As revealed by a new study published in Journal of Virology, annual flu vaccine can weaken children's immunity to other types of influenza virus.

Research conducted by Rogier Bodewes, DVM, and colleagues from the Erasmus Medical Center in Rotterdam unveils the potential drawbacks of annual influenza vaccination that were previously ignored.

Blood samples of 14 children with cystic fibrosis who were given annual influenza vaccinations and 27 healthy unvaccinated children were studied by the team of researchers for the presence of virus-specific killer T cells.

Studying the effects of seasonal immunisation, researchers found that unvaccinated children developed virus-specific T cells that increased with age. On the contrary, researchers discovered that unlike unvaccinated children the blood samples of vaccinated children showed no rise in number of virus-specific CD8 T cells with age.

The study authors tell that instead vaccination was discovered to interfere with induction of killer T cells in children who had cystic fibrosis and received flu treatment in the form of annual flu shots.

Referring to a previous research, the lead study author says the development of influenza A virus-specific CD8+ T cell, induced by infection, is prevented by the vaccination against the seasonal influenza A virus.

The results of the study hints that influenza vaccines, though effective against seasonal influenza, can leave patients more susceptible to infectious disease leading to a pandemic.

Citing the findings of the research, Bodewes, the lead author, says the results have accentuated the need for development of universal influenza A virus vaccines for children.

It may be noted that for past several decades efforts are being made to develop such vaccines for influenza treatment, but complexity of targeting inner proteins has been hindering the progress of research.