person doesn’t have to visit a hospital/clinic to have the blood sample taken.
“At home blood testing is used often by certain people, for example many diabetics are very happy to test their own blood glucose levels. Home blood sampling has also been very successfully used by the NHS for specific healthcare services, for example for some infections (e.g. hepatitits and HIV). We should expect to see more and more diagnostic testing outside labs as more portable technology becomes available.
“But because it is not yet clear what the COVID-19 antibody test result means for the health of the individual (e.g. for immunity), this represents a new type of home testing for the UK, and it’s vital this is run carefully and correctly.”
All our previous output on this subject can be seen at this weblink:
www.sciencemediacentre.org/tag/covid-19
Declared interests
Dr Alexander Edwards: Dr Al Edwards is working on research to validate tests at the moment.