< BACK NEXT > 3 of 8 - Herd immunity
The single infected person is now introduced to a population that is highly vaccinated. As is common in SIR models, this is done by giving them a shortcut into the recovered fraction of the population.

When you play the scenario you'll see that very few (sometimes none) of the susceptibles are infected because they have indirect protection from those who are vaccinated.

This phenomenon is called herd immunity.

The scenario automatically stops when there are no infections.

Replay the scenario a few times (Reset then Play) to see different random starting conditions.

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