> There's no such thing as natural herd immunity. I disagree. I just think the humans most severely vulnerable to the flu died off during the first few waves.

> There's no such thing as natural herd immunity. I disagree. I just think the humans most severely vulnerable to the flu died off during the first few waves. Consider small pox. It was a novel virus for the Native Americans, who had no "natural herd immunity" and they got eviscerated by small pox. Colonists, despite not having vaccines, and despite still being able to get small pox, were not eviscerated since the virus wasn't able to spread and/or kill as well due to their natural immune systems. What do you call this if not "natural herd immunity"? If you kill off all the weak and vulnerable, leaving only survivors and survivors' offspring who are virus-resistant... then you now have "natural herd immunity".