One in seven volunteers complained of side effects after being injected with Sputnik V, Russia’s experimental vaccine against the coronavirus disease (Covid-19), the country’s health minister has said.

Mikhail Murashko, the Russian health minister, said more than 300 out of the announced 40,000 volunteers have been vaccinated with Sputnik V so far, according to the state-run TASS news agency.

“Approximately 14% have small complaints of weakness, muscle pain for 24 hours and an occasional increase in body temperature,” TASS quoted Murashko as saying on Wednesday, according to Moscow Times.

The minister said the symptoms after being injected with the anti-coronavirus vaccine “level off” by the next day. “The complications are described in the instructions and are predictable,” he said, according to TASS.

Volunteers are expected to receive a second shot of the adenovirus-based viral vector vaccine within 21 days of the first.

The Sputnik V has yet to complete large scale clinical trials but was approved by the Russian government last month, becoming the first Covid-19 vaccine to be cleared for human use anywhere in the world.

Final clinical trials of the Sputnik V vaccine began in Moscow earlier this month.

Scientists have, however, cautioned against the use of any shot that has not passed full safety and efficacy checks.

The Russian health minister’s comments came after the country’s sovereign wealth fund said it has reached an agreement with pharmaceuticals major Dr Reddy’s Laboratories for clinical trials and distribution of Sputnik V in India, a process that is yet to be cleared by the Drugs Controller General of India (DCGI).

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Russian Direct Investment Fund (RDIF) has said it supply 100 million doses of the vaccine to Dr Reddy’s after regulatory approval in India. Indian officials said approvals will be given only after a thorough review.

Sputnik V did not lead to side effects and triggered an adequate immune response in 76 volunteers according to phase 1/2 trial data published in The Lancet journal earlier this month. But the results have been disputed by some scientists, who have sought a review of the data, citing what they said were striking similarities between patients.

RDIF reiterated on Wednesday that the vaccine is safe. “The Sputnik V vaccine, which is based on well-studied human adenoviral vector platform with proven safety, is undergoing clinical trials for the Coronavirus pandemic. Deliveries could potentially begin in late 2020 subject to completion of successful trials and registration of the vaccine by regulatory authorities in India,” a statement said.

The Sputnik V is among several vaccine candidates being considered by Indian authorities for the country. Dr Balram Bhargava, the director general of the Indian Council of Medical Research (ICMR), earlier said that a high-level government committee was looking into the data coming from Russia on its Covid-19 vaccine.