Is herd immunity impossible?

After Pennsylvania Governor Josh Shapiro talked about 95% of people in the community getting vaccinated to have herd immunity, Brian Hooker posted a rebuttal video. In it, he claims that herd immunity cannot work because no vaccine provides perfect protection. He also says the 95% MMR vaccination goal is impossible and that outbreaks will still happen in highly vaccinated communities.

• Community immunity makes it harder for contagious diseases to spread.
• It protects vaccinated people and those who cannot be vaccinated.
• Vaccines do not need to work perfectly for community immunity to help.

Herd immunity, also called community immunity, happens when enough people are protected from a contagious disease. This makes it harder for the disease to spread. People may gain protection through vaccination or past illness, but vaccination is the safer choice.

Hooker is wrong that a vaccine must work perfectly for community immunity to be possible. The level of protection needed depends on how easily a disease spreads. Measles spreads so easily that about 93% of people must be immune. For chickenpox, the level is about 80%-85%.

Community immunity helps protect newborns and people with medical conditions who cannot be vaccinated. These people may also face a greater risk of serious illness. No vaccine protects every person, so lower disease spread also helps vaccinated people avoid breakthrough infections. A breakthrough infection happens when a vaccinated person still gets the disease.

Outbreaks can still happen in communities with high vaccination rates. This is more likely when unvaccinated people gather in the same places, such as schools or playgroups.

Vaccination has a long record of protecting people from serious diseases. When we vaccinate, we protect ourselves, our families, and people who cannot be vaccinated. In short: “I protect you, and you protect me.”

Also check out Voices for Vaccines’ Community Immunity Toolkit for more information regarding herd immunity.