Science in Blood Donation Act of 2020 This bill requires the Food and Drug Administration (FDA) to revise its guidance on reducing the risk of transmitting by blood transfusion human immunodeficiency virus, hepatitis A, and hepatitis B. Specifically, the FDA shall update its guidance to remove recommendations to not receive blood donations from a man who had sex with another man in the past three months. The FDA shall also remove recommendations to not receive blood donations from a woman who in the last three months had sex with such a man. The FDA's updated guidance shall be based on an individual risk assessment of sexual behaviors that evaluate all donors equally without regard to sexual orientation or gender identity.