An antifreeze is an additive which lowers the freezing point of a water-based liquid. An antifreeze mixture is used to achieve freezing-point depression for cold environments and also achieves boiling-point elevation (anti-boil) to allow higher coolant temperature.
The strains of virus the trivalent vaccine protects against two A viruses (an H1N1 and an H3N2) and an influenza B virus. The quadrivalent vaccine adds another B virus to the vaccine which helps expand the level of protection to the recipient.
Quadrivalent flu vaccines include: 1  Quadrivalent flu shots approved for use in different age groups. 2  An intradermal quadrivalent flu shot, which is injected into the skin instead of the muscle and uses a much smaller needle than the regular flu shot. It is approved for people 18 through 64 years of age.