gathering indoors with high-risk people. >> order the tests before you need them. if they wait until they have an issue, by the time the tests arrive, the optimal time for testing may well have passed. >> reporter: dr. william schaasc schaafer in authority on immunization practices. >> you will have to find testing resources elsewhere. >> reporter: casey, what's not clear is whether or not the postal service is adding more mail carriers to deliver these tests given the staffing issues they faced. two of the postal unions tell me their understanding is they will not be adding any mail carriers. it will fall on those already on staff. we haven't gotten much in the way of logistics from usps other than the postal service telling us they are confident they can get this done. kasie? >> gabe cohen, thank you very