Based on the experience from recent evaluations of annual update applications for influenza vaccines (inactivated), both regulators and industry have requested further guidance about the regulatory requirements of HI testing as applied for the qualification of influenza seed virus preparations. Whilst some of the principles outlined below may be applicable to live attenuated influenza vaccines (LAIV), there are additional considerations towards the qualification of seed virus preparations using HI testing and hence LAIVs are outside the scope of this Q&A document.
Keywords: influenza vaccine (inactivated), Haemagglutination inhibition, seed virus