Herd immunity possible as vaccination access expands "Herd immunity" is something getting a lot of attention. Health experts are looking at the likelihood of reaching it and what it means as we look to get back to normal. and last updated 2021-05-12 21:46:07-04 COLORADO â More than 2.2 million Coloradans are fully vaccinated, but the likelihood of reaching herd immunity with COVID-19 is something that's still months away, if at all. Public health leaders say the key is getting about 70 percent of the state's population fully vaccinated, or recently recovered from COVID-19. Right now ar...