The seed virus is a safe form of the influenza virus, stripped of its parts that spread the infection

-Then the live virus is genetically altered to make it safe. This is a time-consuming process and takes about three-four weeks. This seed virus is supplied to vaccine manufacturers chosen by the World Health Organisation around the world

-The seed viruses from various strains are then prepared to be ready for vaccine production by a process called 'assortment.' These re-assorted viruses are then injected into specially prepared pathogen - or germ-free - fertile chicken eggs

-The safe virus then grows inside the eggs for four-six weeks. The viruses are then extracted from the eggs, purified, inactivated and then formulated into a vaccine

Serum Institute in Pune has already received the seed viruses, even as the H1N1 strains have been extracted from infected patients in India and Turkey.

Thankfully, the experts have found that the viruses are identical, indicating that the new vaccine should work against the swine flu that has spread to all these regions.

The normal dosage of influenza vaccine is 15 mg. From each chicken egg, one dose of influenza vaccine is produced. Sometimes, two eggs may be required to produce each dose of standard influenza vaccine.