Immunization Information

Why do we need vaccines?

Vaccines are important because they keep people healthy. People used to get sick and die from diseases we now prevent. Today’s new parents are generations removed from the pandemics (widespread infection) of the past, and kids today thankfully do not have to worry about many once-common illnesses. Care and attention to keep these diseases in check, and routine vaccination is still necessary.

Vaccines are safe and can safely be administered to nearly everyone. But “nearly everyone” still means that some people can’t get vaccines. There are some people whose immune systems have been weakened, either by disease or medications, and their bodies cannot fight off infection or generate a response to a vaccine. These people rely on everyone else to get vaccinated to reduce the amount of disease circulating in the general population, so they do not get exposed to the disease and get sick.

What is herd immunity?

Herd immunity, also called community immunity, is the immunity that an entire population gets against a disease, even though each individual may not be immune.

This is possible because if more members of a community are immunized, fewer viruses and bacteria are able to spread through the community and infect those who are not immune (15). When vaccination rates fall below a critical point (85% to 95% for most vaccine-preventable diseases), people who are not immune to the disease start getting sick (16). Some members of the community cannot get a vaccine for medical reasons, such as an allergy to a vaccine component, medical conditions like cancer or an immune deficiency, or immunosuppressive medical therapy. For these individuals, herd immunity is the only immunity they have (17, 18).

Is herd immunity a thing? Is community immunity real?

Yes, herd immunity is a thing – and it’s backed up by some pretty neat math (15). Herd immunity, also called community immunity, is the immunity that an entire population gets against a disease, even though each individual may not be immune. This is possible because the more members of a community who are immunized, the less viruses and bacteria are able to spread through the community and infect those who are not immune (15). When vaccination rates fall below a critical point (85 to 95% for most vaccine-preventable diseases), people who are not immune to the disease start getting sick (16). Some members of the community cannot get a vaccine for medical reasons, such as an allergy to a vaccine component, medical conditions like cancer, an immune deficiency, or needing to have a medical treatment that suppresses the immune system (immunosuppressive medical therapy). For these individuals, herd immunity is the only immunity they have (17, 18). If you want to see the statistics of herd immunity in action, here are some online simulators: