There have been reports that the UK government plans to by COVID-19 antibody tests from the pharmaceutical company Roche.
Dr Simon Clarke, Associate Professor in Cellular Microbiology, University of Reading, said:
“The announcement that NHS and care workers are to be offered antibody tests will allow health authorities to determine how many people working in those environments were asymptotically infected during the recent peak. A number of NHS trusts have been screening staff for antibodies routinely, over the last few weeks. It’s not yet clear who else is thought to “need” the test and why. We currently know very little about post-infection immunity to Covid-19, so it could be very dangerous to make casual assumptions about the safety of any staff who have antibodies; we don’t know for sure that this will provide effective immunity or how long it would last for.”
Prof Richard Tedder, Visiting Professor in Medical Virology, Imperial College London, said:
“The Roche assay is designed to detect the presence of antibody to the nuclear protein antigen. I think there is some looseness of thought in the statement from number 10 that this assay provides tests which will be available ‘for people who need them’. Yes, there is value in knowing that somebody has truly been infected but how you use this result and what it means is certainly less clear.
“The inference, and one has to question what data are there to support this, is that the presence of antibody to NP indicates that the person from whom the blood sample was taken has been infected and thus is no longer susceptible to reinfection. Whilst this may in theory be the case until this is proven the presence of anti-NP does not indicate lack of susceptibility to reinfection.
“The presence of neutralising antibody which some tests are able to detect and measure must be used as a confirmatory backup when giving an individual the result of their NP antibody test. At this early stage in the use of serology to inform about the infection status of both healthcare professionals and patients and their families it is essential that an NP result does not modify behaviour since there is no evidence within the NP serological test of the presence or absence of antibody which may neutralise and prevent reinfection. For this reason there are strong recommendations that individuals whose serum contains antibody to NP should also be offered automatically a confirmatory test which is able to detect the presence of virus neutralising antibody.”
Note: NP stands for nucleoprotein and is the internal components of the virus which wraps around the nucleic acid.
Prof Lawrence Young, Professor of Molecular Oncology, Warwick Medical School, University of Warwick, said:
“This is great news which means we can now get a real understanding of the level of past infection in the community.
“Antibody tests will, for the first time, allow us to have a more detailed appreciation of the level of previous SARS-CoV-2 infections in the population. While we don’t know for sure whether the presence of these antibodies means that you are protected from re-infection, increasing evidence suggests that antibodies against the virus will offer some degree of protection. The antibody test will help us to better understand the immune response to the virus and whether it does provide protection. The sensitivity and specificity of the Roche test are very good which means that it is a very accurate test.
“As far as I understand it, the tests on sale from Superdrug and Babylon are very similar. Superdrug is using the Abbott test which has also been evaluated by Public Health England.
“We won’t know about the level of protective immunity indicated by the presence of antibodies until we have more information. All current indications are that these antibodies will provide some protection and could be used in the future for ‘immunity passports’ but only when we know more.
“The availability of ‘over the counter’ tests is a worry if people use these to provide reassurance.”
All our previous output on this subject can be seen at this weblink: www.sciencemediacentre.org/tag/covid-19