Vladimir Putin said he took part in a trial for a nasal COVID-19 vaccine.
He also received a booster shot of Russia's own Sputnik vaccine on Sunday.
Putin said his immunity had been waning since he got his first vaccine shots.
Russian President Vladimir Putin said he took an experimental nasal COVID-19 vaccine.
Putin said on Wednesday that he had taken part in tests for the nasal form of the vaccine, Russian news agency TASS reported.
He also received a booster shot of Russia's homegrown COVID-19 vaccine, named Sputnik Light, on Sunday.
In a Wednesday statement, Putin described being asked to breathe in, then being given the vaccine in powder form delivered by syringe.
Putin said he had been experiencing waning immunity due to the time that had passed since his earlier vaccines, TASS reported.
A Putin spokesperson had told reporters on Monday that Putin would take part in the nasal vaccine trial once doctors approved him to do so, TASS reported.
Putin was vaccinated with Russia's own coronavirus vaccine, Sputnik V, earlier this year.
Daily COVID-19 deaths in Russia reached a new high in November. Just under 42% of the country's population have been vaccinated, Reuters reported.