Oxford COVID Vaccine Prompts Immune Response in Older People in Early Results Welcomed by Scientists
An experimental vaccine against COVID being developed at the University of Oxford has been found to be safe and trigger an immune response in older people, according to preliminary data.
The news comes after pharmaceutical companies Pfizer and Moderna recently announced positive results from their own COVID vaccine trials, and was welcomed by scientists as older people are at particular risk from the disease. Due to their waning immune systems, vaccines sometimes do not work as well in this demographic.
Results for the Oxford phase II trial published in the journal The Lancet showed the vaccine, named ChAdOx1 nCoV-19, triggered a similar immune response in older and younger people after a booster dose.
However, older people tolerated the shot better, and were less likely to experience side effects such as pain at the site of injection, feeling feverish, muscle ache, and headache. The vaccine did not cause any serious side effects.
The study focused on 560 healthy adults, including 160 aged between 18-55 years old, 160 aged 56-69, and 240 above 70. They were separated into 10 groups and randomly assigned either the experimental COVID vaccine or a control vaccine.
All of the participants were healthy, did not have comorbidities and were not frail. This is because the volunteers were recruited when the U.K. was under lockdown for COVID and vulnerable people were told to self-isolate.
Researchers checked the immune responses of participants in the first, second, and fourth weeks following their first shot of the vaccine, and did the same for a second booster shot. They noted whether the vaccine had activated different arms of the immune system, including antibodies against a spike that the coronavirus uses to invade the body.
Fourteen days after the first shot was given, a part of the immune system that tracks down and kills infected cells—called T cells—was triggered, and peaked at this time. The team also found the vaccine induced neutralizing antibodies 14 days after the second dose was administered. Additionally, the vaccine prompted the creation of antibodies against the coronavirus 28 days after a single dose, with the effect heightened 28 days after the booster dose.
The authors acknowledged their findings were limited as the oldest participants were aged between 73-74, on average, and did not have underlying health problems. This means the results may not relate to a wider population.
Phase III trials will investigate these findings in a larger population, and see if the vaccine protects against being infected by the coronavirus, including in people with co-morbidities.
Professor Andrew Pollard of the University of Oxford who led the study said in a statement: “Immune responses from vaccines are often lessened in older adults because the immune system gradually deteriorates with age, which also leaves older adults more susceptible to infections. As a result, it is crucial that COVID-19 vaccines are tested in this group who are also a priority group for immunisation.”
Co-author Dr. Maheshi Ramasamy of the University of Oxford said in a statement the team hopes their vaccine will protect “some of the most vulnerable people in society, but further research will be needed before we can be sure.”
Scientists who did not work on the study welcomed the results. Deborah Dunn-Walters, chair of the British Society for Immunology COVID-19 and Immunology taskforce, and professor of Immunology at University of Surrey, said: “While this is an ongoing study, the initial results are encouraging.
“If the immune measures recorded in the phase II part of this study correlate with protection from SARS-CoV-2 [coronavirus], then we would expect positive outcomes from the phase III trial.”
A “much larger” phase III trial is now needed to “thoroughly assess that the safety and effectiveness profile of this vaccine for widespread use against SARS-CoV-2.”
Michael Head, senior research fellow in global health at the University of Southampton, U.K., said the research was “well-conducted” and the study “shows us that this candidate has a good safety record.”
That it generated an immune response in all age groups, including the over 70s, was “good news,” he said.
Head said: “This research is not an announcement that the vaccine is ready to be licensed and rolled out, but it is further promising research in the efforts to development a successful COVID-19 vaccine.”
Gillies O’Bryan-Tear, chair of policy and communications at the Faculty of Pharmaceutical Medicine, U.K., compared the results to those of phase III trials by Moderna and Pfizer.
“It will be important to know the efficacy results which will show how many people were protected from getting COVID illness—but the number of people in this trial is relatively small, and so the number of COVID infections may have been too low to report on this.
“By comparison, the interim results from the Pfizer and Moderna trials reported on nearly 44,000 and 30,000 study participants respectively, which yielded 94 and 95 COVID patients respectively.”
O’Bryan-Tear said he was “struck by the low number of ethnic minority patients in this study.” He said: “They also excluded frail patients, deliberately, although they are being included in the phase III trial. I hope the larger phase III trial will have a more ethnically diverse patient population, and it should have, because it is being conducted in Brazil amongst other countries.”