Photo credit: www.sciencedaily.com
Recent research from Sydney provides compelling reasons for receiving booster vaccinations in the same arm as the initial dose, showing that this approach can enhance immune response efficiency. The study, conducted by the Garvan Institute of Medical Research along with the Kirby Institute at UNSW Sydney, was published in the journal Cell, shedding light on potential improvements for future vaccination strategies.
The team discovered that administering a vaccine primes specialized immune cells, known as macrophages, within lymph nodes. These primed macrophages subsequently position memory B cells more effectively, leading to a quicker and more potent response to booster shots when given in the same arm.
Findings derived from mice experiments and further validated in human subjects pave the way for refined vaccination strategies and offer a novel method for boosting vaccine effectiveness.
“This groundbreaking discovery enhances our understanding of how the immune system organizes itself to better respond to external threats. Nature has devised a remarkable system, and we are just beginning to grasp its complexities,” commented Professor Tri Phan, Director of the Precision Immunology Program at Garvan and co-senior author.
Scientia Professor Anthony Kelleher, Director of the Kirby Institute and co-senior author, emphasized the significance of the study: “A unique aspect of our work lies in our ability to comprehend the rapid development of effective vaccine responses. We achieved this by dissecting complex biological interactions in mice and later demonstrating similar results in humans, all localized at the lymph node, the site where vaccine responses are generated.”
Impact of Vaccination Location
Vaccination involves introducing a harmless version of a pathogen—referred to as a vaccine antigen—into the body, which is processed through lymph nodes. These nodes act as immune ‘training camps,’ preparing the body to combat actual infections. Previous research indicated that memory B cells, essential for generating antibody responses when faced with returning infections, reside in the lymph node nearest the injection site.
Utilizing advanced intravital imaging techniques at Garvan, the research team found that memory B cells migrate toward the outer layer of local lymph nodes and interact closely with resident macrophages. When a booster is administered in the same area, these primed macrophages efficiently capture the antigen, activating memory B cells to produce high-quality antibodies.
“While macrophages are widely recognized for engulfing pathogens and eliminating dead cells, our study reveals that those located in lymph nodes near the injection site are crucial in organizing an effective vaccine response upon subsequent doses. Thus, the site of vaccination is vitally important,” noted Dr. Rama Dhenni, the study’s co-first author, who conducted this research as part of his PhD program at Garvan.
Clinical Validation of Findings
In order to assess the applicability of their animal research to human vaccination, the Kirby Institute team carried out a clinical study involving 30 volunteers receiving the Pfizer-BioNTech COVID-19 mRNA vaccine. Of these participants, twenty received their booster in the same arm as their initial shot, while ten were administered the second dose in the opposite arm.
“Those vaccinated in the same arm developed neutralizing antibodies against SARS-CoV-2 at a significantly faster rate, within the first week post booster,” stated Ms. Alexandra Carey-Hoppé, co-first author and PhD student from the Kirby Institute.
“Antibodies generated in the same arm group also exhibited greater effectiveness against variants such as Delta and Omicron. Although both groups reached similar antibody levels by four weeks, the expedited protection in the initial weeks could be critical during an outbreak,” highlighted Dr. Mee Ling Munier, co-senior author and leader of the Vaccine Immunogenomics group at the Kirby Institute.
“If you’ve received your COVID vaccinations in different arms, there’s no need for concern—as our findings indicate that the difference in protection diminishes over time. However, the initial weeks of enhanced protection may hold significant collective benefits, particularly during a pandemic. The same-arm approach could potentially accelerate herd immunity, especially crucial for quickly mutating viruses where prompt response is essential,” she added.
Future Implications
The implications of this research not only hint at possible updates to vaccination guidelines but also suggest opportunities for improving overall vaccine efficacy.
“By understanding how to replicate or boost the interactions between memory B cells and macrophages, we can work towards developing next-generation vaccines that might require fewer booster doses,” remarked Professor Phan.
This research received support from the Australian National Health and Medical Research Council.
Professor Tri Phan is also a Conjoint Professor at St Vincent’s Clinical School, Faculty of Medicine and Health, UNSW Sydney.
Source
www.sciencedaily.com