Influenza is an infection of the respiratory tract caused by influenza virus. It involves a combination of respiratory (cough, sore throat) and constitutional (fever, headache, muscle aches) symptoms. In Children, older adults and people with a range of pre-existing medical conditions influenza infections can lead to serious and even life threatening complications.
As the circulating viruses change by mutation infections can occur repeatedly throughout life and protection by vaccination requires annual dosing with updated vaccines. Seasonal vaccination prevents influenza and reduces the impact of epidemics.
Each year in February the WHO makes a decision on the influenza strains to be included in the following winter's vaccine for the Northern Hemisphere, and in September for the Southern Hemisphere. The WHO Collaborating Centers then release suitable primary seed virus to the manufacturers, like Tianyuan. These primary seed viruses currently comprise three influenza virus strains.
In Tianyuan's production facility, each of these strains ¨C one A-H3N2, one A-H1N1, and one B strain ¨C are separately propagated in SPF hensĄŻ eggs to produce larger amounts of the viruses which serves as source for the production of virus batches on an industrial scale.
The production of YUGANNING starts with the inoculation of the virus into the allantoic fluid of healthy chicken embryos, where it multiplies. After a certain period of incubation the virus is harvested, inactivated and purified using different downstream processing techniques. The purified whole virus is then split, using a detergent and further purified to yield the so-called monobulk. These production steps are applied separately for each of the three vaccine components.
In the last step, the components are blended in the correct proportion, and the mixture is filled into syringes or vials of 0.5 ml for adults and 0.25 ml for children. A syringe or vial contains one dose of trivalent influenza vaccine in the required amount of 15 µg HA per strain for adults and 7.5 ug HA for children.
Finally, the vaccine quality is checked and then marketed after approval by the national regulatory authority (SFDA). The product is in compliance with the EU standard.
Tianyuan's influenza vaccine YUGANNING is an inactivated split vaccine, produced on embryonated chicken eggs. The vaccine is manufactured according to the seasonal WHO recommendation for Northern and Southern Hemisphere. The vaccine's quality level is comparable to internationally available vaccines.