July 21, 2020
Another vaccine candidate appears to safely induce an immune response against the coronavirus, according to preliminary results.
The candidate, developed by researchers at the University of Oxford and the pharmaceutical company AstraZeneca, is the latest hopeful sign that scientists can identify a vaccine capable of halting the COVID-19 pandemic.
A clinical trial of 1,077 healthy adults found that the vaccine could elicit a strong antibody and T cell immune response up to day 56 of the study. Data from a subgroup of 10 participants also suggests that a second dose would trigger an even greater reaction to the SARS-CoV-2 virus.
No serious adverse reactions to the vaccine were reported, but it did cause minor side effects more frequently than the meningitis vaccine given to the control group. The findings were published Monday in The Lancet.
Last week, Moderna released the promising results of its vaccine, which is slated to begin a Phase 3 trial shortly. Several other vaccine candidates also have advanced to Phase 3 trials, including one made by Pfizer and BioNTech.
The Oxford vaccine has already creating excitement, despite the need for additional studies. The U.S. and British governments and the European alliance have already placed their orders for millions of doses.
The vaccine was able to trigger a response to the coronavirus on two fronts. First, it provoked a T cell response within 14 days after vaccination. T cells find and attack the coronavirus as it invades cells.
It also triggered the production of antibodies, the immune system's second line of defense against invaders, within 28 days after vaccination.
"The immune system has two ways of finding and attacking pathogens – antibody and T cell responses," said researcher Andrew Pollard of the University of Oxford, the study's lead author. "This vaccine is intended to induce both, so it can attack the virus when it's circulating in the body, as well as attacking infected cells. We hope this means the immune system will remember the virus, so that our vaccine will protect people for an extended period.
"However, we need more research before we can confirm the vaccine effectively protects against SARS-CoV-2 infection, and for how long any protection lasts."
The participants of the study, who were between the ages of 18 and 55, received either the new vaccine or the meningitis vaccine. They then were asked to give blood samples and undergo clinical assessments to determine the safety and efficacy of the vaccine.
Fatigue and headache were the most common side effects. Others included pain at the injection site, muscle ache, chills and fever. A subgroup that was asked to take acetaminophen before or after vaccination reported reduced side effects. The participants in the study will continue to be followed for a year.
The next step is to conduct further clinical studies, including in older adults, to confirm that the vaccine does confer protection. A Phase 2 trial is happening in the United Kingdom and a Phase 3 trial in the U.K., Brazil and South Africa. The U.S. also plans on conducting clinical trials on the vaccine later this summer.
According to the World Health Organization, there are 23 COVID-19 vaccines in human trials.