The Oxford/AstraZeneca Covid-19 vaccine is safe and effective, according to a peer-reviewed study in The Lancet. Confirming the results published a few weeks ago, the vaccine has an overall efficacy of 70.4 percent, based on a pooled analysis of two different two-dose regimens: standard/standard and low/standard.
During the Phase 3 trial, 11,636 volunteers across the United Kingdom and Brazil received the jab. The data shows that the vaccine protects completely against severe cases from three weeks after the first dose.
“Today, we have published the interim analysis of the phase III trial and show that this new vaccine has a good safety record and efficacy against the coronavirus. We are hugely grateful to our trial volunteers for working with us over the past 8 months to bring us to this milestone,” Professor Andrew Pollard, director of the Oxford Vaccine Group and chief investigator of the Oxford Vaccine Trial, said in a statement.
The overall analysis looks good. However, there are some questions that require further investigation, which are currently being looked at. Due to a dose mishap that involved 1,367 people in the UK, they received half a dose first and then a full dose a month later. This mistake actually turned out to be a winning combination, providing 90 percent efficacy compared to 62 percent on two standard doses.
The half-plus-one is likely to be the approach that is eventually delivered, but since it was a much smaller pool of participants, we can’t consider the 90 percent value to be exact at this stage. Another aspect is age. Phase 2 data showed that the vaccine was well-tolerated and effective in older adults too, but the vast majority of participants in the Phase 3 trial are younger, making an assessment of the vaccine efficacy in people 56 or older less certain at this point in time
The vaccine is based on a genetically modified chimpanzee adenovirus. The virus can’t infect humans but “looks” like SARS-CoV-2, the virus behind Covid-19. The vaccine trains our immune system to respond to it and possibly (but this is still too early) even deal with the virus in asymptomatic cases.
“We have known for many years that adenoviral vectored vaccines fulfil the requirements for use against outbreak or pandemic diseases. They are safe, highly immunogenic, can be manufactured in large quantities at low cost and do not require frozen storage,” Sarah Gilbert, professor of Vaccinology at the University of Oxford, explained.
“Following the demonstration of vaccine efficacy in many preclinical studies, we now have clear evidence of efficacy in the trial results presented in a peer-reviewed publication today. Now under regulatory review, we hope that this vaccine will shortly be in use to start saving lives.”
The vaccine is cheaper than the Pfizer/BioNTech and the Moderna ones as well as easier to distribute and store. It is very likely that all these vaccines and more will play a part in stopping the pandemic. The team has now submitted the trial data to regulatory bodies.
