It is understood there has been a higher rate of fever in young children following a second injection.

BBC: Change to swine flu jab advice

Both children had a fever and cough in late March, and one child vomited.

CNN: CDC: Swine flu seen in 2 California children

Some strains of the bacteria can cause severe diarrhoea, abdominal cramps and fever, and can cause fatal kidney failure in children.

BBC: Men caught in Southampton harvesting 'poisonous' clams

If you have symptoms for under 48 hrs, there are antiviral medications (Tamiflu and Relenza) that may reduce the duration of symptoms including fever, as well as potential complications (pneumonia, otitis media in young children).

FORBES: 2013 Flu Season: How to Protect Yourself