Scientists urge caution over availability of antibody tests

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Scientists have warned of the risks associated with the widespread use of antibody tests by employees and the wider public, as the government prepares to announce plans for all NHS and social care staff to be tested.

Dr Claudia Paoloni, president of the Hospital Consultants and Specialists Association, told the Guardian: “The ability to assess who has and has not already had this virus is a major milestone, but there are still a number of unknown factors. The new test’s arrival should not simply be seen as a green light to reduce PPE and other protections for NHS staff who test positive.”

Professor Gino Martini, chief scientific officer at the Royal Pharmaceutical Society, said: “Any antibody test at present can only provide a partial picture. The real issue is that no-one knows the level of immunity that is conferred by having antibodies to coronavirus, how long it might last, and if you can become re-infected.”

Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading, said the tests were “good for satisfying people’s curiosity, but no more”.

He told the Guardian: “Having these antibodies is a reliable way of confirming that someone has been infected previously. Their presence does not indicate that someone is immune, and it should be remembered that any post-infection immunity may dwindle rapidly… We just don’t know enough about what it takes to make someone immune to Covid-19 to accurately test people,” he said.

The government’s move to provide healthcare staff with tests is aimed at allaying fears in the workplace will provided figures on the numbers of people who have had Covid-19. The blood tests, that will be undertaken by hundreds of thousands of workers have to be processed in laboratories. It has not yet been proven that antibodies reduce or remove the risk of reinfection. The length of any immunity gained is also unknown.

Public Health England (PHE) validated three laboratory-based antibody tests, calling them “game-changing”: one from Swiss-based Roche; one from US-based Abbott; and another from the Welsh firm Ortho Clinical Diagnostics. The Abbott tests are sold online by Babylon and Superdrug – among others – from £69, although Abbott itself this week insisted that its tests were not intended to be used by people taking their own blood samples.

NHS medical director Professor Stephen Powis said that people ought to hold off purchasing the tests until government scientists found out more about their accuracy. A further complicating factor was that people with Covid-19 who don’t become very ill may not make high levels of antibody. Will Irving, a professor of virology at University of Nottingham, said: “The sensitivity data will be dependent on what kind of serum samples have been tested. If these are mostly – or all – from hospitalised patients, then the figure may be an overestimate.”

Ortho Clinical Diagnostics managing director Paul Hackworth, said: “The sense we get is that initially it will be used in returning staff and to serve the needs of the vaccine. It will be important to find out how quickly antibody levels that are raised after vaccination wane over time.”

The developments will be keenly observed by companies looking to test employees as they return to the workplace.

In April, Alex Templeton, CEO of test supplier to businesses, Qured, told Personnel Today: “We offer tests in which the samples are collected by the patients themselves at home or at the workplace, and are couriered to our lab partner for rapid analysis. It is a combination of both of these tests which will give UK businesses all the information they need to manage their whole employee population, to ensure that they do not put their colleagues or others at risk while the virus is circulating. With this information, businesses will be able to start planning for bringing their employees back to work safely, in a post-lockdown world.”