Final answer:
The inactivated influenza vaccine is grown in chicken eggs and treated with chemicals to render the virus noninfectious before purification and packaging for injection.
Step-by-step explanation:
The inactivated form of the influenza vaccine is grown in chicken eggs. The influenza virus particles are cultured and harvested in this environment, after which they undergo a chemical treatment to ensure they are noninfectious. The crucial part of this process is the use of chemicals such as formalin, beta-propinolactone, or an imine which inactivate the virus without compromising its immunogenicity — its ability to provoke an immune response. The resulting inactivated virus particles are then purified and packaged for administration as an injection. This type of vaccine is different from live attenuated vaccines, which are created by weakening the disease-causing virus so that it cannot cause serious illness but still elicits an immune response. However, live vaccines carry a risk of back mutations that might allow them to revert to a more virulent form.