“ As many as one in five Americans would refuse to take a coronavirus vaccine, according to a new poll that follows a surge of anti-vaccine content online“

https://www.forbes.com/sites/andrewsolender/2020/05/08/many-...

That’s a real life effect. Also from this article: “ Researchers at Johns Hopkins estimate that at least 70% of the population will have to be immune to provide herd protection against the novel coronavirus.“