makers are planning to tweak their shots to target that new variant. take a listen now what moderna is proposing to do to improve vaccine efficiency and efficacy. >> i think we're going to learn this more definitively over the next 7 to 10 days. we're doing the experiments needed to establish whether the reduction in binding that could be there, nevertheless allows us to be protected against this variant virus. >> dr. scott moscowvich is a national consultant for covid-19 testing and joins me from hawaii. good to see you, doctor, as we are here on the cusp of new, extended travel bans, testing here in the united states. that testing regime for all incoming travelers now. this tightening, negative test requirements, how much do you think these measures will actually help in stopping the spread of the variant? >> not all that much, paula.