Smallpox is the only disease in the world that has been eradicated and while polio is close behind, herd immunity alone can’t help from eradicating it.

Getting vaccinated is the key method of eradicating diseases.

Herd immunity is the result of getting a combination of vaccines, such as the flu shot or the MMR vaccine. Dr. Robert Frenck is a professor of pediatrics in the division of infectious diseases at Cincinnati children’s hospital. 

“It’s almost like putting a bubble or a protective layer around a person that wasn’t immune by having all these people around them that are immune,” Frenck said of his definition of herd immunity. 

Dr. James Cohen, who works in the emergency department at the Cleveland Clinic said an index is extremely important in this situations. 

“An index case is the first case so if you can prevent a contagious disease in the first case by definition you’ll prevent all cases,” he said. “It’s like a firewall.”  

Cohen also said that anyone with a comprised immune system is at risk. 

“Anybody with any heart, lung, liver or kidney chronic disease would be susceptible, immunocompromised,” Cohen said. Also, those who are elderly, diabetic or HIV/AIDS, cancer and transplant patients.

Cohen said that the false theory of vaccines causing autism has gained traction. It’s a mindset that deters people from vaccinating their kids, therefore causing an outbreak.

Although, he has treated people with Guillain-Barre Syndrome, an autoimmune disorder which can be associated with the flu shot. However, the National Institute of Neurological Disorders and Strokes said “In rare instances vaccinations may increase the risk of GBS.”

With parts of the country not vaccinating, outbreaks of diseases are likely to occur. For example, Frenck said a measles outbreak occurred in an Amish community near Columbus, some of the community members went on a mission trip to the Philippines, contracted the measles and brought it back to Ohio. Because of the lack of vaccinations and herd immunity, everyone in the community was susceptible to the disease.

With the lack of vaccinations, more outbreaks of preventable diseases are likely to occur. For instance, Frenck said there are hundreds of cases of measles per year and thousands of cases of whooping cough per year.

“Herd immunity will only last until — as long as you continue to vaccinate,” he said. “The only way that you can stop vaccinating is if you totally eliminated the infection.”

“We’re getting closer with polio, we’re hoping in the next few years that we’ll be able to eliminate polio from the world,” Frenck said. Mossad said the disease is eradicated in the western hemisphere, however, the disease exists in countries like Nigeria, Syria and Pakistan.

Cleveland Clinic’s Dr. Sherif Mossad, said it all comes down to getting vaccinated. 

“We do not know who is going to be exposed, so we cannot rely on herd immunity, we all have to get the vaccine,” Mossad said.

Anu Sharma is a health reporter. Contact her at [email protected].