Epistemix, a company developing epidemiologic models to simulate the transmission of disease has concluded that raising population immunity from approximately 50 to 70 percent would reduce incident (new) cases in every state by an average of 78 percent.  Greater benefits will accrue in states with dense populations including New York and Florida. The Epistemix model takes into account population density, waning of immunity and vaccination rates.

John Cordier, CEO of Epistemix stated, "now is a vital time to reach immunity thresholds that will allow life to safety return to normal in many states".  Studies demonstrated that if North Carolina was able to reach 70 percent immunity in a specific time the total number of COVID infections would decrease by 97 percent. In contrast at a level of 50 percent immunity the state will average over 300 cases per week compared to 10 cases with a population with the higher level of protection.

The White House established a goal of 70 percent of the U.S. population to receive at least one vaccination by July 4th.  This goal will probably not be met until late July given the disproportionate response to the availability of vaccines in states with a high proportion of rural residents.  Protection of the entire nation will depend on achieving high levels of immunity through vaccination.  This is especially necessary given the emergence of a number of variants including the Delta strain that now predominates in the UK and is responsible for 20 percent of cases currently diagnosed in the U.S.  The Lambda variant has emerged in Peru and is spreading rapidly in Latin America and will inevitably be introduced into the U.S.  Studies conducted in Europe have demonstrated that the three vaccines receiving U.S. Emergency Use Authorization are effective against the Alpha and Delta strains of SARS-CoV-2 preventing clinical manifestations and spread of SARS-CoV-2 responsible for COVID.