MOSCOW (AP) — Russian scientists say the country’s Sputnik V vaccine appears safe and effective against COVID-19, according to early results of an advanced study published in a British medical journal.

The news is a boost for the shot that is increasingly being purchased by nations around the world who are desperate to stop the devastation caused by the pandemic.

Researchers say based on their trial, which involved about 20,000 people in Russia last fall, the vaccine is about 91% effective and that the shot also appeared to prevent people from becoming severely ill with COVID-19. The study was published online Tuesday in the journal, Lancet.

Scientists not linked to the research acknowledged that the speed at which the Russian vaccine was made and rolled out was criticized as “unseemly haste, corner cutting and (with) an absence of transparency.”

“But the outcome reported here is clear,” British scientists Ian Jones and Polly Roy wrote in an accompanying commentary. “Another vaccine can now join the fight to reduce the incidence of COVID-19.”

You can read the full article published in the Lancet below:

The Sputnik V vaccine was approved by the Russian government with much fanfare on Aug. 11. President Vladimir Putin personally broke the news on national television and said that one of his daughters had already been vaccinated with it. At the time, the vaccine had only been tested in several dozens of people.

Some early results were published in September, but participants had only been followed for about 42 days and there was no comparison group.

The latest study is based on research involving about 20,000 people over age 18 at 25 hospitals in Moscow between September and November, of whom three-quarters got two doses of the Russian vaccine 21 days apart and the remainder got placebo shots.

The most commonly reported side effects were flu-like symptoms, pain at the injection site and fatigue. Serious side effects were rare in both groups and four deaths were reported in the study, although none were considered to be the result of the vaccine.

The study included more than 2,100 people over age 60 and the vaccine appeared to be about 92% effective in them. The research is ongoing but in December, Russia’s Health Ministry said it would cut the size of the study from the expected 40,000 to about 31,000 volunteers that have already enrolled. Developers of the vaccine cited ethical concerns about using placebo shots.

The Russian vaccine uses a modified version of the common cold-causing adenovirus to carry genes for the spike protein in the coronavirus as a way to prime the body to react if COVID-19 comes along. That’s a similar technology to the vaccine developed by AstraZeneca and Oxford University. But unlike that two-dose vaccine, the Russians used a slightly different adenovirus for the second booster shot.

Some experts say that approach may explain why the Russian vaccine seems to have produced a better immune response than the AstraZeneca vaccine, which has a reported efficacy rate of about 60 to 70%.

“This aims to drive higher immune responses to the target ‘spike’ by using two slightly different jabs,” said Alexander Edwards, an associate professor in biomedical technology at Britain’s University of Reading, who was not connected to the Russian research.

He said if you have two identical shots, it’s possible the immune system doesn’t get as big a boost from the second injection.

Sputnik V was rolled out in a large-scale vaccination campaign in Russia in December, with doctors and teachers the first in line. Last month, Putin ordered mass immunizations to start.

In early January, the Russian Direct Investment Fund that bankrolled the jab said that over 1 million Russians have already been vaccinated with the domestically developed shot. Some Russian media questioned the number and suggested that the rollout has been much slower, with many Russian regions reporting small numbers of vaccinations.

Outside Russia, Sputnik V has received authorization in over a dozen countries, according to the fund — including former Soviet republics of Belarus, Armenia and Turkmenistan; Latin American nations including Argentina, Bolivia and Venezuela; some African nations as well as Serbia, Iran, Palestine and UAE.

In the European Union, the shot has received initial authorization in Hungary and is still subject to final approval by the country’s National Public Health Center.

Hungary’s first shipment of Sputnik V — 40,000 doses — arrived on Tuesday, Foreign Minister Peter Szijjarto said on Facebook. Hungary expects to get enough Sputnik V vaccine to treat 1 million people in the next three months.

Batches of the vaccine have already been supplied to six countries. In all, more than 50 countries submitted applications for 2.4 billion doses, a RDIF spokesman told The Associated Press.

Algeria will begin producing the Sputnik V vaccine “within the coming weeks,” according to Kamel Mansouri, the head of Algeria’s national agency for pharmaceuticals.

The first batch of 50,000 doses of Sputnik V was flown to Algeria from Russia on Thursday, a tenth of what had been previously announced by the North African government. A cargo of 50,000 AstraZeneca doses arrived on Monday.

Mansouri said Algeria and Russia were in advanced discussions over Sputnik V and the vaccine would be manufactured at the government-owned SAIDAL facility.

“It is time that Algeria, a country that imports vaccine, be able to produce it on site to respond to the needs of the vaccination campaign, and to export in a second phase,” he said Tuesday on national television.