(Adds details, background)
By Polina Ivanova
MOSCOW, Feb 20 (Reuters) - Russia on Saturday approved athird coronavirus vaccine for domestic use, Prime MinisterMikhail Mishustin said on state TV, though large-scale clinicaltrials of the shot, labelled CoviVac and produced by theChumakov Centre, have yet to begin.
Russia has already approved two COVID-19 vaccines, includingthe Sputnik V shot, developed by Moscow's Gamaleya Institute,following a similar approach of granting approval before seeingany late-stage trial results.
The preemptive approvals had raised concerns among somescientists in the West, but inoculations with those first twoshots began on a mass scale in Russia only after trials wereconcluded and showed success.
Sputnik V was approved in August and late-stage trials beganin September. Mass vaccination was launched in December, afterpreliminary trial results showed the vaccine to be 91.4%effective.
Since then, more than two million Russians have beenvaccinated with at least the first dose of Sputnik V, HealthMinister Mikhail Murashko said on Feb. 10.
Rollout of a second vaccine, developed by the VectorInstitute in Novosibirsk, is beginning.
"Today, Russia is the only country to have already threevaccines against COVID-19," Prime Minister Mishustin said.
The Chumakov Centre, founded in 1955 in St Petersburg byMikhail Chumakov, is known for its work with U.S. scientistAlbert Sabin at the height of the Cold War, which led to theproduction of the widely-used polio vaccine.
DIFFERENT TYPE OF VACCINE
Unlike the Sputnik V vaccine, which uses a modified harmlesscold virus that tricks the body into producing antigens to helpthe immune system prepare for a coronavirus infection, theCoviVac vaccine is a "whole-virion" vaccine.
This means it is made of a coronavirus that has beeninactivated, or stripped of its ability to replicate.
"The vaccine we have developed... reflects the whole historyof Russian, as well as global, vaccine science," the ChumakovCentre's director, Aidar Ishmukhametov, said on Saturday.
The advantage, according to virologist Alexander Chepurnov,cited by outlet Lenta.Ru, is that CoviVac includes all elementsof the virus, creating a broader immune response that is likelyto protect against any variants.
However, testing Russia's COVID-19 shots against SARS-CoV-2variants that have emerged in the UK, South Africa and elsewhereis in its early stages. President Vladimir Putin on Mondayordered a review of Russia's COVID-19 vaccines to be presentedby March 15 assessing their ability to protect against the newvariants.
RESULTS SO FAR
Globally, one other major vaccine candidate - India'sCOVAXIN by Bharat Biotech - uses the "whole-virion" approach.
India's drug regulator has touted the shot's ability to actagainst the whole body of a virus instead of just its"spike-protein" tip, potentially making it more effective incase of mutations.
The CoviVac shot is given in two doses, 14 days apart. It istransported and stored at normal fridge temperatures, of 2 to 8degrees Celsius (35.6 to 46.4 Fahrenheit), Deputy Prime MinisterTatiana Golikova said in a government briefing in January.
The shot has already been tested for safety on 200 peopleaged between 18 and 60, Ishmukhametov told the state-runVesti-24 news channel in late January.
This early-stage trial began on Sept. 21 last year,according to the state clinical trials register. It showed noside-effects, including no rise in temperature, Ishmukhametovsaid.
Mid-stage trials to test volunteers' immune responses wereongoing, he said at the time.
Only a placebo-controlled, large-scale trial could ascertaineffectiveness, he added. This is due to begin now that thego-ahead has been granted.
The first 120,000 doses, however, will be produced andreleased to the national inoculation programme in March,Mishustin said.
Then, the Chumakov Centre will produce around half a milliondoses per month on its platforms, Ishmukhametov said onSaturday.
Deputy Prime Minister Golikova also announced on Saturdaythat Russia will produce 88 million vaccine doses in the firsthalf of this year, including 83 million Sputnik Vdoses.(Reporting by Polina Ivanova; Additional reporting by DaryaKorsunskaya and Gleb Stolyarov;Editing by Nick Macfie, Kate Kelland and Frances Kerry)