As she fried fish to pay for her bills and rent, Caroline Onyango was struck by optimistic news reports broadcast in her home city of Nairobi, Kenya, this spring that noted the swift rollout of coronavirus vaccinations in the U.S. and other western countries. For the first time in a devastating year, Onyango grew hopeful that foreign tourists would return to East Africa, allowing her to go back to work as a senior tour guide for a safari company.