The first results of separate British and Chinese candidate coronavirus vaccines reported on Monday showed promising signs of immunity and no serious side effects.
The first results of 1,077 volunteers in a study from the University of Oxford and 508 adults in the CanSino Biologics study conducted in Wuhan, China, are encouraging as both studies move toward widespread testing of the vaccines in tens of thousands of volunteers, experts said.
“Overall, the results of both trials are very similar and promising,” vaccine experts at the Johns Hopkins Bloomberg School of Public Health, Naor Bar-Zeev and William Moss wrote in a comment accompanying the studies. “The safety signs from these two important trials are reassuring.”
One-month trials in healthy volunteers produced “neutralizing” antibodies, in 90% of the Oxford participants and 85% of the Wuhan, seen as a marker of an effective vaccine. They also led to the development of longer-lived T cells that respond to inoculations, a marker of a long-term immune system response to a virus.
“Both the Oxford and Beijing vaccines induce a high-frequency T cell antiviral response, which looks promising,” Imperial College professor of medicine Daniel Altmann told BuzzFeed News.
Both vaccines are based on harmless viruses designed to contain parts of SARS-CoV-2 spike proteins to trigger an immune response after injection, a new vaccination approach developed against influenza and Ebola in the past decade. The Oxford University vaccine is being developed with AstraZeneca, part of Candidates for Operation Warp Speed, with the support of more than $ 1 billion from the U.S. Advanced Biomedical Research and Development Authority.
Tolerable fatigue, headache and arm tenderness were the only side effects reported by the volunteers, similar to other vaccines, according to the studies. In the Oxford trial, some participants received a second booster injection, reporting antibodies without any side effects or signs of a feared excessive immune response. The CanSino trial tested low-dose and moderate-dose inoculation, resulting in very similar immune responses, after an earlier small trial showed more side effects from high doses.
Less than a year after a global pandemic, key unanswered questions about the new coronavirus include how far candidates will completely avoid infection and transmission of SARS-CoV-2 to people, rather than simply limiting the severity of an infection. Another is whether vaccinations will be required each year.
Right now, three candidate coronavirus vaccines are in the final stages of phase 3 testing of tens of thousands of volunteers, according to the World Health Organization. Those three are candidates for the University of Oxford, one from a Chinese pharmaceutical company called Sinovac and one from Moderna in the United States. The candidate Sinovac is an inoculation with dead viral particles used in vaccines for decades, while the Moderna is a leading-edge “RNA vaccine” that sends genes for viral antigens that prepare the immune system to prevent infection.
Phase 3 candidates from Oxford and Siniovac have already started recruiting volunteers for the trials, while Moderna is expected to start before the end of July. Experts hope that by the end of the year these trials will determine whether vaccine candidates are safe and effective enough for the widespread inoculation of millions of people.
