The interim data analysis of phase-3 data of Oxford/AstraZeneca COVID-19 candidate vaccine (ChAdOx1 nCoV-2019) showed higher efficacy in preventing COVID-19 disease, according to Oxford University press release.
The early analysis of a regimen, where a half-dose prime and a full-dose booster was used, reduced the virus transmission, said the investigators. This was based on observed reduction in asymptomatic infections in participants who received the vaccine in the phase-3 trial.
Two doses of the vaccine were given in two different regimens during the study which showed different efficacies. In the case of the regimen where a halved dose was used as a prime (first dose) followed by a standard dose of a booster, the efficacy was 90%. However, where full doses (standard dose) were used both for the prime and booster doses, the efficacy was only 62%. The combined analysis from both dosing regimens resulted in an average efficacy of 70.4%.
The results were drawn based on 131 COVID-19 cases seen in phase-3 trial. No serious safety events related to the vaccine nor hospitalised or severe cases were seen in anyone who received the Oxford vaccine, the release says.
The Oxford vaccine (ChAdOx1 nCoV-19) is made from a virus, which is a weakened version of an adenovirus (common cold virus), that has been genetically changed so that it is impossible for it to grow in humans.
The Oxford vaccine, unlike the Pfizer’s mRNA-based COVID vaccine, can be stored at just 2-8 degree C, thus making vaccine distribution and administration easy, without requiring any upgradation to existing cold storage system. This will be particularly important in the developing countries, where ultracold storage systems are non-existent. Pfizer’s vaccine BNT162b2 requires -70 to -80 degree C cold storage.
“These findings show that we have an effective vaccine that will save many lives. Excitingly, we’ve found that one of our dosing regimens may be around 90% effective and if this dosing regimen is used, more people could be vaccinated with planned vaccine supply,” said Professor Andrew Pollard, Director of the Oxford Vaccine Group and Chief Investigator of the Oxford Vaccine Trial.
The interim analysis was carried out on data collected as on November 4, when the trial had reached the pre-determined target for the first interim analysis. The trial had enrolled over 24,000 participants from diverse racial and geographical groups in the UK, Brazil and South Africa.
Oxford will now support AstraZeneca in submitting both the interim phase-3 efficacy data and the extensive safety data to all regulators across the world, including in the UK, Europe and Brazil for independent scrutiny and product approval, including for emergency use, according to the release.
In India, the Serum Institute is manufacturing the vaccine and also carrying out clinical trials in the country. The company has already started manufacturing the vaccine and would produce 50-60 million doses of the vaccine candidate every month from January, according to Suresh Jadhav, Executive Director of Serum.