After meetings with President Xi Jinping and Chinese ministers, Tedros Adhanom Ghebreyesus was impressed by their knowledge of the new flu-like virus and their efforts to contain the disease, which by then had killed scores in China and started to spread to other countries.

The advisers encouraged Tedros to use less effusive language out of concern about how he would be perceived externally, the person familiar with the discussions said, but the director general was adamant, in part because he wanted to ensure China’s cooperation in fighting the outbreak.

“We knew how it was going to look, and he can sometimes be a bit naive about that,” the person said. “But he’s also stubborn.”