A flu vaccination ban for kids has been lifted for two flu vaccines, Vaxigrip and Influvac, following a series of adverse reactions from the influenza immunization earlier this year.

Close monitoring of the side effects has revealed that convulsions seemed to be related to Fluvax, a flu vaccine manufactured by CSL, says Professor Jim Bishop, chief medical officer of Australia.

Local and international investigations using seasonal flu vaccines, Vaxigrip and Influvac found nothing higher than normal incidence of convulsions among children under five, says Prof Bishop.

Although, there is still no possible explanation to explain the higher than expected observed rates of fever and febrile convulsions, with Fluvax, Prof Bishop says, the investigations are continuing.

He advises parents of children less than five years of age to discuss with their GP or vaccine provider regarding flu vaccination of their children, using Vaxigrip of Influvac.

In the meantime, I am now advising that if parents of children under five years of age wish to have their children vaccinated against seasonal flu that they should discuss with their GP or vaccine provider the use of Vaxigrip or Influvac, says Prof Bishop.

He also warned that influenza itself can cause fever in young children that can trigger adverse reactions.

According to Darryl Maher, medical and research director of CSL Biotherapies, the company's team of scientists continued to work with TGA to determine the cause of febrile convulsions connected with Fluvax.

Dr Maher said the company supports a precautionary approach to the use of its influenza vaccine in children while they continue to investigate the cause of the unexpected increase in febrile convulsions.

He stated that CSL manufacturing processes have not changed and the previous seasons have never had high incidence of the adverse reactions related to the use of their influenza vaccines.