The number of new swine flu cases has risen by almost 50% in the past week, government figures showed today, although the level remains below that seen at the peak of the virus's spread in the summer.

There were an estimated 78,000 new cases of swine flu in England in the past week, up from 53,000 in the week before – which in turn was double the number in the previous week, meaning the rate of increase has declined.

The weekly tally is also still below the 100,000 weekly cases at the peak of swine flu in July.

There are currently 751 people in hospital with the virus, of whom 157 are in intensive care. The number of swine flu deaths in England now stands at 97.

While the number of cases in the summer outbreak declined steeply, there was a widespread presumption that the H1N1 virus would again spread rapidly with the onset of winter, when seasonal flu outbreaks tend to peak.

During the lull, plans were rushed through for a mass vaccination programme against swine flu, which was launched eight days ago, targeting 11 million priority patients and frontline health workers in its initial phase.

The US president, Barack Obama, last week declared a national emergency in America over swine flu, although health officials described this as mainly a precautionary measure.