March 24, 2020

expert comment on the need for accurate tests to detect COVID-19 antibodies

There have been questions from journalists about the need for COVID-19 antibody tests, as well as an announcement by the Health Secretary, Matt Hancock, that the government have purchased 3.5 million antibody tests.

On Matt Hancock’s announcement:

 Prof Paul Hunter, Professor in Medicine, University of East Anglia (UEA) said:

“In today’s briefing Matt Hancock announced that they had bought 3½ million antibody test kits. Such tests will effectively tell you that you have already had the infection and therefore most likely to be immune. This is really good news as such antibody tests will be essential to the management of the epidemic as the epidemic progresses for several reasons.

1. Any essential worker who is antibody positive can go back to work without worrying whether or not they are putting themselves or their families at risk.

2. If the availability of personal protective equipment starts to fail then it may be necessary to use that equipment primarily for people who are still susceptible (antibody negative) – This is not a situation that anybody would want but in dire straits may be forced on us.

3. For people who are particularly vulnerable and taking even greater distancing measures could relax these if they are shown to be immune.

4. When vaccine first becomes available it is likely to be in short supply. Such an antibody test would help make what vaccine is available go further as testing would allow the vaccine be used just for people who are not already immune.

5. One of the big uncertainties around COVID 19 are the number of asymptomatic people in the population. This information is crucial to determining the ultimate trajectory of the epidemic. Estimates vary dramatically of the number of asymptomatic infections with Lourenço and colleagues from Oxford presenting a model that suggests that up to 60% of the population may already be exposed, which would dramatically affect the ultimate number of cases. The reality is that we do not yet have any hard data on this and the antibody test will be essential to try and answer this essential question.”

Dr Alexander Edwards, Associate Professor in Biomedical Technology, University of Reading, said:

 “I’m delighted to see how quickly that these antibody test have been developed, which demonstrates the value of decades of research into antibody based blood testing. We would expect these tests would have been evaluated carefully for accuracy, and once again I urge individuals not to seek to purchase unlicensed tests in case they are unreliable. Bear in mind that antibody tests need to be used carefully to make sure they give useful results, and be patient if you are suffering at home- you will get tested when needed. Even 3.5 million tests could get used up very quickly, let’s help support our front-line NHS staff by making sure these tests are used in the most urgent way, for example to safely allow clinical workers back to patient care without risking passing an infection on.”

On the need for antibody tests:

Prof David Wraith, Professor of Immunology and Director of the Institute of Immunology and Immunotherapy at the University of Birmingham, said:

“As pointed out by Mark Walport, Chief Exec of UKRI, the critical tools that we need to provide long-term control of the coronavirus (COVID19) infection are first an effective vaccine and second, a test to define the immune status of people who have or who may have been infected.

“Various companies have recently reported development of tests for anti-SARS-CoV-2 antibodies, including the finger-prick assay that is to be used in the UK. At present these are not extensively tested but will give a +/- readout of immune status.

“Scientific publications released this week, show that it will be possible to establish a more accurate way to detect anti-SARS-CoV-2 antibodies. This is important because antibody tests will give us a safe way to judge whether or not someone is infected since we now know that antibodies appear shortly after symptoms.

“This will allow us to distinguish those people who have had SARS-CoV-2 versus the many other bugs that are flying around at this time of year and can give similar symptoms. This is a key point: the information provided will tell us who among individuals in our NHS and other essential workforces are immune to the virus and, therefore, safe to return to their vital work.

“For many people, it is difficult to know whether they have had a cold, flu or SARS-CoV-2: if these individuals don’t need to self-isolate for long periods then they can return to the critical workforce confident that they have built up immunity to the infection. However, a more sophisticated test than those currently available is required to assess the type and strength of immunity that correlates with effective and long-term protection.

“Furthermore, when a vaccine for this virus comes along, we must have a validated and quantitative assay for us to test the vaccine. In the meantime, we need a validated test to identify individuals who make strong immune responses who could donate antibodies to those who are severely affected. We could also isolate antibody genes from such strong responders to reproduce their antibodies in the laboratory and use them as drugs for immunotherapy of critically ill patients.

“Much work still needs to be done to optimise the sensitivity, validate the assay and put this onto a platform that can be used readily. This work is critical and urgent and Universities, particularly UK universities, will be key.  We in Birmingham have the expertise required for this and will work with industry to do all that is required to produce an effective test.”

All our previous output on this subject can be seen at this weblink: 

www.sciencemediacentre.org/tag/covid-19/

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