{"entity":{"id":"rejuv-frontier-immune-reconstitution","kind":"technology","name":"Rebuilding the immune system after treatment","aka":[],"tldr":"Chemotherapy, a transplant and CAR-T empty out the immune system, and rebuilding it takes months to years. Blood counts come back before protection does: the antibodies built up over a lifetime, from childhood jabs and from infections, are largely lost after a transplant. Re-vaccination puts them back, on a published schedule.","summary":"The immune system rebuilds in two ways, and they are not equally available to everyone. The surviving cells copy themselves, which is fast; and the thymus makes new ones that have never met anything, which is slow and declines with age, though measurement of T-cell receptor excision circles shows some output continues into late adulthood. An adult therefore rebuilds mostly by copying what survived, which is why the range of things the immune system can recognise stays narrower than it was even once the blood counts look normal.\n\nAfter allogeneic transplant the loss is explicit. The ECIL-7 guideline states that most recipients lose their immunity to various pathogens within the first months after transplant regardless of pre-transplant vaccination of donor or recipient, that responses to vaccines are lower than in healthy people of the same age for the first months or years and improve to near normal two to three years after the procedure, and that inactivated vaccines should be started from three months after transplant whether or not graft-versus-host disease has developed or immunosuppressants are being given. Live attenuated vaccines are restricted to specific situations. The UK Green Book says the same in fewer words: protective antibodies from before transplant are likely to be lost, it is unclear whether the recipient acquires the donor's immunity, and all such people should be considered for a re-immunisation programme. The IDSA guideline covers the wider immunocompromised population.\n\nAfter CAR-T the picture is B-cell rather than T-cell. In 133 patients treated with CD19-directed CAR-T, 30 (23 per cent) had an infection within 28 days, 6 (5 per cent) an invasive fungal infection and 5 (4 per cent) a life-threatening or fatal infection; the infection rate fell after day 28. On-target B-cell aplasia removes the cells that make antibody, so immunoglobulin replacement and continued vigilance are part of follow-up. After conventional chemotherapy without transplant, recovery is usually faster but revaccination still needs to be timed against the treatment, which is what the guidelines are for.\n\nNothing here is sold by a clinic and nothing here costs much. Ask the treating team for a written revaccination plan; if there is not one, that is the gap to close before anything else on this page is worth considering.","status":"standard-of-care","asOf":"2026-10-02","wikipedia":"https://en.wikipedia.org/wiki/Immunosenescence","links":[{"label":"Cordonnier et al., Vaccination of haemopoietic stem cell transplant recipients: guidelines of the 2017 European Conference on Infections in Leukaemia (ECIL 7) (Lancet Infect Dis 2019)","url":"https://doi.org/10.1016/S1473-3099(18)30600-5"},{"label":"Rubin et al., 2013 IDSA clinical practice guideline for vaccination of the immunocompromised host (Clin Infect Dis 2014)","url":"https://doi.org/10.1093/cid/cit684"},{"label":"UK Green Book chapter 7: immunisation of individuals with underlying medical conditions (January 2020)","url":"https://www.gov.uk/government/publications/immunisation-of-individuals-with-underlying-medical-conditions-the-green-book-chapter-7"},{"label":"Hill et al., Infectious complications of CD19-targeted chimeric antigen receptor-modified T-cell immunotherapy (Blood 2018)","url":"https://doi.org/10.1182/blood-2017-07-793760"},{"label":"Douek et al., Changes in thymic function with age and during the treatment of HIV infection (Nature 1998)","url":"https://doi.org/10.1038/25374"}],"tags":["rejuvenation","survivorship","evidence:strong","infection","vaccination"],"related":[],"cancers":[],"sections":["rejuvenation","supportive-care"],"technologies":["allogeneic-hsct","autologous-stem-cell-transplant","car-t","survivorship-care-plan"],"targets":[],"drugs":["rituximab"],"companies":[],"institutions":[],"pathways":[],"terms":["late-effects"],"trials":[],"people":[],"bottlenecks":["b-survivorship","b-toxicity-qol"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"principle":"Cytotoxic therapy and conditioning deplete lymphocytes; recovery proceeds by peripheral expansion of surviving clones first and by thymic production of new naive cells later and more slowly. B-cell-directed therapy additionally removes the plasma-cell precursors that carry serological memory, so antibody titres fall even when cell counts return.","strengths":["Guidelines from ECIL, IDSA and the UK Green Book cover the schedules","Vaccination with inactivated vaccines after transplant is safe and effective","Free at the point of use in the NHS and covered by most systems","The deficit is measurable, so follow-up can be targeted"],"limitations":["Response to vaccines is lower for the first months to years after transplant","Live attenuated vaccines are restricted and need specialist judgement","Revaccination after conventional chemotherapy is less standardised than after transplant","Nothing restores a repertoire to exactly what it was"]},"route":"/technologies/rejuv-frontier-immune-reconstitution/","neighbours":{"section":[{"id":"rejuvenation","kind":"section","name":"Recovery & Rejuvenation","route":"/fronts/rejuvenation/"},{"id":"supportive-care","kind":"section","name":"Supportive Care & Survivorship","route":"/fronts/supportive-care/"}],"technology":[{"id":"rejuv-tx-what-to-ask-for","kind":"technology","name":"After a transplant or cell therapy: what to ask for","route":"/technologies/rejuv-tx-what-to-ask-for/"},{"id":"allogeneic-hsct","kind":"technology","name":"Allogeneic stem cell transplantation","route":"/technologies/allogeneic-hsct/"},{"id":"autologous-stem-cell-transplant","kind":"technology","name":"Autologous stem cell transplant (high-dose therapy)","route":"/technologies/autologous-stem-cell-transplant/"},{"id":"car-t","kind":"technology","name":"CAR-T cell therapy","route":"/technologies/car-t/"},{"id":"rejuv-frontier-rapamycin-ageing","kind":"technology","name":"Rapamycin and mTOR inhibition for ageing","route":"/technologies/rejuv-frontier-rapamycin-ageing/"},{"id":"rejuv-tx-immune-reconstitution-timeline","kind":"technology","name":"Rebuilding an immune system: the timeline, lineage by lineage","route":"/technologies/rejuv-tx-immune-reconstitution-timeline/"},{"id":"rejuv-tx-revaccination","kind":"technology","name":"Revaccination after transplant: the schedules, and where the UK and the US differ","route":"/technologies/rejuv-tx-revaccination/"},{"id":"survivorship-care-plan","kind":"technology","name":"Survivorship care and late-effects surveillance","route":"/technologies/survivorship-care-plan/"},{"id":"rejuv-frontier-what-works","kind":"technology","name":"What actually works after treatment","route":"/technologies/rejuv-frontier-what-works/"}],"drug":[{"id":"rituximab","kind":"drug","name":"Rituximab","route":"/drugs/rituximab/"}],"term":[{"id":"late-effects","kind":"term","name":"Late effects and survivorship toxicity","route":"/terms/late-effects/"}],"bottleneck":[{"id":"b-survivorship","kind":"bottleneck","name":"Survivorship and late effects are neglected","route":"/bottlenecks/b-survivorship/"},{"id":"b-toxicity-qol","kind":"bottleneck","name":"Toxicity and quality of life are undervalued","route":"/bottlenecks/b-toxicity-qol/"}]}}