Dr Guus Rimmelzwaan and colleagues from Erasmus Medical Centre in the Netherlands suggest that vaccinating children against seasonal flu may mean they do not develop natural cross-immunity to related pandemic strains.

But the suggestion was rejected in an accompanying comment article. Preventing children from catching seasonal flu far outweighs any theoretical risk of immunity to pandemic strains not developing, Terho Heikkinen and Ville Peltola from Turku University Hospital, Finland, said.

Public health decisions should be based on the best clinical evidence available, they argued.

‘There is ample evidence for the great burden of influenza in young children, and this burden appears during every influenza season,' they said.

‘By contrast, there is no clinical evidence that vaccinating children against influenza would prevent the induction of heterosubtypic immunity and thereby be disadvantageous to children in the long run.'