Russian President Vladimir Putin said Wednesday that he has directed officials to begin large-scale vaccination against COVID-19 as early as next week, according to state media.

Why it matters: Russia, which has the fourth-largest coronavirus caseload in the world with more than 2.3 million infections, would be the first country to begin mass vaccination. Experts have criticized the lack of scientific transparency around the vaccine and the haste with which the Kremlin approved it.

• Putin said doctors and teachers will be first in line for the inoculation, and that Russia has produced about 2 million doses of its vaccine.
• The news came the same day that the U.K. became the first country in the world to clear Pfizer and BioNTech's vaccine for mass distribution.

The big picture: Russia earlier this month announced that its Sputnik V vaccine is 92% effective, a day after Pfizer announced its trials showed 90% efficacy. Several countries, including Brazil, In­dia, Mex­ico and Egypt, have already lined up to buy the vaccine, despite the lack of clarity about whether it is safe or effective.

Go deeper:As countries line up for Russia's vaccine, not everyone is buying it