A technical glitch may be artificially inflating the number of Covid cases in Hertfordshire by more than 30 per cent - by wrongly recording the location of students with the virus.

New data suggests that hundreds of Hertfordshire students have already tested positive for the virus since moving away to universities and colleges elsewhere in the country.

But instead of being attributed to their new address, it's believed their test results have been wrongly registered as cases in Hertfordshire.

Data – collected over a seven-day period at the beginning of this month – suggests that, as a result, the number of Covid cases in Hertfordshire could have been inflated by a third.

And that means data collected in university towns and cities could be failing to reveal the whole picture there too.

The issue was highlighted at a meeting of the county council's public health and prevention cabinet panel on Wednesday, by director of public health Jim McManus.

At that meeting Mr McManus suggested to councillors that the issue was the result of the NHS Digital 'enrichment process', which was over-riding the addresses that had been supplied by students.

"There is a thing called the NHS Digital enrichment process, where laboratory data is run through to find missing contact details," he said.

"Now that is entirely sensible – it happens at a national level – it's not us that do it, it's NHS test and trace.

"But it appears that national database is over-riding addresses that may have been provided by the individual at the test centre.

"So if a Hertfordshire resident went to Newcastle University – even if they provided their Newcastle Uni address at the time of the test it may be over-ridden if their Hertfordshire address is on the NHS 'spine'."

As well as impacting on the number of cases attributed to the county, Mr McManus said it would impact on 'contact tracing'.

And Mr McManus said there had been times in Hertfordshire when contact tracers had attempted to reach a person – only to be told by their parents that they were away at university.

But he stressed that the findings were based on data from a single week – and that it was not yet known whether the pattern would be replicated across other weeks, after October 1.

"I hasten to add this is one week's worth of data," he told councillors.

"I hasten to add that we don't know if this pattern is replicated across other weeks.

"I hasten to add this is a national challenge – but you can see that it makes a material difference not only to our numbers but also to contact tracing."

According to the data for the seven-day period (ending October 1) there were 715 Covid cases reported for Hertfordshire, based on addresses on the NHS database.

But analysis of the results suggests that 242 of those 'Hertfordshire' residents were living elsewhere at the time of the test, such as a term-time university residence.

The breakdown of the data suggests that 23 of the cases recorded for north Herts including Hitchin, for that week were living at 'alternative postcodes'.

Mr McManus outlined the situation as part of an update on the coronavirus local outbreak plan to a meeting of the county coucil's public health and prevention cabinet panel on Wednesday.

He also reported that there were currently 23 Covid patients in one Hertforshire hospital alone – with two needing ventilator support.

And he said that there had been three deaths in the county in the last seven days and one in the week before that.

The 'R' number – which indicates the average number of people an infectious person passes the virus on to – was reported to be estimated to be up to 1.3 in the East of England. A number below one suggests the virus is shrinking – and above one that it is growing.

And Mr McManus said: "Our aim is if we can to keep the virus as low as possible and keep normal life.

"That will only happen if our residents keep doing the amazing work they have been doing – but also if we make sure that we deal effectively with situations where there isn't compliance, as well as getting all the measures in place we need to in case it does go higher."