AstraZeneca, the firm developing the ChAdOx1 nCoV-19 vaccine for COVID-19, has announced that it will trial a combination of its drug and the Sputnik V vaccine developed by Russia’s Gamaleya Institute by the end of the year.
With UK and Russian scientists to work together, the dea is to see if the combination would result in better protection for recipients. Both vaccines are based on a modified version of the common cold virus “adenovirus”.
"Being able to combine different COVID-19 vaccines may be helpful to improved protection and/or to improve vaccine accessibility. This is why it is important to explore different vaccine combinations to help make immunisation programmes more flexible, by allowing physicians greater choice at the time of administering vaccines," AstraZeneca said in a statement on Friday.
“The decision by AstraZeneca to carry out clinical trials using one of two vectors of Sputnik V in order to increase its own vaccine’s efficacy is an important step towards uniting efforts in the fight against the pandemic,” said Kirill Dmitriev, chief executive of the Russia Russian Direct Investment Fund (RDIF) which is funding the Sputnik-V vaccine. “We hope that other vaccine producers will follow our example," he added.
The idea of combining the vaccines is based on the principle of “heterologous prime-boost”, where, instead of giving the same vaccine twice as booster shots, different vaccines triggering the same antibodies can be administered. The World Health Organisation had, in a 2014 technical consultation, noted that such a combination was known to "greatly increase both antibody and T cell immunogenicity when performed using certain vector combinations, above repeated dosing with the same vaccine candidate."
The Oxford vaccine was found to have had an average efficacy of 70.4 per cent—with a double-dose regime generating efficacy of just 62 per cent while those who received a half-dose regime had a 90 per cent efficacy.
The Sputnik V vaccine, meanwhile, was claimed to have had a 91.4 per cent efficacy.
Both the Oxford and Gamaleya vaccines are undergoing trials in India. Indian drugmaker Hetero has agreed to produce over 100 million doses of the vaccine, while the Serum Institute of India had planned to have as many doses of the Oxford vaccine available by December itself.