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 and High Dose flu shots are available at CVS Pharmacy and MinuteClinic High-dose vaccine: developed for people over 65 years old; contains the same 3 virus strains as the trivalent vaccine but four times more potent than the traditional flu shot; Is one flu vaccine recommended over another? The CDC doesn't recommend one vaccine over another.