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Immunity and infection prevention

Immune memory

The main article (“Immune memory”) explains how immune memory forms. This topic shows what happens to that memory after leukaemia treatment and how it is rebuilt.

Last updated: ~1 min read
A library of cells with empty shelves.
Figure 1.After treatment, part of the memory can be lost.

01Short answer

Memory B and T cells live for years and quickly recognise a familiar microbe. Intensive chemotherapy, anti-CD20 antibodies, CAR-T and especially allogeneic transplant can destroy some or all of these cells. As a result, protection from childhood vaccines can weaken. That is why a re-vaccination schedule “from scratch” is usually drawn up after a transplant, and after other treatments your doctor assesses which vaccines need repeating. Live vaccines are only possible once immunity has recovered enough.

02Simple explanation

Memory can be lost, especially after a transplant.

Re-vaccination rebuilds memory.

Live vaccines: only with approval.

03Scientific explanation

Transplant: after an allogeneic transplant, the immune system is rebuilt from donor cells, so international guidance advises repeating vaccines.

Timing: the vaccine response depends on B-cell recovery; a vaccine given too early may give a weak response.

04What happens in the body?

A memory library

Every vaccine and past infection is like a “book”. Strong treatment can empty the shelves.

Refilling the shelves

Re-vaccination adds new books, step by step over months and years.

Shelves filling with new books of light.
Figure 2.Vaccines refill the shelves.

The schedule

The transplant or haematology team decides which vaccine is given when.

A blank vaccine card and a calendar.
Figure 3.A re-vaccination schedule.

05Rebuilding memory

Four steps.

Loss — Memory weakens.1LossMemory weakens.
Check — Readiness is assessed.2CheckReadiness is assessed.
Vaccine — A new “lesson”.3VaccineA new “lesson”.
Protection — Memory is restored.4ProtectionMemory is restored.

06Treatment and immune memory

TreatmentEffect on memory (general)
Standard chemotherapyPartial weakening possible
Anti-CD20 antibodiesB-cell memory weakened for months
CAR-T (B-cell)B cells may stay low for a long time
Allogeneic transplantVaccines are usually repeated

07Key terms

Memory cell
A lymphocyte that “remembers” a microbe.
Re-vaccination
Giving vaccines again.
Live vaccine
A vaccine with a weakened live microbe.
B-cell recovery
The return of antibody-making cells.
Vaccine response
The protection produced by a vaccine.

08Key points

  • Strong treatment can weaken immune memory.
  • Vaccines are usually repeated after a transplant.
  • Your team chooses the timing.
  • Live vaccines only with approval.
  • Family members’ vaccines protect you too.
  • Keep your vaccination card.

09Frequently asked questions

Do my childhood vaccines no longer protect me?

Sometimes protection weakens; if needed, your doctor will offer an antibody test or re-vaccination.

When do we start?

Usually months after treatment or transplant; the schedule is individual.

What about the flu vaccine?

The inactivated flu vaccine is often advised earlier; ask your team.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Do my childhood vaccines no longer protect me?

  2. When do we start?

  3. What about the flu vaccine?

My questions

12Sources

  1. MedlinePlus (U.S. National Library of Medicine). Immune response
  2. MedlinePlus (U.S. National Library of Medicine). Immunization
  3. World Health Organization (WHO). Vaccines and immunization
  4. National Cancer Institute (NCI). Infection and Neutropenia during Cancer Treatment
  5. American Cancer Society. Chronic Lymphocytic Leukemia Stages
  6. World Health Organization (WHO). Sepsis — fact sheet
  7. Macmillan Cancer Support. Infection
  8. World Health Organization (WHO). World Hand Hygiene Day
  9. Centers for Disease Control and Prevention (CDC). Preventing Infections in Cancer Patients
  10. American Cancer Society. Preventing Infections in People with Cancer
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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