Officials in Brazil and Turkey have complained that Chinese companies have been slow to ship the doses and ingredients. Disclosures about the Chinese vaccines has been slow and spotty. The few announcements that have trickled out suggest that China’s vaccines, while considered effective, cannot stop the virus as well as those developed by Pfizer and Moderna, the American drugmakers.

In the Philippines, some lawmakers have criticized the government’s decision to purchase a vaccine made by a Chinese company called Sinovac. Officials in Malaysia and Singapore, which both ordered doses from Sinovac, have had to reassure their citizens that they would approve a vaccine only if it has been proven safe and effective.

“Right now, I would not take any Chinese vaccine because there’s insufficient data,” said Bilahari Kausikan, an influential former official at Singapore’s Ministry of Foreign Affairs. He added that he would consider it only with “a proper report.”