Hate to "science" you but there seems to be confusion about herd immunity. This is from Johns Hopkins:
When most of a population is immune to an infectious disease, this provides indirect protection—or herd immunity—to those who are not immune to the disease.
For example, if 80% of a population is immune to a virus, four out of every five people who encounter someone with the disease won’t get sick (and won’t spread the disease any further). In this way, the spread of infectious diseases is kept under control. Depending how contagious an infection is, usually 70% to 90% of a population needs immunity to achieve herd immunity.
Measles, mumps, polio, and chickenpox are examples of infectious diseases that were once very common but are now rare in the U.S. because vaccines helped to establish herd immunity.
Other viruses (like the flu) mutate over time, so antibodies from a previous infection provide protection for only a short period of time. For the flu, this is less than a year. If SARS-CoV-2, the virus that causes COVID-19, is like other coronaviruses that currently infect humans,
we can expect that people who get infected will be immune for months to years, but probably not their entire lives. (Sidebar - "Effective vaccine" is also open to discussion. Typically the flu vaccine is only 40% to 60% effective in creating immunity. Will the COIVD vaccine be more effective?)
As with any other infection, there are two ways to achieve herd immunity: A large proportion of the population either gets infected or gets a protective vaccine. Based on early estimates of this virus’s infectiousness, we will likely need at least 70% of the population to be immune to have herd protection.
- In the best case, we maintain current levels of infection—or even reduce these levels—until a vaccine becomes available. This will take concerted effort on the part of the entire population, with some level of continued physical distancing for an extended period, likely a year or longer, before a highly effective vaccine can be developed, tested, and mass produced.
- The most likely case is where infection rates rise and fall over time; we may relax social distancing measures when numbers of infections fall, and then may need to re-implement these measures as numbers increase again. Prolonged effort will be required to prevent major outbreaks until a vaccine is developed.
Scientists are working furiously to develop an effective vaccine. In the meantime, as most of the population remains uninfected with SARS-CoV-2, some measures will be required to prevent explosive outbreaks like those we’ve seen in places like New York City.
The physical distancing measures needed may vary over time and will not always need to be as strict as our current shelter-in-place laws. But unless we want hundreds of millions of Americans to get infected with SARS-CoV-2 (what it would take to establish herd immunity in this country), life is not likely to be completely “normal” again until a vaccine can be developed and widely distributed.