Health clinics in Moscow will begin offering booster vaccine shots against COVID-19 on Thursday, the city's mayor said, as Russian officials scramble to contain a surge in cases blamed on the highly infectious Delta variant.

The health ministry issued new regulations for the national inoculation programme on Wednesday, recommending clinics begin administering booster doses to people vaccinated six months ago or more, making Russia one of the first countries globally to begin re-vaccination.

The campaign, which the health ministry defined as "emergency" vaccination, is motivated by a recent sharp rise in coronavirus cases, coupled with the low rate of vaccination in the country.

Despite beginning its vaccination programme in January, Russia has inoculated just 16% of its population, or 23 million out of a population of some 144 million, amid a low demand for shots and widespread distrust.

The health ministry said it would be pursuing "emergency" vaccination and recommending booster doses for vaccinated people every six months until at least 60% of the adult population is vaccinated.

Authorities initially expected to reach this target by the autumn. However, given the sluggish demand, the Kremlin said on Tuesday that this target would not be met.

Moscow Mayor Sergei Sobyanin said revaccination was available with any of Russia's four registered vaccines, but that the flagship Sputnik V and the one-component Sputnik-Light would initially be used at eight clinics across the city.

Scientists behind the Sputnik V shot have previously said that protection generated by the shot lasts much longer than six months, maintained by memory cells that stand ready to rapidly generate antibodies when encountering the virus.

However, scientists have recommended booster doses to keep the number of protective antibodies in the body at a high level considering the rapid spread of the Delta variant.

"We need to keep an eye on the strain, keeping antibody levels high through more frequent re-vaccination," said Alexander Gintsburg, director of the Gamaleya Institute which developed the vaccine.

"This is because memory cells are late to get to work ... they start to build up the right level of antibodies around the third or fourth day," he was cited as saying by the Interfax news agency last week.