Date Set for Third Booster for COVID-19

#BKP dis­cuss­es the press con­fer­ence where Biden released future dates for COVID-19 Boost­er Shots. The CDC and FDA have put eight months as the time­frame between the sec­ond and third vac­cine shots. Why is a third boost­er need­ed? What are the new tac­tics in get­ting Amer­i­cans vac­ci­nat­ed?