[Herd immunity] contains the following assumptions:
- Vaccine really are effective in protecting you against disease;
- Once you get a vaccine, you are protected for a long time, or for life, against that disease;
- Vaccines protect you from getting infected and transmitting the disease;
- Herd immunity can be acquired through vaccination just as it can be acquired naturally (i.e. when a significant number of people in a community contract and overcome a disease, and then have natural antibodies against it).
— Makia Freeman, The Freedom Articles