Vaccines not only keep individuals healthy, they also help keep communities healthy. However, when vaccination rates in communities fall below the needed levels for “community immunity” (also known as “community protection” and “herd immunity”), infectious diseases that we no longer see as often in this country can easily come back, causing vulnerable people of all ages to get seriously ill. If we stop vaccinating in the U.S., we could easily have tens or hundreds of thousands of cases of diseases.
Many infectious diseases are no longer as common in the U.S. as they once were, but in today’s interconnected world, diseases are often just a plane ride away. Measles is still common in many parts of the world including some countries in Europe, Asia, Africa and the Pacific. According to the CDC, worldwide, about 20 million people get measles each year, and about 146,000 of those people will die of the disease.
Although measles no longer naturally occurs in the United States – unvaccinated people continue to get measles while traveling abroad, bring the disease into the U.S. and spread it to others.
The U.S. has experienced a large number of measles cases so far this year. According to the CDC, in 2019, 1,250 cases of measles were reported from 31 states.
Recent outbreaks of several other vaccine-preventable diseases have also caused serious illness and even death among people of all ages in the United States. There have been multi-state outbreaks of hepatitis A among various populations including the homeless and drug users, and universities in the U.S. continue to experience outbreaks of mumps (defined by CDC as 3 or more cases linked by time and place) and meningococcal serogroup B disease, requiring outbreak control efforts including the vaccination of thousands of students.
Whooping cough (also known as pertussis) remains a common disease in the U.S. with frequent outbreaks, and has infected nearly 100,000 people here since 2014. If we didn’t vaccinate against pertussis, there would be many more cases of this disease, which is very dangerous for infants. In most cases, whooping cough is spread to babies from close family members, which is why all close contacts of infants and pregnant women should be vaccinated with a vaccine containing pertussis. (DTaP or Tdap).
Flu, cancer-causing HPV, hepatitis, and many other vaccine-preventable diseases continue to circulate here in the U.S., placing our loved ones in danger. Read more about outbreaks of vaccine-preventable diseases in our Questions about Vaccines section.