Due to the high rate of mutation of viuses, hundreds of subcatagories of flu types are in the air. New vaccines are created every year to combat the most common strains for the new season. Melvin Sanicas explains flu vaccines and why they people need a new flu shot every year.

This clip expains herd immunity and the possble routes to achieve it.

Hank explains adaptive immune systems and how they function to fight against pathogens ny creating antibodies.

Hank explains innate immune systems and how the signs that we may associate with sickness are actually be symptoms of your immune system working.

Hank explains how the cellular immune response uses helper, cytotoxic, and regulatory T cells to attack body cells compromised by pathogens.