Russia’s coronavirus vaccine, Sputnik V, has shown 91.6% efficacy in late stage trials, The Lancet said on Tuesday.

The results from an interim analysis, which was published in The Lancet, also showed the vaccine provided full protection against moderate or severe cases of the coronavirus. The trial is ongoing and aims to enrol about 40,000 participants overall. So far around 20,000 participants, mostly white, have been involved in the trials.

Data from the cohort of people aged 60 and above showed that the vaccine was effective for the elderly.

No serious adverse events were found to be linked with the vaccination, reported The Guardian. Most of the reported adverse events were mild, including flu-like symptoms, pain at the injection site and weakness or low energy.

The trial does not include efficacy data of the vaccine for new variants of the coronavirus. However, Gamaleya Institute, Russia’s virology research centre that developed the vaccine, said that it expects Sputnik V to work against the new variants.

The vaccine is administered in two doses separated by 21 days. In the period after administering the the first shot, 16 cases of Covid-19 were found in the 14,964 people (0.1%) part of the vaccine group, while 62 infections were reported in the 4,902 individuals (1.3%) in the placebo group.

The analysis only includes symptomatic Covid-19 cases. The researchers have cautioned to conduct more tests to understand the effects of the vaccine on asymptomatic Covid-19 patients. Also, the durability of the protection offered by the vaccine remains to be seen as patients were followed for up to 48 days after their first dose.

Gamaleya Institute Director Alexander Gintsburg said the results were a “monumental achievement” and “a great success” in the fight against the pandemic.

“This recent positive phase 3 trial... is highly encouraging in terms of efficacy, a lack of serious side effects and seemingly equivalent protection in older patients,” said Dr Stephen Griffin, associate professor in the school of medicine at the University of Leeds.

The state-run Russian Direct Investment Fund, which sponsored research into the jab, said that Moscow is planning to produce up to 1.4 billion (140 crore) doses of the vaccine this year. “Russia has done everything right,” RDIF director Kirill Dmitriev said. “We were right to register it early, we were right to share with the world that we have one of the most efficient vaccines, and we were right to start vaccinating our at-risk personnel early. We saved lots of lives.”

Russia has so far reported 38,25,739 Covid-19 cases and 72,456 deaths, according to the John Hopkins University data.