Candidate COVID-19 vaccine Sputnik V has shown an interim efficacy of 91% based on analysing results from around 18,000 volunteers, some of whom got the actual vaccine and some who got a placebo, the Russian Direct Investment Fund (RDIF) said in a press statement on Tuesday.
The vaccine candidate is also being tested on human volunteers in India and would cost “less than $10 [₹700] for international markets”, the RDIF said in a statement. The latest trial data doesn’t include the Indian volunteers.
While the interim vaccine efficacy numbers are in same range as trial data reported by biotechnology and pharma companies such as Pfizer-BioNTech (95%), Moderna (94.5%) and Oxford-AstraZeneca (with an efficacy of 70%), Sputnik V appears, so far, to have relatively lower protectivity.
For instance, according to the clinical trial protocol, there were three volunteers who got the vaccine for every one who got the placebo. Of the 14,095 who were inoculated with the actual Sputnik V vaccine, 8 later tested positive and of the smaller placebo group, of 4,699 nearly four times as many--31--tested positive. From this, is derived the efficacy rate of 91%. This also translates to 1:4 protectiveness odds.
By comparison, of the 95 cases Moderna analysed, 90 cases were observed in the placebo group versus 5 cases observed in the mRNA-1273 group—that is a 1:18 ratio.
Of the 170 cases of COVID-19, as specified in the Pfizer-BioNTech study protocol, 162 cases were observed in the placebo group versus 8 cases in those vaccinated—a 1:20 ratio. The Oxford-AstraZeneca vaccine, being tested by the Serum Institute of India, relied on 131 positives but a break up of placebo and vaccinated volunteers wasn’t available.
“Sputnik V relies on only 39 cases and that’s too low a number for an efficacy evaluation. That said this is an interim result—like the others—and we should wait for the full data. The positive side is that like the other vaccine candidates, this too is successfully attacking the spike protein and hence shows protection,” said Shahid Jameel, virologist and Head, Trivedi School of Biosciences, Ashoka University.
Also read: COVID-19 vaccine Sputnik V shows 92% efficacy, says Russia
Sputnik V has been developed by the Gamaleya National Research Center for Epidemiology and Microbiology and is being funded and promoted by the RDIF, Russia’s sovereign wealth fund.
The latest results, which are yet to be announced in a medical journal, were gleaned from ongoing double-blind, randomised, placebo-controlled Phase III clinical trials in Russia’s history involving 40,000 volunteers.
Of these, only 18,794 got both doses of the trial vaccine that are being administered 21 days apart. The analysis was done a week after the second dose was administered.
Also read: The Hindu Explains | What do we know about Russia’s COVID-19 vaccine candidate Sputnik V?
‘Efficacy’ rate
An ‘efficacy’ rate differs from vaccine ‘effectiveness’. The latter shows how protective a vaccine is when it is actually administered in the general population and efficacy--the number cited by pharmaceutical companies announcing trial results--only shows what fraction of those who got the vaccine tested positive versus compared to those who tested positive among those who got a placebo during the clinical trial phase. It is possible for a vaccine’s effectiveness to be much lower than its efficacy, according to Mr. Jameel, as the former depended on how effectively the vaccine was transported from a central facility to the furthest corners. “In practical terms, I’d be happy with a vaccine that’s 60% efffective, that’s accessible to all than one with 90% that’s only available to 20% of a population,” he stated.
Like Sputnik V these results are based on interim analyses from ongoing phase-3 trials.
The Russian vaccine used two different vectors based on the human adenovirus, which reportedly allows for a stronger and longer-term immune response as compared to vaccines using one and the same vector for two doses.
