These preparations are called Vaccines. A vaccine is a biological preparation that provides active acquired immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing micro-organism and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins.
Answer: A positron or antielectron is the antimatter counterpart to an electron. A positron has the equal or same mass as an electron and a spin of 1/2, but it has an electrical charge of +1.