Flu cases rise over Christmas break
There was a slight rise in cases of flu over Christmas, however, the real number may be higher as many doctor's surgeries closed on bank holidays.
Health Protection Agency data showed 33 per 100,000 people in England visited their GP about flu last week. Up from 27 per 100,000 the week before.
Also, a higher proportion of calls to NHS Direct were about flu.
Flu symptoms include a sudden fever, a cough with a sore throat, and aching muscles and joints.
Prof John Watson, from the HPA, said: "Over the Christmas period we have seen a slight rise in flu activity across several of our indicators in line with the trend we expect to see at this time of year.
"However, the latest data should be interpreted with caution due to GP practices being closed on the bank holidays which may have impacted on GP consultation rates.
"It is vital that those who are most 'at risk' from flu make sure they receive their vaccination as this is the most effective way of preventing them from becoming ill with the virus."
At risk groups include the over-65s, pregnant women, people with weakened immune systems and other health conditions.
There was also a rise in cases of the winter vomiting bug, norovirus, in the last week of 2012.
The combination of the festive period and a large number of norovirus cases has led to call for more people to donate blood due to a shortage of supply.
A Department of Health spokesperson said: "The NHS is experienced in dealing with the extra pressure the winter period can bring every year and is coping well so far this winter.
"To try to reduce the spread of flu and other winter bugs, we have launched the 'Catch It. Bin It. Kill It' campaign.
"It reminds us that we can all play a part in limiting the spread of flu by washing our hands and throwing away used tissues to prevent the spread of viruses."