banned air travel from the south african countries. do you think the u.s. should do that? . >> obviously as soon as we find out more information we will do it as quickly as we can. you dent want to say you are going to do it until you have scientific reason to do it. >> so if the u.s. starts to see -- yes, i know we are awaiting more information. we need to understand how this works. if the u.s. starts to see these cases of this particular strain, what immediate measures have to be taken? there is always what the uk has done, block travel from south africa and related countries.