Johnson & Johnson Vaccine a Key Player in Achieving Herd Immunity by Early Fall On 2/25/21 at 6:00 AM EST The Food and Drug Administration (FDA) could authorize the distribution of Johnson & Johnson's COVID-19 vaccine this week. With this new vaccine, combined with increased supplies and access to the shots, America's on track to return to a more normal life by early fall. Without the one-dose shot, America would need to significantly ramp up its vaccination efforts to reach herd immunity before next winter. Vaccines from Pfizer and Moderna require two shots, and at America's current rate of administering doses, it could take nearly a year to fully inoculate up to 85 percent of the population. The benefit of the Johnson & Johnson vaccine is that full vaccination is completed with one shot.