These American expats are willing to travel more than 5,000 miles for their shots

Americans living overseas seem to be heading back to the United States in growing numbers to get vaccinated -- especially those in Europe frustrated by a vaccine rollout that the World Health Organization slammed in a recent report as "unacceptably slow."

(CNN) — Eric Barry has been riding a seemingly never-ending wave of uncertainty in his life over the past year. The 35-year-old writer and podcast host, who is originally from California's Bay Area, was researching a novel in Ecuador when the global pandemic erupted in March 2020. Over the next 12 months, as Barry tried to establish his new home base in Berlin, where he's studying for a master's degree, he faced challenge after challenge: an apartment that fell through in Berlin's notoriously difficult rental market; trying to track down a German residence permit likely mailed to his former address; and navigating an unfamiliar healthcare system in which he has no idea when he'll be vaccinated.