Updated: November 20, 2020 9:52:14 am
“Further evaluation of the efficacy of this vaccine is warranted in all age groups and individuals with comorbidities,” the researchers said.
The Oxford-AstraZeneca Covid-19 candidate vaccine has triggered a robust immune response in older adults in phase 2 clinical trials, demonstrating its potential utility in protecting a section of the population that is among those most at risk of contracting it. the new coronavirus disease.
Preliminary findings published in the medical journal The Lancet show that ChAdOx1 nCov-2019, a technical name for the candidate vaccine developed by scientists at the University of Oxford and the British-Swedish pharmaceutical giant AstraZeneca, is safe, well tolerated, and produces an immune response. similar in all age groups after a booster shot.
Importantly, “ChAdOx1 nCoV-19 appears to be better tolerated in older adults than in younger adults …”, the study said, “and has similar immunogenicity in all age groups after a booster dose.”
“Further evaluation of the efficacy of this vaccine in all age groups and individuals with comorbidities is warranted,” the researchers said.
Dr Maheshi Ramasamy, a researcher at the Oxford Vaccine Group, said: “Older adults are a priority group for Covid-19 vaccination, because they have a higher risk of severe disease, but we know they tend to have worse responses to vaccine.
“We were pleased to see that our vaccine was not only well tolerated by older adults; it also stimulated immune responses similar to those seen in younger volunteers. The next step will be to see if this translates into protection against the disease itself. “
These preliminary findings are important for India, as this candidate vaccine is undergoing phase 3 clinical trials in the country by Pune-based vaccine manufacturer Serum Institute India (SII) and the Indian Council for Medical Research (ICMR). . SII has already manufactured 40 million doses of the candidate vaccine under a manufacturing and storage-at-risk license from the main national regulator, the Controller General of Drugs of India (DCGI), and will supply a large portion of the national requirements of the India for the vaccine.
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Findings reported in The Lancet (Safety and Immunogenicity of ChAdOx1 nCoV-19 Vaccine Given as a Primary Booster Regimen in Young and Elderly Adults (COV002): A Single-blind, Randomized, Controlled, Phase 2/3 Trial) Give Hope that the vaccine will help the country’s large population of older adults against the virus.
The Oxford researchers have said that “early efficacy readings” from ongoing phase 3 trials are “possible in the next few weeks.” Pfizer-BioNTech and Moderna have reported greater than 90% efficacy for their mRNA vaccine candidates in the early results of phase 3 trials. Russian candidate Sputnik V, manufactured by a Moscow-based laboratory, has also reported of excellent phase 3 trial results. Although none of these studies have been peer-reviewed yet, hopes have been raised for the imminent arrival of a vaccine that can defeat the virus that has sickened more than 56 million people and killed to 1.35 million worldwide so far.
During the phase 2 trial, the Oxford-AstraZeneca vaccine was evaluated in 560 healthy adult volunteers in the age groups 18-55 years, 56-69 years and older than 70 years, who received two doses of ChAdOx1 nCoV-19, or a MenACWY placebo vaccine.
“Our findings show that the ChAdOx1 nCoV-19 vaccine was safe and well tolerated with a lower reactogenicity profile (ability to produce adverse reactions) in older adults than in younger adults. Immunogenicity (ability to generate an immune response) was similar in all age groups after a booster vaccination, ”the study said.
“Most of the reported local and systemic adverse events” were of mild to moderate severity, the researchers said, in line with their previous phase 1 study. Serious adverse events seen during the trial “were considered to be unrelated to the study vaccines,” they said.
“Local and systemic reactions were more common in participants who received ChAdOx1 nCoV-19 than those who received the control vaccine, and similar in nature to those previously reported (injection site pain, feeling of fever, pain muscle, headache), but were less common in older adults (age = 56 years) than in younger adults.
“The severity of reported symptoms in the standard dose groups was reduced after the booster vaccination, and only one (1%) of 127 participants reported a severe reaction compared to seven (5%) of 128 participants after the primary vaccination, “the study said.
When detecting a pathogen, the human body produces two types of responses within the adaptive immune system: humoral or antibody-mediated immunity and cellular immunity that occurs within the infected cell and is mediated by T lymphocytes.
The candidate vaccine induced a “specific antibody response” to the peak SARS-CoV-2 glycoprotein after a single dose in all age groups, and specifically, the neutralizing antibody titers “after a booster dose were similar. in all age groups, “according to the study. . T-cell responses “peaked 14 days after the main vaccination,” he said.
“The robust humoral and cellular immune responses elicited in our older adult population were encouraging, as several studies have shown that declines in immune function with age lead to decreased immune responses to vaccines.”
Dr Angela Minassian, Oxford University Researcher and Honorary Infectious Disease Consultant, said: “Inducing robust immune responses in older adults has been a long-standing challenge in human vaccine research. Showing that this vaccine’s technology is capable of inducing these responses, in the age group most at risk for severe Covid-19 disease, offers hope that the vaccine’s efficacy will be similar in young and older adults. “
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