Yesterday, the people behind Russia’s main vaccine called Sputnik V released a preliminary analysis of its function. The news was pretty good: While the trial is underway and final results will have to wait, interim data suggests the vaccine could be more than 90 percent effective.
Sputnik V is based on similar technology to the vaccines being developed by Johnson & Johnson and the collaboration between Oxford and AstraZeneca. It is striking, however, that the preliminary efficiency is a lot higher than those vaccines show, and it is not clear how the Sputnik-specific characteristics could explain the difference.
The results come from a Phase III clinical trial with approximately 21,000 participants being conducted in Moscow. The participants were all over 18 years old, had not received any other vaccinations recently, were not pregnant or drug users, and met a number of other criteria. At enrollment, PCR-based SARS-CoV-2 testing was performed and participants were also tested for the presence of antibodies to the virus.
While data collection was integrated with the Russian health system — allowing researchers to obtain data from every participant receiving health care in the Moscow region — the trial itself was conducted by a commercial third party in the Netherlands.
The participants were so divided that three times as many people received the vaccine instead of a placebo. This assignment was random, and everyone involved was kept in the dark about who got what. Although the full trial will take several more months, the researchers took advantage of the fact that the vaccine requires two doses separated by 21 days to make an interim analysis of how effective the first dose was. So researchers repeated the PCR and antibody tests and checked their efficacy after a single dose.
The results were remarkably good. There were 16 cases among those who received the vaccine, compared with 62 cases among those who received a placebo. But consider that there were three times as many people in the vaccine group, which makes the effectiveness even higher; the researchers calculated it to be just over 90 percent. None of the people who received the vaccine had cases that reached the researchers’ definition of moderate or severe, while 20 people in the placebo group did. This suggests that the vaccine also lowers the risk of serious illness (something that has been seen with other vaccines).
After 21 days, almost all people who received the vaccine had antibodies to SARS-CoV-2, as you would expect. Only 15 percent of those in the placebo group also had antibodies to the virus, suggesting that they had had asymptomatic cases in the meantime. Based on the protocol of the trial, these were not counted as COVID-19 cases for the statistics.
A number of people were already determined to have SARS-CoV-2 before the 21-day time point, and were not included in the analysis that suggested 90 percent efficacy. That’s because these infections may have started before the vaccine had a chance to generate a significant immune response. However, when these are taken into account, the effectiveness of the vaccine drops slightly, to 73 percent.
Complications, medical and otherwise
There was one death in the vaccine and placebo groups due to random events in the first 21 days of the study. And two people who had been vaccinated developed severe COVID-19 within a week of being vaccinated and eventually died. Because of the timing of the onset of symptoms there, the researchers estimated that the deceased were likely already infected when they were vaccinated, but the virus hadn’t built up to levels detectable by PCR.
Side effects were typical of those caused by effective vaccines: fever, muscle aches and fatigue were common. However, when more serious adverse events were considered, they occurred more frequently in the placebo group (0.4 percent) than in vaccine recipients (0.3 percent).
So overall this looks great. In fact, it looks strangely great.
As mentioned above, the Sputnik V vaccine uses the same technology that has been tried by other companies: It places a key coronavirus protein in a harmless cold virus called adenovirus. The unique thing about Sputnik V is that it used two doses, with different strains of adenovirus in each dose. This limits the chance that the immune response will target the adenovirus itself, rather than the coronavirus protein it carries.
But that benefit wouldn’t come into play with a single dose, meaning we can expect similar effectiveness to that of the other two adenovirus-based vaccines. Given that the immune response is likely still increasing after 21 days, we would likely expect reduced effectiveness from any vaccine using the study protocol conducted here. Still seems to be Sputnik V significantly more effective than the offer from Johnson & Johnson or AstraZeneca.
Was data tampered with?
That in itself would be unexpected. But the results come in after a somewhat bizarre history for Sputnik V. Concerns include suggestions of manipulated data in the paper describing Phase I trials of the vaccine, along with Russia beginning widespread use of the vaccine ahead of clinical trials. research data. Russia also approved a second untested vaccine for good measure. So there are certainly quite a few reasons to be skeptical about Russia’s vaccine approach at this point.
Still, given the reasonable successes generated by other adenovirus-based vaccines, don’t be surprised if Sputnik V works. And there is still the prospect that using two different virus strains will make the vaccine more effective than others based on this technology. But we’ll have to wait for the full research data to know if that’s the case, along with some clear-cut answers about the strange history of these studies.
The Lancet, 2021. DOI: 10.116/S0140-6736(21)00234-8 (About DOIs).