Understanding booster vaccines

Researchers in France have used ‘organ-on-chip’ technology to shed light on the effectiveness of booster vaccines for Covid-19 and other infectious diseases.

Booster vaccines can be given as an additional shot after initial vaccination to increase immunity, which may be necessary when protection wears off over time, or when a virus mutates, making the vaccine less effective.

The study at the Pasteur Institute, Paris, created an artificial version of the lymph nodes and spleen, which co-ordinate the body’s immune response to a vaccine, by embedding human blood cells on microfluidic chips – a so-called organ-on-a-chip system.

When the system was exposed to proteins from different viruses, such as the spike protein of SARS-CoV-2 that allows the virus to enter and infect cells, the team saw that immune cells (found in the blood) behaved in the same way as they do in the body, for example by producing antibodies against the virus. The system could also respond to different types of vaccine.

By creating different versions of the organ-on-chip using blood samples from different donors, the researchers could also observe a range of immune responses that may help indicate how well someone reacts to a booster vaccine.

Lead researcher, Lisa Chakrabarti, said: “The Covid-19 pandemic has emphasised the need for preclinical systems that enable a rapid evaluation of immune responses elicited by candidate booster vaccines, particularly within specific cohorts of high-risk individuals.”