Coronavirus: Antibody test lacks ‘proper evaluation’

A nurse wearing protective equipment draws blood to detect COVID-19 antibodies at a clinic in MoscowImage copyright
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Antibody tests are carried out in other countries, such as Russia

Experts caution that the Covid-19 antibody tests for the NHS and care staff are being implemented without a “proper evaluation.”

Testing could place an unnecessary burden on the NHS, the 14 senior academics say in a letter to the BMJ:

Last month, the government said it had purchased 10 million antibody tests and asked the NHS trusts and residences to make them available to staff in England.

Authorities say blood tests, to see if anyone has had the virus, will play an “increasingly important role.”

They are also offered some patients and people who have routine blood tests in England.

What are antibody tests?

They usually show whether someone who has not previously felt good about a mistake has developed protection against future attacks of the disease.

But how the immune system reacts to the Covid-19 virus remains uncertain.

With current laboratory tests, says NHS England, a positive result shows that a person has had coronavirus.

But crucially, it does not prove that they have immunity against future attacks or if they could transmit the virus to others.

However, health officials say collecting the results of these tests will help them understand more about the spread of the disease.

What are the concerns?

The group of scientists says that as a positive result they are unable to prove immunity, the tests offer “no benefit” to hospitals and care staff.

The results do not change what personal protective equipment should be worn by staff, for example.

Academics also suggest that there is little data on how well the test works for people at higher risk, including people belonging to some ethnic minorities and older patients.

Instead, they ask for other carefully designed strategies to help control the spread of the virus.

What do other experts think?

Professor Martin Hibberd, from the London School of Hygiene and Tropical Medicine, described testing as an important component of the public health response.

He added: “If used successfully, the data generated will be important surveillance information to understand the effectiveness of the control measures implemented.”

Meanwhile, Dr. Tom Wingfield of the Liverpool School of Tropical Medicine said he shared the concerns raised in the academics’ letter.

He added: “We do not yet have sufficient evidence on the accuracy and interpretation of antibody tests.”

A Public Health England official said that all tests in the program had been “extensively validated by manufacturers and have received CE marks,” indicating compliance with EU safety standards.

Public Health England has launched a study, using antibodies and other tests, to see if health workers develop immunity.

What about other parts of the UK?

Wales is currently working on its testing policies.

Meanwhile, the Scottish medical director has written to all health boards to tell them that they should not offer antibody tests “on demand” to NHS staff, care workers or patients.