Health experts have admitted they now have no idea how many people in Hertfordshire have contracted swine flu.

The admission comes after officials today confirmed the county has abandoned a policy of “containment”, as the swine flu epidemic continues to spread.

Suspected cases are no longer being tested in laboratories and instead, GPs are now prescribing anti-virals to anyone displaying flu symptoms.

Doctors in Watford, Three Rivers and Hertsmere have been following a similar policy since the boroughs were all declare swine flu “hotspots” more a week ago.

The move is part of a national shift from a “containment phase” to a “treatment phase” of the H1N1 strain of the influenza bug. It means it is now impossible for health experts to say how many people have caught the virus.

A statement from Hertfordshire's Primary Care Trusts confirmed, as the Watford Observer reported last week, that schools will not now close if they have cases of swine flu.

The statement said schools will now only close if there are “special circumstances” or if there are too many staff absent for the school to keep running.

Parents have also been asked to ensure children stay away from school if they do develop the illness.

Despite admitting the number of swine flu cases is now unknown, officials say the virus has not had a significant impact on businesses or services.

Dr Jane Halpin, director of public health in Hertfordshire, said: “The approach we have taken up to now has been helpful in slowing the spread of swine flu but as there is now a significant level of transmission it is appropriate to make these changes and put in place the mechanism within the county to make sure people who do contract swine flu are treated promptly and appropriately.

“As the number of cases has been rising, we have been continuing preparations so that we can continue to provide this service and we have also been planning for vaccination in due course.

"We will be increasing our focus on this work in the coming weeks.”