Russia's "Sputnik-V" COVID-19 vaccine produced an antibody response in all participants in early-stage trials, according to results published on Friday by The Lancet medical journal that were hailed by Moscow as an answer to its critics.
The results of the two trials, conducted in June-July this year and involving 76 participants, showed 100% of participants developing antibodies to the new coronavirus and no serious side effects, The Lancet said.
Russia licensed the two-shot jab for domestic use in August, the first country to do so and before any data had been published or a large-scale trial begun.
"The two 42-day trials – including 38 healthy adults each – did not find any serious adverse effects among participants, and confirmed that the vaccine candidates elicit an antibody response," The Lancet said.
"Large, long-term trials including a placebo comparison, and further monitoring are needed to establish the long-term safety and effectiveness of the vaccine for preventing COVID-19 infection," it said.
The vaccine is named Sputnik-V in homage to the world's first satellite, launched by the Soviet Union. Some Western experts have warned against its use until all internationally approved testing and regulatory steps have been taken.
But with the results now published for the first time in an international peer-reviewed journal, and with a 40,000-strong later-stage trial launched last week, a senior Russian official said Moscow had faced down its critics abroad.
"With this (publication) we answer all of the questions of the West that were diligently asked over the past three weeks, frankly with the clear goal of tarnishing the Russian vaccine," said Kirill Dmitriev, the head of the Russian Direct Investment Fund (RDIF), Russia's sovereign wealth fund, which has backed the vaccine.
On Friday, the World Health Organization's chief scientist said a coronavirus vaccine would be ready internationally by mid-2021.
"Certainly by the middle of 2021, we should start to see some vaccines flowing into countries so they can start immunizing their populations," Dr. Soumya Swaminathan said at a news briefing in Geneva.