Companies hit hard by staff illness may be reviewing their business insurance needs as the New Year draws closer.
According to the Royal College of General Practitioners, cases of flu have risen by almost 50 per cent in the last week.
This includes both seasonal flu strains and the H1N1 swine influenza virus.
In the week up to Christmas, there were 124 people in every 100,000 suffering with flu, compared to 86 per 100,000 the previous week.
An increase in flu cases was seen across all age groups, except children. However, experts believe this could change once youngsters return to school.
Flu can hit businesses hard when staff are forced to take time off due to illness.
A possible increase in cases among children in January could have a further impact as parents stay at home to take care of sick offspring.
Despite the sharp increase in flu cases, levels have still not reached epidemic proportions, which experts describe as affecting 200 per 100,000 people.