20th May 2020

COVID-19 Antibody Test Approved by Public Health England

One thing that will hasten the end of lockdown and a return to normal life is a widely available antibody test for COVID-19. The reason this is so important is that unlike the present swab test for coronavirus which only tells you if you are currently infected, a reliable antibody test can tell you if you’ve already had COVID-19 and recovered, even if you didn’t have any symptoms.

A positive antibody test would mean that those people would be safe to return to the work place, because they would no longer be contagious, and are likely to have some immunity from re-infection, at least for a few months.1,2 This would obviously have huge implications, including a swifter easing of lockdown, and the financial benefits of people returning to work and businesses resuming trading.1

These issues and the current progress towards a widely-available antibody test were the focus of an article in The Telegraph1 on 18 May (see Reference 1 for a link to the article). Here, the article states that Public Health England has approved a COVID-19 antibody test developed by the Swiss pharmaceutical company, Roche. This follows approval by the US and the granting of a CE kite mark by the EU.2 The test, which relies on a blood sample taken by a healthcare professional, uses antigens to detect antibodies to SARS-CoV-2 (the virus responsible for COVID-19). Antibodies are proteins in the immune system which bind to foreign bodies (antigens), such as viruses, and signal immune cells to attack and destroy them. With the antibody test, if the blood sample contains antibodies to COVID-19 from prior exposure, they bind to COVID-19 antigens in the lab-based assay to give a ‘positive’ test result.

How accurate is the Roche antibody test?

According to Susannah Fleming and Carl Heneghan from The Centre for Evidence-Based Medicine2, Roche report the test to have “a specificity greater than 99.8% and a sensitivity of 100%.” These figures sound very impressive, but what do they mean? Sensitivity refers to false negatives, so a sensitivity of 100% means that everybody who has had COVID-19 who takes the test, will get a positive result. Specificity refers to false positives, so a specificity of 99.8% means that among all those who take the test who have never had COVID-19, 0.2% of them will get a positive result, and 99.8% will get a correct negative result.2 The Roche antibody test is clearly extremely accurate and will no doubt be put to good use in the coming weeks and months to help people return to work safely.

Who will the test be available to?

The Roche test will be available mainly to those in the NHS and social care settings initially,2 and not the general public. Geoff Twist, the managing director of Roche Diagnostics UK and Ireland is reported in The Telegraph article as saying that the company is ‘working with the government and the NHS to enable the company's test to be rolled out across the UK as soon as possible’.1 The test will benefit the NHS because it will enable the identification of NHS staff who have contracted COVID-19 and hence recovered, allowing them to return to their vital work on the frontline.1

What about home-testing for the general public?

While the general public can buy home-testing kits online from other countries, no home testing kits have received a CE mark (signifying that they meet the requirements of medical device regulations), so there are currently no testing kits available in the UK for home use.3 However, Government advice is that this may change.3 A home-testing kit would be based on a finger-prick blood sample, and any COVID-19 antibodies would bind to antigens in the test unit and, with the aid of a dye, produce a visible ‘positive’ result which could be read at home.1

Therefore, according to The Telegraph article, it could be several months before an effective COVID-19 home-testing kit becomes available.1 But there is much to be hopeful for. There is a lot of ongoing research into home-testing kits and, in the meantime, lab-based antibody testing will pave the way for the timely return to work of NHS and social care staff, and no doubt other sectors of the workforce in due course. Life may never go back to how it was, but we can all look forward to a gradual easing of lockdown and a return to a new, safe, normal. 

 

References

1. How do coronavirus home antibody tests work, and how do I get one? The Telegraph. 18 May 2020. Available at:   https://www.telegraph.co.uk/news/2020/05/18/antibody-test-coronavirus-uk-covid-19-buy-when/

2. BBC News: Health. Covid antibody test a 'positive development'. 14 May 2020. Available at: https://www.bbc.co.uk/news/health-52656808

3. Fleming S, Heneghan C. COVID-19: Roche Antibody Test – 14th May. The Centre for Evidence-Based Medicine. 14 May 2020. Available at: https://www.cebm.net/covid-19/covid-19-roche-antibody-test-14th-may/

4. MHRA. Guidance for patients, the public and professional users: a guide to COVID-19 tests and testing kits. Published 13 May 2020. Available at: https://www.gov.uk/government/publications/how-tests-and-testing-kits-for-coronavirus-covid-19-work/for-patients-the-public-and-professional-users-a-guide-to-covid-19-tests-and-testing-kits