http://www.newsweek.com/science-data-behind-covid-19-booster-shots-explained-1620715

Federal health officials have announced that vaccinated Americans will need COVID-19 booster shots less than a year after receiving their initial immunizations against the virus.

Originally, some officials had repeatedly said that booster shots would not be needed for the time being, but on Wednesday, the U.S. Department of Human and Health Services said it was prepared to begin offering booster shots to everyone beginning September 20.