Antibody tests to detect if someone has had coronavirus will be more effective “later in the epidemic”, England’s chief medical officer has said.

Professor Chris Whitty told a press briefing he was confident that effective antibody testing could be achieved, after Downing Street said that no test so far has proved to be good enough to use.

He told reporters that tests become “more accurate as time goes by” while indicating a development timescale of a few months.

“The more accurate they are, the more useful they are going to be for us, and they will become more accurate as time goes by,” Prof Whitty said.

“The situation we’ll find ourselves in in a few months, and possibly a few weeks, will be considerably different to what we find ourselves in at the moment.

“It made a lot of sense to get started early on this, because this is clearly something which in the long run is going to be very important for how we manage this epidemic.”

In his first public appearance since recovering from Covid-19 symptoms, Prof Whitty told the Downing Street briefing that only a small quantity of the population are currently expected to have the antibodies.

This is partly due to the period of time between somebody getting an infection and antibodies being detectable.

“Most of the labs that have looked at this would say 21 to 28 days would be the kind of timescale you’d be talking about,” he added.

“They do tend to be more effective later in the epidemic.”

Prof Whitty said it was “not particularly surprising” that the initial results had not provided an effective test, because the disease is still new.

But he told the briefing that he expects the tests to improve and is confident that successful lab-based or dipstick-based tests can be developed.

It comes after Professor Sir John Bell, from Oxford University – who advises the Government on life sciences, said that those tested had so far failed.

Oxford is involved in scrutinising antibody tests that can tell people whether they have had the virus and can get back to normal life – one of the key routes out of the UK’s current lockdown.

In a blog on the university website under the header “What next?”, Prof Bell said: “We will of course continue to look for a test that meets the criteria of an acceptable test.”

We clearly want to avoid telling people they are immune when they are not

He said the search was on for a test that was sensitive and specific enough that it could be taken at home – but it will take at least a month.

Prof Bell said “large-scale testing” was a Government strategy “which will be crucial for getting us back to our normal lives in the coming months”.

He explained that long-term protection to Covid-19 comes from antibodies – “small proteins produced by your immune system that attack the virus and neutralise it”.

But he said the tests they had looked at “have not performed well”, adding: “We see many false negatives (tests where no antibody is detected despite the fact we know it is there) and we also see false positives.”

Downing Street said on Monday it will seek refunds from companies that cannot improve the failed antibody tests ordered by the Government.

“No test so far has proved to be good enough to use,” the PM’s official spokesman said.

“We continue to work with the testing companies, we’re in a constant dialogue with them and we give feedback to them when their products fail to meet the required standards.

“If the tests don’t work then the orders that we placed will be cancelled and wherever possible we will recover the costs.”