Sinovac Biotech Ltd.’s vaccine is wiping out COVID-19 among health workers in Indonesia, an encouraging sign for the dozens of developing countries reliant on the controversial Chinese shot, which performed far worse than Western vaccines in clinical trials.

Indonesia tracked 25,374 health workers in Jakarta for 28 days after they received their second dose and found that the vaccine protected 100% of them from death and 96% from hospitalization as soon as seven days after, Health Minister Budi Gunadi Sadikin said in an interview Tuesday. The workers were tracked until late February.

Sadikin also said that 94% of the workers had been protected against infection — an extraordinary result that goes beyond what was measured in the shot’s numerous clinical trials — though it’s unclear if the workers were uniformly screened to detect asymptomatic carriers.