The effectiveness of the coronavirus vaccine being developed in the UK by AstraZeneca and Oxford University could be as high as 90% and has no serious side effects, the company announced today.
AstraZeneca Covid19 vaccine
The Phase III clinical trials unexpectedly found that, when the vaccine was administered as a half dose, followed one month later by a full dose, its effectiveness rose significantly to 90%, from 70% after two full doses one month apart.
While scientists are not certain why the initial half dose appears to be more effective, one possible idea being floated is that it is due to the gradual introduction to the immune system.
No serious side effects have been noted, with minor side effects including mild nausea, headaches and sore arms.
“This vaccine’s efficacy and safety confirm that it will be highly effective against COVID-19 and will have an immediate impact on this public health emergency,” said Pascal Soriot, Astra’s CEO, in a statement.
While the overall effectiveness was lower than rival vaccines from Pfizer and Moderna, scientists noted that AstraZeneca's vaccine may come with advantages.
“Importantly, from what we have heard the vaccine seems to prevent infection, not just disease. This is important as the vaccine could reduce the spread of the virus as well as protect the vulnerable from severe disease,” said Peter Horby, a professor of emerging infectious diseases and global health at the University of Oxford.
The AstraZeneca vaccine, he added, “can be stored in the fridge, as opposed to the freezer like the other two vaccines, which means it is a more practical solution for use worldwide.”
The UK pharma company's Phase III trials mark another breakthrough in the worldwide fight against the Covid-19 pandemic, which has taken almost 1.4 million lives and devasted the global economy.
Shares in AstraZeneca fell by 1.1% in early morning trading, with traders perceiving the efficacy data as disappointing compared with results from rivals.
Efficacy fell to 62% when the vaccine was given as two full doses at least one month apart. The combined analysis from both dosing regimens resulted in an average efficacy of 70%.
The interim analysis was based on 131 infections among participants who received the vaccine and those in a control group who were given an established meningitis shot.
Despite efficacy data from AstraZeneca's viral vector vaccine being lower than that of US rivals' vaccines, the data will boost confidence about the development of a variety of vaccines using different approaches. Public health experts have said that a range of vaccines will be necessary to meet demand.
Last week, Moderna said its vaccine has been proved to be 94.5% effective.
A week earlier, Pfizer and BioNTech announced their vaccine had achieved 95% will full trial data released.
Russia’s Sputnik-V vaccine on November 11 was also shown to be more than 90% effective, though data was only based on 20 infections.
The Astra-Oxford vaccine uses a modified version of a chimpanzee common cold virus to deliver instructions to cells to fight the virus. This approach is a different one to that of the Pfizer-BioNTech and Moderna which deploys messenger RNA.
The company will now start preparation of the data to submit to the regulatory authorities.
It will also seek an emergency use listing from the World Health Organization to speed up availability in low-income countries.
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