New study finds repeated Covid-19 vaccines are safe for your metabolism

Business Standard

29-04-2025

"Booster Covid-19 shot? Is that really okay for my body?" If that thought has crossed your mind, you are not alone. Many of us have quietly wondered what these repeated vaccines did inside us. And now, a new study might just put our minds at ease.
Researchers from Murdoch University in Australia conducted a 16-month-long study tracking how repeated Covid-19 vaccinations like the Pfizer-BioNTech and AstraZeneca vaccines affect the body — not just in terms of immune response, but also deeper changes in inflammation and metabolism. The study, titled Longitudinal study on immunologic, lipoproteomic, and inflammatory responses indicates the safety of sequential Covid-19 vaccination, was recently published in the J ournal of Molecular Medicine.
Their conclusion? No lasting side effects on the body's internal systems.
The researchers measured antibodies and checked over 130 health markers, including immune proteins (cytokines), cholesterol patterns, and small molecules in the blood. These tell us a lot about how the body is functioning behind the scenes.
They followed 33 healthy adults who received two to four doses of either the Pfizer-BioNTech or AstraZeneca vaccine. Blood samples were taken before and after each shot, and then followed up for over a year.
'The results showed no meaningful impact on key health indicators, including inflammatory markers, cardiovascular risk factors, and molecules involved in energy metabolism. Our findings provide insights into the safety of repeated Covid-19 vaccinations,' the study found.
Covid vaccine side effects show no link to long-term metabolic harm
While most participants reported mild side effects like a sore arm or feeling tired for a day or two, the researchers found no long-term changes in their metabolism. Even short-term fluctuations, like a temporary rise in a chemical called glutamic acid, returned to normal quickly.
Dr Subhashree Samantaray, Associate Consultant – Infectious Diseases at Manipal Hospitals, Bhubaneswar, clarifies, "The slight increase in glutamic acid after the third vaccine dose is not of medical concern. The study also tracked the glutamine to glutamate ratio — a more valid marker of metabolic stress — and found it holding steady. This balance indicates that the metabolic system kept everything well-regulated. These changes are routine and do not signal any long-term risks or dysfunction."
Interestingly, over 95 per cent of the samples from vaccinated people resembled those of completely healthy, uninfected individuals. Only a small fraction (5 per cent) resembled profiles seen in people with mild Covid-19 — mostly due to actual virus exposure, not the vaccine.
How repeated Covid vaccinations affect immune response and inflammation
A spike in a protein called IP10, which plays a role in immune responses, was seen briefly after the third shot. But this, too, was well within normal limits and quickly subsided.
Dr Samantaray explains why this isn't a concern, "A temporary elevation in cytokines such as IP10 is exactly what the body should be doing to fend off a first-encountered infection. It's a controlled, transient immune response that returned to baseline in a few days — well within the healthy range. There was no indication of prolonged inflammation or immune abnormalities."
Why long-term Covid vaccine safety studies still matter
Since the start of the SARS-CoV-2 pandemic, over 775 million cases and 7 million deaths have been recorded worldwide. While most patients have recovered, many face lasting effects. Since December 2020, over 13.6 billion Covid-19 vaccine doses have been administered. Vaccination has sharply reduced hospitalisations, deaths, and long Covid risk — though rare severe side effects such as inflammation of the brain and spinal cord (encephalomyelitis), and inflammation of the heart muscle (myocarditis), have emerged.
The withdrawal of the Oxford-AstraZeneca vaccine from the market highlights the need for continued research into the immunological, inflammatory, and metabolic effects of Covid-19 vaccines, both in the short and long term.
'Our findings show that repeated vaccination supports strong immunity without burdening the body's metabolic or inflammatory systems,' said the authors of the study.