OE$\mathrm{.}6.$ Imapine that a new deadfy coresuvirus arlses and starta giobal pandemic. Experts ar$"$ morried because the disease spreads asalf, having a basic reprotuctive number, $R_1,$ of $8$ ; The good hews is that an effective vacent is quiekty developed. What minimum proportion of the Round your answer to two decimal places.