Commercial-Scale Flu Vaccine Produced in Cell Cultures

Vaccine processing vessel at Holly Springs, North Carolina plant (Seqirus)

21 June 2017. A vaccine developer says it produced large quantities of a current influenza vaccine for distribution to clinics and hospitals, grown in animal cell cultures rather than eggs. Seqirus, a division of CSL Limited, says the vaccines were made at its plant in Holly Springs, North Carolina, the first time flu vaccines were produced with this process on this scale.

Most flu vaccines today are grown in chicken eggs from a candidate vaccine, a process that can take months to produce in sufficient quantities to protect populations. Candidate vaccine strains are first identified by public health authorities, working with World Health Organization, then WHO generates candidate vaccine viruses that developers use to mass-produce the vaccine doses given to individuals.

Growing vaccines in eggs is needed for virus incubation and actual production before the vaccine is delivered, a process that often takes many months. As a result, WHO and other public health authorities need to identify specific influenza strains well in advance of their actual distribution, which means new strains can emerge after vaccine producers begin making doses for the public, but still before the traditional flu season. This problem occurred in 2015, when the H3N2 flu virus emerged after producers began making vaccine doses that did not cover that strain.

Growing vaccines in mammal cell cultures is already in practice to produce vaccines for polio, rubella, and hepatitis, but has been problematic when tried on a large scale for most flu viruses. The mammalian cell process makes it easier to maintain an adequate supply of production-ready cells for vaccine manufacturing, and reduce the time needed to start up vaccine production in the event of a pandemic. Clinical trials show flu vaccines grown in animal cells are safe and perform at least as well as when grown in chicken eggs.

The problem up to now was scaling-up the process to produce enough vaccine doses for mass distribution. Seqirus says it produced for the first time the H3N2 vaccine in commercial quantities with mammal cell lines, beginning with a sample of WHO’s candidate vaccine, thus completely eliminating the use of chicken eggs. H3N2 strains are part of the 2017-2018 flu virus formula. The company says it plans to use mammal cell cultures for other vaccines at its Holly Springs plant.

The Holly Springs plant was built with support from the U.S. Biomedical Advanced Research and Development Authority, or BARDA, to help combat pandemic threats. The company says the facility was designed and constructed in collaboration with WHO and Centers for Disease Control and Prevention. FDA gave its approval in August 2016 to begin producing vaccines at the plant.

Seqirus is the former vaccines division of drug maker Novartis, acquired by CSL Limited in July 2015.

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