AZD1222 was co-invented by Oxford University and its spin-out company Vaccitech.
The recombinant adenovirus vaccine, which was licensed by AstraZeneca in May 2020, was tolerated by the participants with no early safety concerns observed in the COV001 trial.
The early-stage trial evaluated a single dose of AZD1222 in comparison to MenACWY, a meningococcal conjugate vaccine in 1,077 healthy adults aged between 18 and 55 years.
AstraZeneca said that the COV001 trial demonstrated that a single dose of the recombinant adenovirus vaccine after a month of its administration helped in increasing the antibodies to the SARS-CoV-2 virus spike protein by four times in 95% of participants.
A T-cell response was induced in all the participants by the vaccine candidate, which was maintained two months after vaccination, as per the interim results. The peak response was noted by day 14, said AstraZeneca.
COV001 trial co-author Andrew Pollard said: “The interim Phase I/II data for our coronavirus vaccine shows that the vaccine did not lead to any unexpected reactions and had a similar safety profile to previous vaccines of this type.
“The immune responses observed following vaccination are in line with what we expect will be associated with protection against the SARS-CoV-2 virus, although we must continue with our rigorous clinical trial programme to confirm this.”
AstraZeneca revealed that 91% of participants were found to have neutralising activity in their body against the SARS-CoV-2 virus, a month after being administered with the AZD1222 vaccine. The same was noted in all the ten participants who were given a second dose of the vaccine after a gap of one month from the first dose.
According to the pharma major, the levels of neutralising antibodies observed in participants who were subjected either one or two doses of the recombinant adenovirus vaccine had an identical range to those seen in recovered Covid-19 patients.
The pharma major said that phase II/III clinical trials of the investigational Covid-19 vaccine are currently in progress across the UK, Brazil, and South Africa and are due to commence in the US.
The late-stage will determine the efficacy of the AZD1222 vaccine in protecting from Covid-19 and also in gauging safety and immune responses across various age groups and at multiple doses, said AstraZeneca.
AstraZeneca biopharmaceuticals R&D executive vice president Mene Pangalos said: “We are encouraged by the Phase I/II interim data showing AZD1222 was capable of generating a rapid antibody and T-cell response against SARS-CoV-2. While there is more work to be done, today’s data increases our confidence that the vaccine will work and allows us to continue our plans to manufacture the vaccine at scale for broad and equitable access around the world.”