Small correction: it means you get 95% fewer cases. People might still get infected, but never show enough symptoms to prompt them to get tested - and therefore never become a "case." This is the difference between "protective" (no disease) and "sterilizing" (no infection) immunity. The latter is the gold standard that you'd ideally like to shoot for, but the former is what the studies are actually measuring.
The distinction matters because there are vaccines (such as the original polio vaccine) that protect individuals against disease, but which still allow the vaccinated individuals to act as carriers and infect others. Those vaccines do not create herd immunity, because vaccinated people still contract and spread the virus. They do, however, protect the people who get vaccinated.
The distinction matters because there are vaccines (such as the original polio vaccine) that protect individuals against disease, but which still allow the vaccinated individuals to act as carriers and infect others. Those vaccines do not create herd immunity, because vaccinated people still contract and spread the virus. They do, however, protect the people who get vaccinated.