Number 10 'didn't notice' that officials stopped publishing the number of people being tested for Covid-19 each day as figure hasn't been announced since Friday last week

• Department of Health has suspended reporting the number of people tested
• This is to overcome inaccuracies caused by people being tested multiple times 
• Figure was last published on Friday, May 22, when 80,297 people were swabbed
• At least 2,144,626 people have been tested for the coronavirus in the UK so far
• Here’s how to help people impacted by Covid-19

Number 10 'didn't notice' that the Department of Health had not announced the number of people being tested for coronavirus for four days running. 

The Prime Minister's spokesman said in a briefing today that the omission of the statistic, which is usually published every day, was 'not something I have noticed'.

The last time the Department of Health published the number was last Friday, May 22, when 80,297 people were swab-tested for Covid-19. 

For the past five days the department has simply put a note saying 'Unavailable' in the section of the table it posts every day on Twitter.

Below that table officials note: 'Reporting on the number of people tested has been temporarily paused to ensure consistent reporting across all pillars.

'This is due to a small percentage of cases where the same person has had more than one test or tested positive for than once for #COVID19 in Pillar 2. 

'Corrections will be made to any figures if they have subsequently been found to have an error.'

At the last count on Friday, a total of 2,144,626 people had been tested for the coronavirus since the outbreak began.  

And today's update showed that 3,798,490 individual tests have been carried out, with 117,013 done yesterday. 

Friday's data of 3,231,921 tests carried out on 2,144,626 people suggests that, on average, one in every three people is tested twice.

There is a ratio of 1.5 tests per person, meaning every 10 people incur 15 tests, suggesting every third person gets a second test.

Being tested more than once is not unusual in medicine and increases the accuracy of tests that may otherwise fall short of a perfect standard.

Dr Paul Hunter, a former NHS doctor and now medicine lecturer at the University of East Anglia, told MailOnline it was 'valid' to retest people.

'Because the test isn’t 100 per cent sensitive, it can fail for a number of reasons,' he said.

'Some of these reasons are in the labs themselves, where there are all sorts of controls that may go wrong. Sometimes the sample comes in damaged and you have to ask if the patient can send another.

'The other issue is taking a swab. The person who does this might not do it right – for example, they might not manage to scrape against the back of the throat. '

WHAT IS THE SWAB TEST FOR CORONAVIRUS? 

Nasopharyngeal swabs are used to detect respiratory viruses, such as the flu and the new coronavirus.

It is the preferred choice for SARS-CoV-2 testing, according to the Centers for Disease Control and Prevention (CDC).

It involves inserting a long, flexible cotton bud into the nostril and along the nose 'floor'. This is supposed to be done slowly so that it is comfortable.

The aim is to reach the posterior nasopharynx, a cavity made up of muscle and connective tissue, covered in cells and mucous that are similar to the nose. It continues down into the throat.

The swab is rotated several times in order to get enough cells.

The sample is then sent to a lab, where it will be tested to determine if the patient’s cells are infected with the virus.

The coronavirus is a RNA virus, which means it uses ribonucleic acid as its genetic material. A process called reverse transcription is needed to transcribe the RNA into readable DNA.

A swab sample doesn't collect much RNA in one go, therefore a polymerase chain reaction (PCR) is used to rapidly make billions of copies so it can be analysed.

The DNA is dyed a fluorescent colour, which glows if the coronavirus is present, confirming a diagnosis.

One of the main reasons for multiple tests is likely to be because doctors don't want to misdiagnose someone as having - or not having - the virus.

If someone is hospitalised with coronavirus symptoms and lives with someone else who has tested positive, for example, they would be retested if their first swab comes back negative. 

Dr Hunter said: 'It may be that someone has symptoms synonymous with coronavirus – they have a sore throat and fever which has come on suddenly.

'If this patient’s test comes back negative, the clinician might think something went wrong or “I better test them again just in case”.

'I personally wouldn’t criticise the Government for including repeat swabs in their daily count. 

'But it should only include swabs that have been examined in the laboratory – not swabs that are posted to people.'

Swab testing is usually carried out by a medical worker pushing a long cotton bud through someone's nostril into the top of their throat.

It can be an uncomfortable procedure and it can be tricky to get the right types of cells on the end of the swab.

The coronavirus is most present in the epithelial cells in the airways, which can be found in the airways at the back of the nasal cavity, therefore the swab must be inserted deep into the nose and moved around. 

The sample is then sent to a lab, where it will be tested to determine if the patient’s cells are infected with the virus. 

Access to swab tests has now been extended to allow some people to take their own samples at home and return them to the Department of Health by post.

Some of these may need to be redone because people aren't qualified to do the tests properly and may not carry out a thorough enough swab.