The COVID-19 vaccine candidate being developed by the Oxford university and AstraZeneca is safe, well-tolerated, and immunogenic (capable of inducing an immune response), according to preliminary data from early stages of human trials.
The data published by medical journal The Lancet highlights that “ChAdOx1 nCoV-19 showed an acceptable safety profile, and homologous boosting increased antibody responses. These results, together with the induction of both humoral and cellular immune responses, support large-scale evaluation of this candidate vaccine in an ongoing phase 3 programme.”
Phase 1/2 trial had recruited 1,077 healthy adults in April and preliminary data found that experimental vaccine induced both strong antibody and T-cell immune responses up to day 56 of the ongoing trial. Antibody response offers short-term immunity to fight off the infection and the T-cells are responsible for providing long-term immunity. Levels of T-cells peaked 14 days after vaccination and antibody levels peaked after 28 days.
Alternatively, a subgroup study of 10 participants also showed vaccine response may be even greater after the second dose.
“These antibody responses were present in all participants who had a booster dose of the vaccine,” according to the journal.
There were no serious adverse events related to ChAdOx1 nCoV-19, according to the publication. The experimental vaccine caused minor side-effects like fever, chills and muscle pain in about 60 percent of participants, but it is more often in those who got a control meningitis vaccine. The side -effects were reduced by use of prophylactic paracetamol. The vaccine candidate has moved rapidly into larger-scale studies versus other competing vaccine candidates and has now presented first set of encouraging results on efficacy.
The Lancet Medical Journal Editor-In-Chief Richard Horton told Bloomberg, “I don’t think this study could have gone any better. It showed both safety and immunogenicity that was expected to be studied in Phase 1. Now phase 3 will test the vaccine in high risk people.”
Horton said he anticipated the vaccine to be made available in first 6 months of 2021, if phase 3 trials are completed by the end of 2020. Currently, large-scale Phase 3 trials are underway in Brazil, South Africa, and the UK and will evaluate vaccine efficacy in diverse populations.
The UK has already ordered 100 million doses of the vaccine. AstraZeneca has signed manufacturing tie-ups with multiple vaccine manufacturers, including Indian firm Serum Institute of India. AstraZeneca has already committed to making 2 billion doses, with nearly half coming from the Indian partner.
Adar Poonawalla, CEO of Serum Institute of India (SII), said, “The trials have shown promising results and we are extremely happy about it. We will be applying for the licensure trials to the Indian regulator in a week's time. As soon as they grant us permission, we will begin with the trials for the vaccine in India. In addition, we will soon start manufacturing the vaccine in large volumes.”
The experimental vaccine of Oxford – Astrazeneca, ChAdOx1 nCoV-19, combines genetic material from the coronavirus with a modified adenovirus that is known to cause infections in chimpanzees. This is one of the 23 potential COVID-19 vaccines that are being tested in clinical trials, according to the World Health Organization.
Experts highlight that the encouraging data has raised the prospect that a COVID-19 vaccine could be available by the end of this year. However, these are early results of Phase 1 & 2 human trials and may not be enough to conclusively prove efficacy and data from the ongoing larger trials will provide more input on whether the vaccine offers protection and for how long.
The UK’s Prime Minister Boris Johnson in a tweet said, “This is very positive news. A huge well done to our brilliant, world-leading scientists & researchers at University of Oxford. There are no guarantees, we’re not there yet & further trials will be necessary - but this is an important step in the right direction.”
Researchers are now recruiting older age groups with comorbidities, health-care workers, and those with higher risk for SARS-CoV-2 exposure. The study will now expand to assess efficacy, safety, and immunogenicity of ChAdOx1 nCoV-19 given as a single-dose or two-dose administration regimen in further trials conducted in the UK and overseas.
“We will also evaluate the vaccine in children, once sufficient safety data have been accumulated in adult studies.”
The 1,077 participants recruited in this study will also be followed up for at least one year and further safety, tolerability, and immunogenicity results will be reported when data are available.