The big news here is the publication of the Gamaleya Institute’s “Sputnik-V” vaccine data. In the end, we have data on about 15,000 patients who were vaccinated, and on about 5,000 in the placebo control group. Volunteers got a dose of an adenovirus-26 vector vaccine, followed 21 days later by a dose of the identical construct in an adenovirus-5 vector. This is to try to avoid the immune response to the vector itself, which has always been a concern with any of the viral-vector vaccines (against the coronavirus and against anything else!) Another concern is the possibility that once you’ve had such an adenovirus-vector treatment, that you might be in trouble for further vaccinations that use the same vector (and this remains an open question).
Counting from the day of the second dose, there were 16 cases of disease in the vaccinated cohort, and 62 cases in the controls. That comes out to a two-dose vaccine efficacy of 91.6%, with a 95% confidence interval of 85.6% to 95.2%. In no subgroup (age, gender, etc.) was it lower than 87%. Importantly, and in line with the other vaccine trial data we’ve seen so far, there were no cases at all of moderate or severe disease in the vaccinated group after the date of the second dose. Figure 2 of the paper shows that the effect of the first shot kicks in around day 16-18 – a bit longer than what’s been seen with the mRNA vaccines, but the curve afterwards shows the same strong protection. Safety looks good, with few adverse events and nothing serious connected with the vaccine itself.
So these data look strong, strong enough that a single-dose trial is underway as well (and that will make an interesting comparison with J&J’s Ad26-vector vaccine, for which we have single-dose data with a two-dose trial underway). We’ll be getting more real-world data on this one, as it’s being deployed in several countries, and it will certainly be worth seeing how it handles the variant strains that we’re seeing now. My expectation is that it will deal with the B.1.1.7 one at nearly the same efficacy and drop down to the 50-60% efficacy range against the B.1.351 strain, as has been seen with the other vaccines where we have such data. Based on the numbers we have, I see no reason why this vaccine can’t make a solid contribution to fighting the pandemic, and I’m very glad to have another efficacious one out there for use.
For updates on the Oxford/AstraZeneca vaccine, I’ll refer everyone to this post, and likewise for updates on the J&J vaccine, this recent post. As for the CanSino Ad5 vaccine, there are reports in Chinese media of positive safety and efficacy data, which means that it’s officially moving into Phase III. That sounds a bit odd, considering that it’s apparently being offered in Pakistan, Malaysia, and other countries already, but these are odd times. There is also word of a combination trial with this one and the Sputnik vaccine as well, which would replace the second (Ad5) dose of the former with the CanSino one.
Of the other viral vectors I reported on in the most recent post, the big news has been on the Vaxart oral candidate. Unfortunately, the company reported that they were unable to detect serum neutralizing antibodies in most trial subjects, which has to be considered an unwelcome development. Their press release sounds a lot more positive than that (as is so often the case), but it’s rather light on actual data. It may be (although it seems less likely) that the real-world efficacy of this candidate will depend on its mucosal immunogenicity and that the lack of neutralizing antibodies in serum is a red herring, but the only way to convince people of that will be with lots of strong efficacy data in human trials.
