Moscow (CNN)Russian President Vladimir Putin has tested an experimental Covid-19 nasal vaccine that is not yet in clinical trial phase, his fourth vaccination in total, he said Wednesday.

Putin also received a Russian-made Sputnik Light booster on Sunday, six months after his second dose of Sputnik V.

After receiving the booster shot, Putin volunteered to take part in testing the intranasal vaccine in development by the Gamaleya Center, the maker of Sputnik V and the subsequent single dose Sputnik Light, he said at a televised meeting with government members.

Putin said he "didn't feel anything" after the intranasal vaccination. "Today, after these two procedures -- the injection and the nasal form, the second part -- I already went in for sports this morning. So I can testify that everything is developing the way our scientists say it does," he told ministers.

In mid-October, the Russian Ministry of Health approved clinical trials of a nasal spray form of the Sputnik V vaccine developed by the Gamaleya Center, according to RIA Novosti.

Gamaleya is still testing the efficacy of the nasal vaccine, according to the deputy director of Gamaleya, Denis Logunov. "I must confess it is an off-label administration basically, as usual, we are testing it on our employees," Logunov told Putin in a televised conversation after administering the booster on Sunday. Putin responded by asking Logunov whether he could "take part in this experiment."

Logunov said the intranasal form was developed in order to "induce barrier immunity," which with Covid-19, "refers to our immune organs located in the nose and the pharynx."

"We also know that vaccines administered through parenteral method, or intramuscular injection, are effective, but they have limited ability to induce immunity from so-called breakthrough infection and symptomatic illness. We need to deliver the agent through the mucous membranes to induce barrier immunity."

According to Logunov, the nasal vaccine "just needs a little finalizing then it will go into clinical tests, and after that, we certainly plan to begin the new vaccine rollout." It is "convenient, painless, with an absolute minimum of side effects," he said.

Russia has lagged behind much of the world when it comes to getting its population inoculated, despite being the first country in the world to approve a coronavirus vaccine, Sputnik V, for use in August 2020.

According to the latest numbers available from October, 47.8 million Russians have received their first shot and 42.4 million have been fully vaccinated in a country with a population about 146 million.

Russia has struggled to bring rising coronavirus infections under control in recent weeks.

The country has recorded 262,733 deaths from Covid-19, according to the latest figures from Johns Hopkins University.

CNN's Anna Chernova reported from Moscow and Lindsay Isaac from London.

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