Herd immunity is a form of indirect protection from infectious disease that can occur with some diseases when a sufficient percentage of a population has become immune to an infection, whether through previous infections or vaccination, thereby reducing the likelihood of infection for individuals who lack immunity.

What is herd immunity in terms of COVID-19?

Herd immunity occurs when a significant portion of a population becomes immune to an infectious disease, limiting further disease spread. For those who are not immune, they are indirectly protected because the ongoing disease spread is small.

Can you spread COVID-19 if you are vaccinated?

Vaccinated People Can Transmit the Coronavirus, but It's Still More Likely If You're Unvaccinated. COVID-19 vaccines continue to protect against severe illness but do not entirely block transmission. Fully vaccinated people are also less likely to contract the coronavirus than unvaccinated people.