in four states, alabama, louisiana, mississippi, and wyoming, less than half of adults have had at least one vaccination dose. the most at risk, communities with low vaccination rates with more than half of the u.s. population still not fully vaccinated, health experts worry about another surge fueled by the delta variant. we have parts of the united states where we don t have a lot of vaccination, and we also don t have a lot of prior infection. those are going to be the more vulnerable parts of this country. the world health organization urging vigilance. everyone should recognize this pandemic s not over. this is really not the time for us to encourage a lot of social mixing, to encourage mass events, especially without precautions. reporter: but across the nation a summer of normal activities back in full swing. the number of people traveling by air hit a new pandemic-era record sunday. the tsa says it screened 2.1 million people at airports, a number likely to be dwarfed t