November turned out to be the month of good Covid-19 vaccine news. After the promising interim results of the Pfizer and Moderna Phase 3 trials, the results of the Oxford Vaccine Phase 2 trial have been published.
The Oxford Vaccine (ChAdOx1 nCoV-19) was administered to 560 people in two standard doses. The team reports in the journal Lancet that 14 days after the booster dose 208 out of the 209 participants that received both doses had neutralizing antibodies.
This is a very encouraging result. The researchers also stress that 240 participants were over the age of 70 and their immune responses were similar to younger people in this clinical trial as well as the results from the younger cohort from Phase I. This is a very important result given how older adults are one of the most-at-risk groups.
“Inducing robust immune responses in older adults has been a long-standing challenge in human vaccine research,” Dr Angela Minassian, Investigator at the University of Oxford and Honorary Consultant in Infectious Diseases said in a statement.
“To show this vaccine technology is able to induce these responses, in the age group most at risk from severe COVID-19 disease, offers hope that vaccine efficacy will be similar in younger and older adults.”
Another excellent piece of news is that the vaccine is well tolerated with side effects only around the injection site and only lasting for a short period of time. And it turns out that older adults are less likely to have local reactions where they got the injection and symptoms on the day of vaccination compared to younger people.
“Older adults are a priority group for COVID-19 vaccination, because they are at increased risk of severe disease, but we know that they tend to have poorer vaccine responses,” Dr Maheshi Ramasamy, Investigator at the Oxford Vaccine Group and Consultant Physician, explained.
“We were pleased to see that our vaccine was not only well tolerated in older adults; it also stimulated similar immune responses to those seen in younger volunteers. The next step will be to see if this translates into protection from the disease itself.”
ChAdOx1 nCov-2019 vaccine is currently undergoing its Phase 3 trial with 40,051 participants currently enrolled. The first interim results of efficacy readings for this trial are expected to be reported in the coming weeks. The vaccine uses a chimpanzee adenovirus which has been genetically modified to have the same external spike proteins as SARS-CoV-2, the virus behind Covid-19. This adenovirus doesn't infect humans but its presence trains our immune system to recognize these spike proteins as a danger.
