In antibody tetors when you do the a third dose. that is tonight s last word. the 11th hour with brian williams starts now. good evening. racing to put out the firestorm ignited by the debacle from afghanistan. the president told abc news that the military mission to get americans out of country, taliban permitting, could extend past august 31st. all troops are supposed to be out by august 31st. even if americans and our allies are trying to get out. they ll leave? we re going to do everything we can to get all americans out and our allies out. does that mean troops will