One in seven volunteers have complained of side effects including weakness and muscle pain after taking Russia’s highly touted coronavirus vaccine, Russia’s health minister said Tuesday.

Final clinical trials of the Sputnik V vaccine began in Moscow earlier this month amid questions over its long-term safety and effectiveness. 

Health Minister Mikhail Murashko said more than 300 out of the announced 40,000 volunteers have been vaccinated 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.

Murashko said the symptoms “level off” by the next day.

“The complications are described in the instructions and are predictable,” he said.

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

Russian government officials and party leaders have reported taking part in the trials.

Developers have in recent days begun distributing small batches of Sputnik V across Russian regions in parallel with the Phase 3 trials. The general population could get vaccinated in late November or early December, Murashko has said.

Russia has confirmed nearly 1.1 million cases of Covid-19 in the six months since its outbreak began, with a steady uptick in daily cases seen in recent days.

Public polling has said that nearly half of Russians do not plan to receive the coronavirus vaccine at any point.