The country's first swine flu vaccine trial is being carried out, it has been revealed. Some 175 people have enrolled in the trials at the Leicester Royal Infirmary (LRI).

The results of the trial, which is testing different doses of the vaccine, may be available in four to six weeks' time, a statement from the University Hospitals of Leicester NHS Trust said.

It comes as it was confirmed that ministers are considering plans to immunise every schoolchild in the UK against swine flu. If the plans are agreed, it would be the biggest mass vaccination since pupils were given jabs against smallpox in 1964. There are 8.5 million pupils aged five to 16 in the country.

The Department of Health stressed that no decision had been made on delivering the vaccination. But a spokesman for the Department for Children, Schools and Families confirmed the proposals were being considered.

As part of the vaccine tests, led by Dr Iain Stephenson, consultant in infectious diseases at the LRI and a clinical senior lecturer at Leicester University, volunteers receive two shots of the vaccine, and their blood will be tested to show their levels of immunity. The trial will also establish how far apart the dose needs to be given.

New government figures show the numbers of people being diagnosed with swine flu dropped from 110,000 to 30,000 over the past seven days. But there have been nine new deaths related to the virus in the last week, and 36 people have now died.

Dr Stephenson told the Leicester Mercury there was nothing experimental about the vaccine as it was produced in the same way as seasonal flu vaccine. He said: "It is only the 'swine flu' part that is different."

The chief medical officer, Sir Liam Donaldson, said this week there was no evidence that the virus was mutating or developing a resistance to medication. But he urged against complacency and predicted a "second wave" would hit the country in the autumn.