One of the most significant impacts of the germ theory was the development of vaccines. The theory provided the scientific basis for understanding how the body responds to pathogens and how vaccines could be used to stimulate immunity without causing the disease itself. Louis Pasteur's work led to the creation of vaccines for rabies and anthrax, and his development of pasteurization—a process to kill harmful bacteria in liquids such as milk—demonstrated the importance of controlling bacterial infections.

As knowledge of germs spread, the creation of vaccines expanded to prevent other infectious diseases, including smallpox, polio, measles, and later, diseases like hepatitis B, HPV, and COVID-19. Vaccination has remained one of the most effective ways to reduce the burden of infectious diseases worldwide.

With the understanding that bacteria and other microorganisms could cause infections, the medical field developed new methods for controlling germs, particularly in hospital settings. The discovery of germs led to the widespread adoption of sterilization techniques in surgery, wound care, and medical equipment cleaning.

Joseph Lister, an English surgeon, is credited with pioneering the practice of antiseptic surgery, using carbolic acid to sterilize instruments and disinfect wounds. This drastically reduced surgical infections and mortality rates, improving patient outcomes and making surgeries safer.

The sterilization of medical equipment, and the requirement for aseptic techniques (maintaining a sterile environment), are now standard practice in hospitals and healthcare settings worldwide.

The germ theory of disease also paved the way for the discovery and widespread use of antibiotics. The accidental discovery of penicillin by Alexander Fleming in 1928, following his observation that a mold called Penicillium killed bacteria, marked the beginning of the antibiotic era. This discovery was made possible by the understanding that bacteria could cause infections in the body and could be targeted by specific drugs.

Since then, antibiotics have revolutionized the treatment of bacterial infections, saving millions of lives from diseases like pneumonia, tuberculosis, and sepsis. The development of antibiotic resistance is a current challenge, but antibiotics remain one of the most effective tools in combating infectious diseases.