Scientists identify key differences in immune responses to the AstraZeneca and Pfizer vaccines.
A recent study conducted by a team from SAHMRI and Flinders University in Australia has revealed significant variations in the way the AstraZeneca and Pfizer COVID-19 vaccines affect the immune system. The findings, published in Cell Reports Medicine, are part of the COVID-19 Vaccine Immune Responses Study (COVIRS) and were based on the analysis of the immune responses of 102 adults of various ages residing in South Australia, where there was no SARS-CoV-2 community transmission at the time of the study.
The participants in the study had their blood samples collected immediately after receiving each dose of either the Oxford/AstraZeneca or Pfizer/BioNTech COVID-19 vaccine, in order to evaluate their early immune response. Further tests were conducted 28 days after each immunization to measure the activity of B and T cells, both of which play a crucial role in the immune response. B cells produce antibodies, while T cells target and eliminate infected cells.
The vaccines are alike in the sense that they induce the immune system to recognize and protect against the SARS-CoV-2 virus, but they differ in how this is achieved. The Pfizer vaccine uses mRNA technology to induce host cells to produce the SARS-CoV-2 Spike protein, while the AstraZeneca vaccine uses a harmless virus (a chimpanzee adenovirus) to encode the Spike protein.
"After the first dose, we were surprised to find the Oxford/AstraZeneca vaccine elicits an unexpected memory-like response in the immune system, recognizing the vaccine as if it's something it's seen before," says Professor Lynn, from the College of Medicine and Public Health at Flinders University.
"This response is targeted against the adenovirus vector in the vaccine, not the Spike protein and the intensity of this response correlates with the expression of proteins that act as a pre-cursor to thrombosis, or blood clotting. While Vaccine-induced immune thrombotic thrombocytopenia (VITT) is an extremely rare side effect associated with the Oxford/AstraZeneca vaccine that none of the participants developed during the study, this research offers a potential explanation for the connection between the Oxford/AstraZeneca vaccine and the cases of VITT that have been reported."
The study also found those who'd only had two doses of the Oxford/AstraZeneca vaccine generally produced lower amounts of antibodies and less of a specialized type of T-cell that helps with antibody production; compared to those who had two doses of the Pfizer/BioNTech vaccine.
However, this was rectified once they had their third booster dose of an mRNA vaccine, illustrating the importance of booster doses. The study added evidence to the notion that COVID-19 vaccines offer some people more effective protection than others.
The reasons for this variability are not well understood, but Professor Lynn says age is a factor, with older people generally having a lower immune response after two doses. Fortunately, a third booster dose was highly effective at overcoming this. Immune responses induced immediately after vaccination predicted the subsequent B and T cell response to the vaccine measured a month later.
"One to two days after initial vaccination we measured gene expression responses in the blood which correlated with adaptive immune responses that mediate protection 28 days later," Professor Lynn says.
A further surprise to researchers was the finding that feeling unwell after a vaccine dose may in fact be linked to its effectiveness.
"People who showed symptoms of fatigue and fever immediately after the third dose were more likely to have better T-cell responses. T-cells play a vital role in vaccine efficacy as they can directly kill viral cells," Professor Lynn said.
Overall, this project has provided important new insights into the early immune responses to these vaccines and offers a greater understanding of how they work to protect against COVID-19.
News
Cancer’s Hidden Antioxidant Shield Helps It Escape the Immune System
Blocking an antioxidant protein that tumors use to suppress immune attacks improved cancer immunotherapy responses in mice. Cancer cells can release antioxidants that interfere with the immune cells trying to kill them. Researchers have [...]
Scientists Find a Berry Compound That Helps Muscle Cells Burn Fat
Pterostilbene, a compound found naturally in some foods, affects how skeletal muscles process fats by stabilizing a protein called PPARδ and increasing its signaling activity. Pterostilbene, a natural compound found in blueberries, grapes, and [...]
Two Hidden Forces Help Build the Human Brain Before Birth
Scientists have uncovered two surprising forces that help guide how the human brain forms before birth. Before birth, the human brain is shaped in large part by an unusual class of stem cells known [...]
Researchers Uncover a Hidden Trigger Behind Chronic Inflammation
The findings offer new insights that could help guide the development of future therapies. A protein called human resistin may help flip on one of the immune system’s most powerful inflammatory switches. Researchers at [...]
Scientists Have Uncovered Previously Hidden Microbial Activity on Human Skin
The most abundant microbes on your skin may not be the ones doing most of the work. Human skin supports vast communities of bacteria, fungi, and viruses that can influence its protective barrier, immune [...]
Brazilian Tree Compounds Fight COVID-19 on Multiple Fronts
Scientists found compounds in a Brazilian tree that hit SARS-CoV-2 on multiple fronts, revealing a promising new lead in the search for COVID-19 treatments. Researchers have found that galloylquinic acids extracted from the leaves [...]
Cutting Two Amino Acids Slowed Prostate Cancer in Mice
A newly identified link between amino acid metabolism and cholesterol production may help prostate tumors adapt to hormone therapy. Prostate cancer can find ways around treatments designed to deprive tumors of the hormones they [...]
Largest-Ever Physics Survey Raises New Doubts About Our Model of the Universe
Physicists around the world remain deeply divided on key mysteries of the universe, from dark matter to quantum gravity. The standard cosmological model failed to gain majority support, and no leading theory dominated the [...]
Scientists Just Overturned a 100-Year-Old Belief About Bacteria in the Lungs
New findings raise questions about the role of microbes living in the lungs. More than 35 trillion bacteria live throughout the human body, forming microbiomes in the gut, mouth, lungs, skin, and urogenital tract. [...]
GHCE Concept
From the preface of the book Global Health Care Equivalency in the Age of Nanotechnology, Nanomedicine and Artificial Intelligence, Edited by Frank Boehm: Since the publication of my first book (Nanomedical Device and Systems [...]
Novartis, Ionis drug failure spurs questions
Pelacarsen didn’t protect heart health despite lowering levels of a protein particle, “Lp(a),” in a large clinical trial — a result with important implications for cardiovascular drug research. Dive Brief: An RNA drug from [...]
New injectable treatment helps the brain rebuild after stroke
Biomedical engineers at Duke University have created an injectable biomaterial that may help the brain recover from damage left behind by an ischemic stroke. In experiments with mice, the material transformed the cavity created [...]
Scientists Discover a Hidden “Immune Organ” Inside the Skull
Researchers discovered lymph node-like immune hubs inside skull bone marrow that appear to act as rapid-response centers for the brain. For decades, the brain was thought to operate largely apart from the immune system. [...]
Engineered tRNAs and lipid nanoparticles target nonsense mutation cystic fibrosis
Researchers have developed a potential new approach for treating a form of cystic fibrosis caused by so-called nonsense mutations, combining chemically modified transfer RNAs with lipid nanoparticles designed to deliver the therapy directly to [...]
New pancreatic cancer drug carries a $39,800 monthly list price
A groundbreaking treatment for one of the most common forms of pancreatic cancer has been approved in pill form by the FDA. Revolution Medicines’ oral tablet daraxonrasib, branded as Rasonque, reduced the risk of [...]
Researchers Have Discovered a New Way To Reduce Chronic Nerve Pain
A cancer-linked protein called BRAF may help drive chronic nerve pain, and existing cancer drugs targeting it reduced pain sensitivity in preclinical models. Chronic nerve pain can persist long after an injury and often [...]
