Johnson & Johnson’s one-shot COVID-19 vaccine is more effective in the United States than in other parts of the world, the company said.

The vaccine was 72% effective in the U.S., but that percentage dropped in Latin America to 66% and in South Africa to 57%, 28 days post-vaccination, the company announced Friday. Overall, the vaccine was 66% effective in preventing moderate to severe COVID-19, 28 days after vaccination, Johnson & Johnson said.