Partners, Researchers & Academics

 Vaccine development entails a rigorous system from identifying candidate molecules, testing in the laboratory, controlled testing in a few human volunteers, controlled testing in a big population and routine adverse event monitoring when vaccines are licensed for wider use.  If the vaccine triggers an immune response, then it is tested in human clinical trials in three phases. Phase 1: small number of volunteers to assess its safety; phase 2: several hundreds of volunteers to further assess safety and ability to generate an immune response. Participants in this phase have the same characteristics (age, sex); Phase 3: thousands of volunteers are compared to a similar group that received a comparator product. Often, this trial is conducted in multiple countries and multiple sites. Read more :Health product policy and  standards (who.int)

Collective immunity or herd immunity or community immunity refers to a situation whereby a high number of individuals in a given community are immune against a given infection thus making transmission between individuals less likely. The reduced likelihood of transmission between individuals protects even the non-immune due to the reduced chances of getting into contact with an infected person. 

Vaccines greatly reduce or eliminate many infectious diseases that are harmful to children, and adults. Viruses and bacteria or their new variants that cause disease still exist. Some have been controlled to low levels but still have the potential to spread if the number of non-immune persons increases. For this reason, vaccination against a disease of public health importance is necessary until such a disease is totally eliminated.