In the Seychelles, Chile, Bahrain and Mongolia, 50 to 68 percent of the populations have been fully inoculated, outpacing the United States, according to Our World In Data, a data tracking project. All four ranked among the top 10 countries with the worst Covid outbreaks as recently as last week, according to data from The New York Times. And all four are mostly using shots made by two Chinese vaccine makers, Sinopharm and Sinovac Biotech. “If the vaccines are sufficiently good, we should not see this pattern,” said Jin Dongyan, a virologist at the University of Hong Kong. “The Chinese have a responsibility to remedy this.”... Disparities such as these could create a world in which three types of countries emerge from the pandemic — the wealthy nations that used their resources to secure Pfizer-BioNTech and Moderna shots, the poorer countries that are far away from immunizing a majority of citizens, and then those that are fully inoculated but only partially protected. China, as well as the more than 90 nations that have received the Chinese shots, may end up in the third group, contending with rolling lockdowns, testing and limits on day-to-day life for months or years to come. Economies could remain held back. And as more citizens question the efficacy of Chinese doses, convincing unvaccinated people to line up for shots may also become more difficult.