MANILA (UPDATE) - President Rodrigo Duterte might be immunized with a Russian COVID-19 vaccine by May of next year at the earliest, Malacañang said Thursday as the Philippines gears up for its clinical trial beginning this year.

The 75-year-old Duterte, who volunteered to be among the first to be inoculated in public, might be immunized with the Russian vaccine by May 1, 2021, if the drug is proven safe and effective by March next year, Presidential Spokesperson Harry Roque said.

"Inaasahan natin na pupwedeng magpabakuna ang ating Presidente dito po sa Russian na bakuna sa Mayo 1, 2021," Roque said.

(We expect that the President can be immunized with the Russian vaccine by May 1, 2021.)

"It's not a metaphorical statement. He's willing to undergo it," he added.

Duterte, however, would need the approval of the Presidential Security Group before he gets the vaccine shot.

Presidential Security Group commander Col. Jesus Durante said Wednesday they would allow Duterte to be immunized as long as the vaccine gets approval from the Food and Drug Administration (FDA) and the Department of Health.

The Philippines and Russia are planning to run phase 3 clinical trials of Moscow's coronavirus vaccine from October this year to March next year, Roque said, noting that the drug might be registered with the local FDA by April next year.

Phase 3 clinical trials, according to the website of the FDA, involve "300 to 3,000 volunteers who have the disease or condition."

It is meant to test the efficacy and monitoring of adverse reactions of the drug.

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"Sa Abril, inaasahang marerehistro po ang bakuna ng Russia. At ibig sabihin po, sa Mayo 1, 2021 pa lamang na pupwedeng magpasaksak ng bakuna mula sa Russia ang ating Presidente," Roque said.

(We expect the Russian vaccine to be registered by April, which means that it is only by May 1, 2021 that our President can be inoculated with the drug.)

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Russian President Vladimir Putin declared his country as the first to approve a coronavirus vaccine on Tuesday even though final stage testing only started this week.

Russia's Sputnik V vaccine has been developed by the Gamaleya research institute in coordination with the country's defense ministry.

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Western scientists have previously raised concerns about the speed of development of Russian vaccines, suggesting that researchers might be cutting corners.

The World Health Organization's spokesman in Geneva Tarik Jasarevic said it was in "close contact" with Russian health authorities but that it was too soon for any WHO stamp of approval.

"Pre-qualification of any vaccine includes the rigorous review and assessment of all the required safety and efficacy data," he said.

In Berlin, a spokesman for the German health ministry told newspaper group RND that "there is no known data on the quality, efficacy and safety of the Russian vaccine," adding that "patient safety is of the highest priority."

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According to the Johns Hopkins University COVID-19 dashboard, more than 20.6 million coronavirus infections have been recorded across the world, with deaths nearing the 750,000-mark.

- with reports from Agence France-Presse