Extra supplies of anti-viral drugs are expected to arrive in the South West this weekend to prepare for any more confirmed outbreaks of swine flu.

Dr Gabriel Scally, director of public health for the region, said the Government had been stockpiling a large amount of the medication as a precaution in case of a pandemic.

It is held in various depots around the country and supplies are now being distributed more locally so they are more easily available.

Dr Scally said the Health Protection Agency (HPA) in Bristol had also brought in extra staff to handle the large number of calls from people with concerns about the illness and to provide them with reassurance.

He said he was pleased with the way the outbreaks so far were being handled, with the spotlight on the South West because of the three confirmed cases in the region - two of them in South Gloucestershire.

They include a 12-year-old girl pupil at Downend School, who had returned from a holiday in Mexico, and 43-year-old Barry Greatorex, of Chipping Sodbury.

Mr Greatorex believes he developed the illness because he had been in the same office in the East Midlands as a colleague who had also been holidaying in Mexico.

Although the woman had been suffering with some symptoms, including a cough, Mr Greatorex said she had tested negative for swine flu.

Dr Scally said: "That is an unusual situation but she may have recovered from it by the time she was tested. I understand further tests are being carried out and we now await the outcome of those tests.

"It's impossible at this stage to say Mr Greatorex definitely got the virus from his colleague but on the balance of probability it is likely."

Dr Scally said there was no sign of panic among the public in response to the confirmed cases.

He said: "The public understand very well what we are doing and I'm very pleased with the way the NHS has responded to these cases."

He said hundreds of leaflets had been given to parents and pupils at Downend School and anti-viral drugs distributed at levels that were lower than for someone with the virus.

Dr Scally said: "The lower dose is 70-90 per cent effective in stopping the development of influenza.

"We will know in the next couple of days whether we have been successful in interrupting the transmission.

"The NHS response is very vigorous and the cases so far have been fairly mild We are being so active because we want to contain the virus."

Sheila Cook, the executive councillor for children and young people on South Gloucestershire Council, said any decision to close a school as a result of swine flu would be taken by the HPA.

She said: "It's not down to the local education authority to make that decision. It's totally in the hands of the agency."

Downend School has been closed until Monday, May 11, and will undergo a deep clean while it is shut.

As Mr Greatorex's 13-year-old son, Jamie, has not shown any symptoms of the illness, it is thought unlikely that other students at Chipping Sodbury School, where he is a pupil, will have to be treated with medication.