A woman who gave birth prematurely and a baby were revealed to be among the latest victims of swine flu as the number of UK deaths from the infection rose sharply.

Ruptara Miah, 39, had used a wheelchair for 15 years after a road accident but had brought up six daughters, relatives said. A statement from Whipps Cross hospital in east London, where she died said: “She was infected with pandemic H1N1. The trust can confirm that she had underlying health conditions.”

Her brother, Abdul Malik said she was admitted to hospital three weeks ago with a cough and chest infection, but her condition worsened and she died without regaining full consciousness. Her son, who was born prematurely, is being treated in an intensive care unit.

The baby who died on July 8 was less than six months old and was being treated at the Royal Free hospital, north London, on 8 July. A 70-year-old man also died at the Royal London hospital on Tuesday and an adult, whose age has not been revealed, died at the city’s St Thomas’ hospital earlier in the month. All the victims, the NHS said, “had serious underlying health conditions”. Tests are also being carried out on a seven-year-old Kent schoolboy who died on Tuesday to see if he had the virus. He suffered from other complications.

Professor Hugh Pennington, a leading microbiologist, yesterday questioned the Department of Health’s projection that as many as 65,000 people could die in the UK from swine flu. Pennington, chairman of an official inquiry into the Scottish E-coli outbreak of 1996, said: “There are all sorts of imponderables, which mean these figures are meaningless.”

He said the attack rate of 30% projected by the DoH was unlikely and he would be “very surprised” if the number of deaths came anywhere close to 65,000. “It would be a fantastically effective virus if it was doing that,” he said. “I’m surprised at the Department of Health putting out these figures in the way they have. I can understand them saying to emergency planners you have to be prepared but why are they going public in what seems like panic mode?”

Doubts over the government’s assertion that a vaccine would be available by the end of next month also surfaced yesterday. The government has ordered 132m doses, sufficient for everyone in the country. “If there is severe disease, countries will want to hang onto the vaccine for their own citizens,” said Michael Osterholm, director of the centre for infectious diseases research and policy at the University of Minnesota. About 70% of the world’s existing flu vaccines are made in Europe. The UK has ordered vaccines from GlaxoSmithKline and Baxter International , which have production plants in Germany, Austria and the Czech Republic.

“Pandemic vaccine will be a valuable and scarce resource, like oil or food during a famine,” said David Fidler, a professor of law at Indiana university who has consulted for the World Health Organisation.

“We’ve seen how countries behave in those situations, and it’s not encouraging.” The Department of Health insisted that its suppliers would honour their contracts.