Left or right? In which arm should vaccines be injected? Left or right? In which arm should vaccines be injected?

Left or right? In which arm should vaccines be injected?

Researchers have studied different ways in which vaccines (since their appearance nearly two centuries ago) affect the body's immune system to launch a full-scale attack on pathogens.
But an important question has been preoccupying health experts around the world until now: in which arm should vaccines be injected?

In this regard, Marcel Kerlin, an infectious disease specialist from Oregon Health and Science University (OHSU), says: “This issue has not been widely studied, so we decided to investigate it.”

After analyzing the scientific literature on this topic, the research team found only 4 research papers, and the results were mixed.

One trial found that influenza vaccines given to 2-, 3-, and 4-month-old children in different arms resulted in higher antibody levels than when given in the same arm.

In the recent study, researchers at OHSU tested the antibody levels of 947 participants who received two doses of the “Covid-19” vaccine.

Half of the participants received the second dose of the vaccine in the same arm, while the other half received additional doses in the other arm. Four weeks after the second dose, antibodies to SARS-CoV-2 were 1.4 times higher in those who received the vaccine in the other arm.

Kerlin's team explained that when the vaccine is administered into the muscle, immune cells recognize the antigens contained in the drug and transport them to the lymph nodes for further immune response, which prepares the immune system against this antigen by sending the required signals.

Different sides of the body are associated with different lymph nodes, therefore, the body may be more careful by stimulating the immune response on both sides (arms).

“By switching between the arms, a memory is formed in two locations instead of one,” Kerlin explains. 

After just three weeks, the OHSU researchers noticed that vaccination in both arms began to show better results, and these benefits gradually improved, reaching their peak in the fourth week and continuing for several months after that.

The study was published in the Journal of Clinical Investigation.


Discovering a unique ability in the immune system to combat malaria

Researchers from the Australian National University (ANU) have discovered a unique ability of a group of immune system cells (atypical B cells, ABCs) to fight infectious diseases such as malaria.
This discovery provides new insight into how the immune system fights infection, and thus the ability to harness the body's natural defenses to fight malaria. ABCs could also be key to developing new treatments for chronic autoimmune diseases such as lupus.

Lead author Dr Shen Zhao, from the Australian National University, said: “In this study, we wanted to understand the mechanisms of creating ABC cells in the immune system, as well as find out whether these cells are good or bad for us when it comes to fighting infection. Although "ABC cells contribute to chronic inflammatory and autoimmune diseases, but we have discovered a previously unknown ability of these cells to fight disease."

He added, explaining: “Our research found that ABCs also have an effective role in the development of helper T cells, which generate powerful antibodies that help the body fight malaria parasites.”

Using gene editing technology in mice, the researchers discovered that a gene called Zeb2 is necessary for the production of ABCs.

Professor Ian Cockburn, co-author of the study, said: “We found that manipulating the Zeb2 gene disrupts the formation of ABCs in the immune system. We found that mice without the Zeb2 gene were unable to control malaria infection. Therefore, the results show that ABCs play a crucial role.” in combating malaria infection.

It is noteworthy that malaria killed more than 600,000 people around the world in 2022. Researchers face an uphill battle to find long-term treatments, as malaria parasites continue to find new ways to gain resistance to current treatments.

The research was published in the Journal of Immunology.
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