“Is there reliable data on effectiveness for the Russian vaccines?”

— Christopher in California

Russia surprised the world in August 2020 when it became the first country to register a coronavirus vaccine. Peer-reviewed data indicates the shots, which are used in several dozen countries, work well in preventing severe illness. But questions linger about the quality of the research, and the vaccine has yet to receive authorization from the World Health Organization.

Known as Sputnik V, Russia’s vaccine initially alarmed the international community because Russian officials authorized it before the results of Phase I and II clinical trials were published. Phase III trials, the gold standard for drug testing, hadn’t even begun when the shots started going into arms. Officials also used the Sputnik V Twitter account to cast doubt on Western vaccines. This didn’t inspire much confidence from scientists and health leaders. Many Russians were skeptical, too.

A turning point came in February, when the results of a large clinical trial were published in the Lancet, a well-respected medical journal. The study, which involved nearly 20,000 participants, showed that Sputnik V was about 91.6 percent effective at preventing symptomatic illness. That appeared to put in on par with the Pfizer-BioNTech and Moderna vaccines.

“The development of the Sputnik V vaccine has been criticized for unseemly haste, corner cutting, and an absence of transparency,” two independent scientists from the London School of Hygiene and Tropical Medicine wrote in a commentary in the Lancet. “But the outcome reported here is clear and the scientific principle of vaccination is demonstrated, which means another vaccine can now join the fight to reduce the incidence of COVID-19.”

Encouraging findings, to be sure. But researchers have since voiced hesitations about the study design, and Sputnik V’s developers have faced criticism for not sharing the underlying data from the clinical trials. In September, a group of scientists flagged what it said were “questionable” and potentially duplicative values in the trial data, and called on the study authors to provide a more detailed breakdown.

The WHO and European regulators say they, too, haven’t gotten all the data they’ve requested on Sputnik V. Reuters reported last month that the European Medicines Agency probably wouldn’t decide on whether to authorize the vaccine until at least the first quarter of 2022. Authorization from the WHO could also take months or even longer. A green light from the WHO is particularly important — without it, many Russians and others around the world who got Sputnik V won’t be able to travel to the United States, and the vaccine won’t qualify for the WHO’s Covax initiative to send doses to lower-income countries.

“Unfortunately, Sputnik V’s defenders have yet to acknowledge that there might be any actual safety or efficacy issues with the drug, let alone provide data to satisfy the regulators that have flagged concerns. This stance undermines public faith in the vaccine at home and abroad,” Paul Stronski, a Russia expert at the nonpartisan Carnegie Endowment for International Peace, wrote last week.

“Sputnik V clearly provides some protection against severe disease,” Stronski wrote, “but independently verified data remain hard to come by.”

— Derek Hawkins