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
The Surprising Origin of a Deadly Hospital Infection
C. diff might not originate from external transmission but rather from within the infected patient themselves. Hospital staff dedicate significant effort to safeguard patients from infections during their hospital stay. Through practices ranging from [...]
Google AI breakthrough – huge step in finding genes that cause diseases
Google says it has made a significant step in identifying disease-causing genes, which could help spot rare genetic disorders. A new model named AlphaMissense is able to confidently classify 89 per cent of all [...]
New Study: Everyday Pleasures Can Boost Cognitive Performance
MINDWATCH study reveals cognitive peaks with everyday pleasures. Listening to music and drinking coffee are the sorts of everyday pleasures that can impact a person’s brain activity in ways that improve cognitive performance, including [...]
Moderna reveals new highly targeted COVID-19 vaccine mRNA-1283
Moderna has developed a new and improved version of its COVID-19 vaccine. The unique formulation (mRNA-1283) reduces the vaccine's content from the full-length SARS-CoV-2 spike protein to a narrowly focused encoding of just two [...]
New nanotech weapon takes aim at hard-to-treat breast cancer
Breast cancer in its various forms affects more than 250,000 Americans a year. One particularly aggressive and hard-to-treat type is triple-negative breast cancer (TNBC), which lacks specific receptors targeted by existing treatments. The rapid [...]
Scientists upcycle plastics into liquids that can store hydrogen energy
Scientists from Nanyang Technological University, Singapore (NTU Singapore) have created a process that can upcycle most plastics into chemical ingredients useful for energy storage, using light-emitting diodes (LEDs) and a commercially available catalyst, all [...]
Yale Scientists Uncover How the Immune System Can Alter Our Behavior
The mere scent of seafood can severely sicken those allergic to it — and therefore they are more likely to avoid it. Similarly, individuals who experience food poisoning from a specific dish tend to [...]
Whirlwind Tech – The Future of Energy-Efficient Spintronics Computing
Researchers in Germany and Japan have been able to increase the diffusion of magnetic whirls, so-called skyrmions, by a factor of ten. In today’s world, our lives are unimaginable without computers. Up until now, [...]
Omicron’s Silver Lining: Significantly Lower Risk of Long COVID
Omicron infections have a lower risk of long COVID than earlier variants, according to a study analyzing data from 11,000 participants. The risk of developing long COVID is significantly lower following an infection with [...]
The Hidden Mechanism Connecting Diabetes and Cancer
Researchers have discovered that insulin resistance, typically linked with type 2 diabetes, is also present in cancer patients and can accelerate the spread of the disease. In the 1920s, scientists found that the urine [...]
Scientists Unveil Urea’s Secret Role in the Origin of Life
Scientists from ETH Zurich and the University of Geneva have developed a new technique that allows them to observe chemical reactions taking place in liquids at extremely high temporal resolution. This innovation enables them to track how molecules [...]
Viagra Lowers Alzheimer’s Risk by Almost 70%, Early Study Finds
Research published recently suggests that Pfizer’s erectile dysfunction drug Viagra can decrease the risk of developing Alzheimer’s disease by up to 69 percent. The research, which was published in Nature, found that the medication has [...]
Future of Medical Imaging: Advanced AI Can Tell Your True Age by Looking at Your Chest
An AI-powered model utilizes chest X-rays to help develop biomarkers for aging. What if determining “your age” was based on your chest rather than your face? Scientists from Osaka Metropolitan University have crafted an [...]
Ultra-sensitive biosensors detect cancer in a blood test
Cancer biomarkers circulating in body fluids can be used for diagnosis and treatment monitoring. However, current detection technology lacks the required sensitivity, limiting biomarker use in clinical applications. Colorectal cancer is the second most [...]
Viruses cause 200+ diseases. This one drug may be able to treat them all.
By taking aim at a process common across many viruses, the drug could one day stop any number of known viruses — and new ones. t’s about as audacious an idea as you can [...]
Scientists Identify Potential Treatment for Rare and Devastating Lung Disease
The findings could lead to a cure for LAM. Researchers from the University of Cincinnati may have identified a potential treatment for lymphangioleiomyomatosis (LAM), a rare lung condition resembling cancer found predominantly in women of reproductive [...]