Influenza is a global respiratory disease with an estimated mortality of up to a half million people per year (1). The majority of traditional influenza vaccines are still produced in eggs. Downstream processing typically consists of clarification by centrifugation, concentration by ultrafiltration, and purification by ultracentrifugation (2). Recombinant vaccines are most often purified by chromatography. Chromatographic purification of viruses already has achieved major improvements in recovery and scalability (3), but it also is important because it enables virus purification to…