COSMOS MAGAZINE
A study from Australian researchers suggests that receiving a COVID-19 vaccine and its booster in the same arm leads to a faster and more robust immune response.
Memory B cells (red) interacting with macrophages (white) inside a lymph node (blue). Credit: Rama Dhenni
The effect appears to stem from the lymph node nearest the injection site, where
immune memory and response are most strongly activated.
In both animal studies and a human trial of 30 participants, those who had both shots in the same arm developed virus-neutralising antibodies more quickly — within a week of the second dose.
Early immune protection was also found to be more effective against variants like Delta and Omicron, though antibody levels eventually equalised between both groups after four weeks.
Researchers say the findings could help optimise future vaccination strategies and support the design of next-generation vaccines that work faster and require fewer boosters.