AstraZeneca and Johnson & Johnson vaccine, long-term efficacy

With adenoviral vector vaccines – such as AstraZeneca and Johnson & Johnson – “robust and long-term immune system responses” against coronavirus can be generated. This is what emerges from a work conducted by scientists from the University of Oxford (Gb) – a university that has also developed the AstraZeneca anti-Covid vaccine – and from the Cantonal Hospital of St. Gallen in Switzerland. Under the lens of the experts who sign a study published in ‘Nature Immunology’ the vectors of the adenovirus vaccine, such as the ChAdOx1 nCov-19 (AstraZeneca) construct. The authors describe one of the key characteristics of these vaccines: their ability to generate “strong and sustained populations of the ‘killer’ element of the immune system’s T cells”. In an animal model, scientists observed that adenoviruses are able to enter long-lived tissue cells, known as fibroblastic reticular cells, which in turn form small, well-organized clusters, serving as a ‘training ground’ for T cells. This mechanism appears to explain, the study authors note, how these vaccines achieve these robust immune system responses. “Millions of people will have received adenoviral vaccines worldwide, not just the Oxford-AstraZeneca vaccine, but the J&J vaccine. and also the Chinese and Russian versions. The ultimate goal of these vaccines is to induce long-term protection of the immune system using both antibodies and T cells, “notes Paul Klenerman, University of Oxford, one of the lead authors of the paper . Adenovirus vectors can target specific cells, known as stromal cells, in tissues such as the lung, generating ‘deposits’ of antigens in these long-lived cells. Their long-lived nature implies that the antigen can be ‘shown’ to the immune system many times, effectively enhancing the response. Experts also delved into other mechanisms that could explain the lasting efficacy, including the key chemical messenger involved in signaling to cells. T (IL-33, a so-called ‘alarmin’ released when stromal cells receive signals of distress). Regarding the observed endowment for adenoviral vector vaccines, the hope of the researchers is now “to be able to exploit it in the design of new vaccines, vaccines that we still desperately need for diseases such as tuberculosis, HIV, hepatitis C and cancer “, concludes Burkhard Ludewig, professor at the University of Zurich and head of the Medical Research Center, Cantonal Hospital of St. Gallen, lead author of the article.