Nature writes that many of the scientists' concerns about Sputnik V were eliminated at the publication stage of phase III trials. "The results showed that the vaccine is 91.6% effective in preventing COVID-19 and 100% effective in preventing severe infection."
The publication notes that Sputnik V is similar to AstraZeneca and Johnson & Johnson but the Russian vaccine uses different adenoviruses, which makes it more effective.
In 70 countries where Sputnik V is used, no serious side effects have been recorded, for example, death from thrombosis.