“Thanks to a vaccine, one of the most terrible diseases in history – smallpox – no longer exists outside the laboratory,” stated the CDC (“Why are Childhood”). The reason smallpox outbreaks or deadly cases of smallpox have not been in the news is because vaccinations completely eradicated smallpox from the world’s population. By individuals and communities taking the vaccinations for smallpox, the deadly disease no longer had any chance of spreading and taking more lives. Eradicating a disease may seem like an easy process and solution, however, there are characteristics of the disease that play a factor in eradicating diseases. Diseases that can hide in animal populations and reappear in humans are hard to find and eradicate. Another problem is when the disease has no visible symptoms. For example, “Polio causes no visible symptoms in about 90% of the people it infects” (“Top 20 Questions”). If people decide to vaccinate, this can lead to herd immunity. If the immunization levels are high enough to contain an illness, then researchers could focus more on finding the source of the disease and learn how to treat the disease. Although some symptoms may not be visible, if everyone chose to get vaccinated the world would have a better chance of the disease not spreading. When someone catches the disease and the symptoms begin to show, the doctors can approach that situation and study or examine the way the victim’s body functions and the negative factors that could have played a part in the creation and spread of the disease. UNICEF announced, “In all, vaccines have brought seven major human diseases under some degree of control - smallpox, diphtheria, tetanus, yellow fever, whooping cough, polio, and measles” (“Vaccines Bring”). One major issue of why some of these viruses are not one hundred percent eradicated is because people are choosing to opt out of the vaccinations