NHS trusts were given two days notice to carry out thousands of antibody tests ahead of the Government's target of boosting testing capacity to 200,000, it has emerged.
Pathology labs were asked to take part in the last-minute scramble as part of efforts to rapidly expand testing.
On Sunday, health officials said capacity had reached 205,634 a day earlier, including the ability to carry out 40,000 antibody tests a day for NHS and social care workers.
That meant officials could claim success on promises to reach capacity for 200,000 daily tests a day before their June 1 target.
It has now emerged that NHS England and Improvement wrote to health service leaders last Wednesday – when the UK had capacity for 161,000 tests – giving them until last Friday to carry out thousands of antibody tests.
Regions were typically told to deliver around 6,000 tests each in order to boost capacity by 40,000 in 48 hours. Antibody tests aim to establish whether a person has previously had coronavirus.
Ultimately, it is hoped that such tests could show that a person is protected from getting the virus again – but it is currently known neither how much immunity is conferred nor for how long.
This means that, even if doctors and nurses are told they have developed antibodies, it will not make any difference to the work they are asked to do. NHS trust managers said there was currently no way for them to use the information.
One NHS head of pathology told Health Service Journal: "There is one obvious answer as to why there is suddenly such an urgency to roll this out. While it will be interesting to have the results, there is nothing meaningful we can do with this test data at the moment."
Another trust director described the antibody tests as having "no clinical value".
A senior figure involved in the testing programme said that the drive to roll out the antibody tests was driven by the "need to do something" with them after the Government announced plans to buy 10 million.
National NHS officials have said the rollout of antibody tests will "provide information on the prevalence of Covid-19 in different regions of the country and help better understand how the disease spread".
A letter sent to NHS trust managers in the south-east on May 27, asking them to deliver 6,000 tests a day by May 29, said the data will also be used for research.
A spokesman for the Department of Health and Social Care, which is responsible for the testing programme nationally, said: "Antibody tests, including those used by the ONS, have always contributed to the daily capacity figure and it is misleading to suggest they have been rushed out to hit a target.
"We are rolling out millions of antibody tests to help us to better understand the level and duration of immunity and how the virus is spreading across the country."