Vaccines in cultured cells
An alternative way of producing influenza virus for vaccine production is based on the use of cell cultures in a biological fermentation process. Mammalian cells are usually used for this purpose. The cells are infected with the virus and the virus is left to multiply for several days. During the course of this process, most of the cells die. The virus is then separated from the cell residue, purified and inactivated via a chemical process. This production method is still not used for large-scale production, although some cell culture based influenza vaccines have now been licensed. It may be expected that cell culture based influenza vaccines will be used extensively in the near future. The major advantages over egg-based vaccines are that the procedure is more flexible and independent of embryonated chicken eggs. Cell culture based systems could more easily be scaled up in times of a pandemic, although obviously also for this type of production system adequate planning is of key importance: the up-front costs for operational readiness of production plants with huge fermenters are definitely not negligible.