Oxford-AstraZeneca vaccine shows positive results, up to 90% efficacy

Data from global trials to be submitted to the Indian regulator by the end of December

The AstraZeneca-Oxford vaccine candidate has shown positive results in an interim analysis of clinical trials in the UK and Brazil, with a vaccine efficacy of up to 90 per cent in different dosing regimens. 

Data from the global trials would be submitted to the Indian regulator by the end of December, and Serum Institute of India (SII), AstraZeneca’s manufacturing partner here, would submit the interim data from the Indian arm by then, sources said.  

“It is up to the Indian regulator to decide which dosage form it would approve for the Indian population. Data from all the dosage forms will be presented before the regulator,” a source said. The recruitment for the 1,600-volunteer Indian arm of the Covishield vaccine trial is over and the trial is in the last leg.

The regimen, with one half dose followed by a full dose after a month, has shown 90 per cent efficacy. This would enable manufacturing partners to supply more doses quicker. Pascal Soriot, chief executive officer, AstraZeneca, said: “On a half-dose basis, we will have double capacity to supply the initial doses.” The current 10-dose vial is suitable for filling the half doses as well. 

Professor Andrew Pollard, chief investigator of the Oxford Vaccine Trial at Oxford, said the results were not entirely ‘surprising’. “By giving a smaller dose, we are priming the immune system, preparing it to respond better,” he said. Scientists will now study the phenomenon in detail.

According to common expectation, two full doses are expected to produce the strongest immune response. However, for the AZD1222, or Covishield, when two full doses were given to volunteers one month apart, it showed a 62 per cent efficacy. The combined analysis from both the dosing regimens resulted in an average efficacy of 70 per cent. 

No serious safety events related to the vaccine have been confirmed. A total of 131 Covid-19 cases have been reported in the interim analysis. Covishield was well tolerated across both dosing regimens, the company said. The primary endpoint was to prevent Covid-19 and the vaccine was highly effective in that, the UK firm said. 

The interim data was pooled from Phase-2 and -3 trials in the UK and Brazil among 23,000 people. Clinical trials are also being conducted in the US, Japan, Russia, South Africa, Kenya, and Latin America with planned trials in other European and Asian countries. In total, the company expects to enrol up to 60,000 participants globally.

Pam Cheng, executive vice-president, global operations and IT, said they would start supplying by the end of this year. With around 20 partners, AstraZeneca can supply up to 3 billion doses globally next year, and at the peak it would have a capacity of 100-200 million doses per month. They have partners in India, Brazil, Russia and America.

Indian partner, SII, will be supplying 1 billion doses to AstraZeneca in 2021. Of this, around 50 per cent will be for India. SII will also supply 200 million doses of the Covishield and Novavax vaccine to Gavi, the vaccine alliance. 

SII, which would distribute the vaccine in India, has said the Covishield will be priced at Rs 250-300 per dose for the government, and Rs 500-600 per dose for the private market.