In this article, we are going to list the 15 largest vaccine companies in the world. Click to skip ahead and jump to the 5 largest vaccine companies in the world. Vaccination is the most simple and effective way of prevention of many diseases. It provides immunity to infectious diseases and it is the most cost-effective method to protect the world population. The first-ever vaccine was introduced for smallpox to treat the deadly cowpox virus in 1796. This virus killed many people and developing a vaccine for it saved many lives. But the concept of vaccines existed even before 1796. Pharmaceutical companies around the globe have worked to develop vaccines for diseases such as Malaria, HIV, cholera, influenza and tuberculosis.