Safety issues
The government takes decisions about introducing a new vaccine very seriously. Vaccines would not be licensed if they were considered unsafe.
Similar flu vaccines containing a different flu virus strain (H5N1) have been clinically tested and the trials showed that these vaccines are safe and produce enough antibodies to provide protection.
Experience with seasonal flu vaccines has shown that changing the strain of virus in a vaccine does not substantially affect the safety profile of the vaccines.
But, as with any new vaccine, some very rare side effects cannot be identified or excluded until the swine flu vaccines are used in much larger numbers of people in the general population.
Outcomes of trials to date suggest that pandemic vaccines are as safe as seasonal flu vaccines.