According to research published this week in The Lancet journal, the Oxford/AstraZeneca COVID-19 vaccine AZD1222 is safe and effective at preventing the disease, as well as protecting against illness and death.
No severe cases and no hospitalizations were required more than 21 days after the first injection of the vaccine over the course of phase three clinical trials conducted on more than 20,000 people. The peer-reviewed study was an interim analysis for efficacy, based on 11,636 participants from Oxford’s trials in both the U.K. and Brazil. Some 131 symptomatic infections were acquired over the course of the investigation.
The vaccine demonstrated 70.4 percent overall effectiveness in preventing symptomatic COVID-19 cases for more than 14 days after receiving two doses of the vaccine. Different vaccine doses were pursued over the trial, though, with one demonstrating 62.1 percent effectiveness and another 90 percent.
The difference favored those given lesser doses. Volunteers given shots with half the strength than originally planned — a half dose followed by a full dose — proved the most effective at 70 percent, while those given two full doses experienced only 62 percent effectiveness.
“Today’s peer-reviewed publication enables a full disclosure of the Oxford programme interim analysis,” Pascal Soriot, CEO of AstraZeneca, said. “The results show that the vaccine is effective against COVID-19, with in particular no severe infections and no hospitalisations in the vaccine group, as well as safe and well tolerated. We have begun submitting data to regulatory authorities around the world for early approval, and our global supply chains are up and running, ready to quickly begin delivering hundreds of millions of doses on a global scale at no profit.”
The University of Oxford and Vaccitech created AZD1222 through a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus. Participants in this latest trial were pulled from diverse racial and geographic groups, and all were healthy or with stable underlying medical conditions. Most participants were under 55 years old. Researchers will continue to gather data for an upcoming primary analysis and beyond, allowing characterization of its efficacy over a longer period of time.
“In future analyses, with more data included as it becomes available, we will investigate differences in key subgroups such as older adults, various ethnicities, doses, timing of booster vaccines, and we will determine which immune responses equate to protection from infection or disease,” said Dr. Merryn Voysey, lead statistician at the Oxford Vaccine Group and study author.
Submission to regulatory agencies could allow the vaccines to meet temporary use or conditional approval in various locales. AstraZeneca is also pursuing an Emergency Use Listing from the World Health Organization, which would allow it an accelerated means of pursuing vaccine availability in low-income countries.
“Control of the pandemic will only be achieved if the licensing, manufacturing and distribution of these vaccines can be achieved at an unprecedented scale, and vaccination is rolled out to those who are vulnerable,” Andrew Pollard, Oxford professor and study lead author, said. “Our findings indicate that our vaccine’s efficacy exceeds the thresholds set by health authorities and may have a potential public health impact.”
A separate study, conducted by AstraZeneca rather than Oxford, is currently underway worldwide. AstraZeneca also expects to manufacture up to 3 billion doses of the vaccine in 2021 on a rolling basis.