Public health officials do not know how many Covid-19 cases 'identified' in Hertsmere are actually in the borough.

On paper, 104 cases were found in Hertsmere in the seven days to October 4 - a rate of 99.1 per 100,000 which is the fourth highest in southern England.

But Hertfordshire County Council believe a "substantial proportion" of cases in Hertsmere are university students living away from home who have not updated their address.

After the government coronavirus dashboard showed a sudden surge in cases in the borough at the beginning of this week, Councillor Tim Hutchings, cabinet member for public health and prevention at the county council, said on Tuesday this could be attributed to cases that had initially been missed by the national test and trace system.

He said: "Of these (missing 16,000 cases), 158 cases have been recorded for Hertfordshire. We believe this will show an increase in our coronavirus infection rates but, at this stage, there is no cause for undue concern.

"The main age group affected is under-35s, although cases are across all age bands, with a large number of them being students who do not study in Hertfordshire but have provided their home address here as their main place of residence."

Read previous story: Hertsmere's latest coronavirus figures 'may have been skewed by university students'

We asked the county council if they could provide any further insight into what they know about the case rate tripling in Hertsmere - with a further 13 reported on Wednesday's update.

In response to our enquiry, Cllr Hutchings said: "The additional cases, placed into the system following the national data issue, are certainly a significant contributing factor to the rise in coronavirus cases in individual districts and Hertfordshire as a whole.

"We are conducting thorough investigations in all districts which could provide greater insight into the increase in cases but, as yet, nothing has emerged which has caused a change in our approach to tackling the virus.

"In Hertsmere, we know that people in the 17 to 24 age group account for a substantial proportion of the extra cases, so inevitably some are likely to be university students.

"However, we’re unable to identify how many of these will be people not currently living in Hertfordshire. Many with universities around the UK could also be taking part in lectures online at their registered home address here.

"If a student doesn’t change their home address to their place of study, they of course will remain registered at their ‘previous’ home. It must also be recognised that cases involving those studying in Hertfordshire are also potentially affecting the figures in the same way for other areas of the UK.

"Hertsmere was, of course, taken off the government’s watchlist as an 'area of concern' last week before the additional cases were put into the system. We will continue to carefully monitor the total number of cases, in Hertsmere and right across the county.

"As ever, it’s hugely important that we all work together to stop the number of cases rising any further if we are to avoid tougher measures being introduced."

On Tuesday, the leader of Hertsmere Borough Council, Morris Bright, told us council officers had instructed Public Health England to look into Hertsmere coronavirus cases to find out whether univeristy students may have "skewed" the figures for the area.

A government map shows the majority of cases in Hertsmere between September 27 and October 3 have been people living in Radlett (21 cases), Borehamwood (16) Elstree & Aldenham (15) and Bushey Heath (12).

Some of the cases are definitely in Hertsmere - Councillor Richard Roberts, executive member for adult care and health at the county council, told the Local Democracy Reporting Service there has been a "significant" Covid-19 outbreak at a care home in Hertsmere.

In the 14 days to October 2, 25 staff members and 23 residents in care homes in Hertsmere that tested positive for Covid-19.

Data published by the Office for National Statistics shows two care home residents in Hertsmere who tested positive for Covid-19 died in the week ending September 25.