MOSCOW — Russia on Tuesday became the first country to officially register a coronavirus vaccine and declare it ready for use, despite international skepticism. President Vladimir Putin said that one of his daughters has already been inoculated.

Putin emphasized that the vaccine underwent the necessary tests and has proven efficient, offering a lasting immunity from the coronavirus. However, scientists at home and abroad have been sounding the alarm that the rush to start using the vaccine before Phase 3 trials — which normally last for months and involve thousands of people — could backfire.

Speaking at a government meeting Tuesday, Putin emphasized that the vaccine has undergone proper testing and proven safe to use.

“I would like to repeat that it has passed all the necessary tests,” he said. “The most important thing is to ensure full safety of using the vaccine and its efficiency.”

The Russian leader added that one of his two daughters has received two shots of the vaccine and is feeling well. “She has taken part in the experiment,” Putin said.

Putin said that his daughter had a temperature of 100.4° Fahrenheit on the day of the first vaccine injection, and then it dropped to just over 98.6° Fahrenheit the next day. It spiked again after the second shot, but went down again afterwards.

“She's feeling well and has high number of antibodies,” Putin added, not identifying which of his daughters received the vaccine.

Russian authorities have said that medical workers, teachers and other risk groups will be the first to be inoculated.

Putin emphasized that the vaccination will be voluntary.

Russian officials have said that large-scale production of the vaccine will start in September, and mass vaccination may begin as early as October.

The Associated Press contributed to this report.