How do inactivated vaccines protect against infections?

Inactivated vaccines are made from pathogens that have been rendered noninfectious, often by heat or chemicals such as formaldehyde or beta-propiolactone. Because the microbe cannot multiply, it cannot cause the disease it once caused. The immune system still detects the pathogen’s antigens and creates antibodies and memory cells. Examples include the polio vaccine used in many countries and several influenza vaccines.