Flu Vaccine Manufacturing
Flu vaccine is usually grown in fertilized chicken eggs. In the Northern hemisphere, the manufacturing process begins following the announcement (typically in February) of the WHO recommended strains for the winter flu season. Three strains (representing an H1N1, an H3N2, and a B strain) of flu are selected and chicken eggs inoculated.
As of November 2007, both the conventional injection and the nasal spray are manufactured using chicken eggs. The European Union has also approved Optaflu, a vaccine produced by Novartis using vats of animal cells. This technique is expected to be more scalable and avoid problems with eggs, such as allergic reactions and incompatibility with strains that affect avians like chickens. A DNA-based vaccination, which is hoped to be even faster to manufacture, is as of 2011 in clinical trials, determining safety and efficacy. Research continues into the idea of a "universal" influenza vaccine (but no vaccine candidates have been announced) which would not need to be tailored to work on particular strains, but would be effective against a broad variety of influenza viruses. On November 20, 2012, Novartis received FDA approval for the first cell-culture vaccine.
In a 2007 report, the global capacity of approximately 826 million seasonal influenza vaccine doses (inactivated and live) was double the production of 413 million doses. In an aggressive scenario of producing pandemic influenza vaccines by 2013, only 2.8 billion courses could be produced in a six-month time frame. If all high- and upper-middle-income countries sought vaccines for their entire populations in a pandemic, nearly 2 billion courses would be required. If China pursued this goal as well, more than 3 billion courses would be required to serve these populations. Vaccine research and development is ongoing to identify novel vaccine approaches that could produce much greater quantities of vaccine at a price that is affordable to the global population.
Methods of vaccine generation that bypass the need for eggs include the construction of influenza virus-like particles (VLP). VLP resemble viruses, but there is no need for inactivation, as they do not include viral coding elements, but merely present antigens in a similar manner to a virion. Some methods of producing VLP include cultures of Spodoptera frugiperda Sf9 insect cells and plant-based vaccine production (e.g., production in Nicotiana benthamiana). There is evidence that some VLPs elicit antibodies that recognize a broader panel of antigenically distinct viral isolates compared to other vaccines in the hemagglutination-inhibition (HAI) assay.
Read more about this topic: Influenza Vaccine