Ten people are being treated for swine flu in critical care units across Coventry and Warwickshire, NHS Warwickshire says.
There are two cases at George Elliot Hospital in Nuneaton, two at Warwick Hospital and six are being treated at Coventry's University Hospital.
Flu cases have more than doubled in the past week in England and Wales, according to new figures.
People with flu-like symptoms are asked not to visit friends or relatives.
Those in high-risk groups, particularly pregnant women, are being urged to get vaccinations to protect against both seasonal flu and swine flu.
Figures from the Royal College of GPs show cases have risen to 87.1 per 100,000 people, from 32.8 in the previous week.
However, the number of cases this year is much lower than the number of people catching flu at the height of last summer's swine flu outbreak.