Cases of flu appear to be falling across England and Wales but experts said they might rise again.

The latest data from the Royal College of GPs suggested the number of cases per 100,000 people had fallen in the past week from 68.5 to 41.3. Cases of the common cold have also dropped from 355.3 to 184.7.

A spokeswoman for the college said it was unlikely flu would hit a nine-year high as predicted. But Professor Steve Field, the college chairman, said people returning to work and school could easily spread flu and the vomiting bug norovirus. "GPs are coping and this is by no means a crisis. But I think a lot of people are looking to us because they want a sick note," he said. "My prediction is that people are coming back to work or school and they are circulating influenza and transferring it to each other. We think cases of flu and norovirus will go up again."

The Department of Health said: "There is always more demand on health services in winter and during the cold and flu season and this year is no exception. The NHS is well prepared and it is coping." But Geoff Martin, of the Health Emergency campaign group, said the return to work this week would prove "heavy going" for the NHS.