It’s reported that Oxford-AstraZeneca is to combine its coronavirus (Covid-19) vaccine with the Sputnik V vaccine, developed by Moscow-based Gamaleya Research Institute of Epidemiology and Microbiology.
But not everything is going to plan.
The Russian connection
The Gamaleya vaccine, known as Sputnik V, claims 95% efficacy. Efficacy is defined as “how well a vaccine performs under the most ideal conditions”. These include “randomized controlled trials (RCTs), which are considered the gold standard of clinical trials“.
Russian Investment Fund CEO Kirill Dmitriev described the partnership between Gamaleya and Oxford-AstraZeneca as “an important step toward uniting efforts in the fight against the pandemic”.
England’s chief scientific adviser Patrick Vallance further explained regarding this team-up:
What it means is that you give one vaccine to get the immune system triggered up and another one to then boost it further with a different vaccine
This is what’s known as heterologous boosting.
Gamaleya is yet to publish a detailed study of its trials in a peer-reviewed scientific journal. Also, it’s reported that the Gamaleya vaccine approval was merely a conditional registration certificate that would depend on positive results following Phase 3 trials.
As for the Oxford-AstraZeneca vaccine trials, results provide different efficacy figures to the Gamaleya trials. Namely 62% when two full doses are administered, and 90% when a half dose is later followed by a full one.
The Guardian explained:
Those given the half dose and then full dose four weeks later were in a smaller group of 3,000 people, of whom 90% were protected against Covid. In the larger group, given two full doses, four weeks apart, efficacy was 62%.
a sub-set of volunteers had been mistakenly given a lower dose of vaccine due to problems manufacturing it. Bizarrely, that lower dosage produced a higher vaccine efficacy: around 90%. The scientists had no explanation for this anomaly.
Dr Simon Clarke, associate professor in cellular microbiology at University of Reading, commented on how the dosage that resulted in 90% efficacy did not include participants over age 55:
Data are most compelling for the cohort who got half a dose of the vaccine in their first jab.
Unfortunately, this cohort was relatively small, reducing the reliability of the findings – moreover it did not contain any older participants [age 55 or over].
Significantly, he pointed out:
it remains possible that if the regulators allowed the vaccine to be used in this manner, the most at risk group may not be protected.
The authors of the Oxford-AstraZeneca trials study acknowledge problems in the trials methodology – in particular that:
Vaccine efficacy in older age groups could not be assessed but will be determined, if sufficient data are available, in a future analysis after more cases have accrued.
Indeed, in a critical appraisal of the Oxford-AstraZeneca study that was also published in the Lancet on the same day, the authors point out:
The limitations [of the trials] include that less than 4% of participants were older than 70 years of age, no participants older than 55 years of age received the mixed-dose regimen, and those with comorbidities were a minority, with results for that subgroup not yet available.
The authors of the Oxford-AstraZeneca trials study conclude:
In future analyses with additional data included as they accrue, we will investigate differences in key subgroups such as older cohorts, ethnicity, dose regimen, and timing of booster vaccines.
Janssen (Johnson & Johnson) is meanwhile working on a single dose vaccine but is yet to commence phase 3 trials.
Here’s a complete list of coronavirus vaccines, most of which are still under trial.
Back in November, Boris Johnson announced with great gusto the news about the Oxford-AstraZeneca vaccine:
Incredibly exciting news the Oxford vaccine has proved so effective in trials. There are still further safety checks ahead, but these are fantastic results. Well done to our brilliant scientists at UniofOxford & AstraZeneca, and all who volunteered in the trials.
All quite premature, given the problems the trials have thrown up. But trying to make political capital out of the pandemic or hiding the true coronavirus death rates appears typical of Johnson and his ministers.
Meanwhile, it remains to be seen if combining the Gamaleya and the Oxford-AstraGenetica vaccines will prove better than two doses of the latter.
Featured image via Pexels
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