Locales that are more densely populated, including those with heavy use of mass transit, are likelier to see higher rates of person-to-person transmission. … And places where a lot of households include multigenerational members can also have a higher degree of spread, said Andrew Noymer, an associate professor of population health and disease prevention at the University of California-Irvine. … “As the herd immunity threshold is approached, potentially the rate of transmission slows,” Noymer said.
How helpful can herd immunity be in ending the coronavirus pandemic?
PolitiFact, June 3, 2020
June 3, 2020