Vaccination in cases of immunosuppression/chronic illness

Immunodeficiency characterises the condition of a person whose immune system is failing. It is the result of congenital disorders (primary immunodeficiency) or acquired disorders (such as HIV infection) or treatment (corticosteroid therapy or immunosuppressive treatments).

Vaccination in immunocompromised or asplenic individuals

Immunocompromised or asplenic individuals are particularly vulnerable to severe infections, which are often responsible for high morbidity and mortality rates. Vaccination in this context has major specificities that justify adapted recommendations:

Contraindication of live attenuated vaccines

Due to the risk of vaccine-associated disease, these vaccines are generally prohibited. However, their use may be considered on a case-by-case basis, after a rigorous assessment of the benefit-risk ratio, taking into account the danger associated with the infectious disease targeted.

Reduced vaccine immunogenicity

As the immune response is often attenuated, specific schedules may be necessary:

• Additional doses or closely spaced boosters
• Serological monitoring to ensure induced protection

Increased risk of certain infections

This implies prioritising specific vaccinations, particularly against:

• Pneumococcus, meningococcus, Haemophilus influenzae type b
• Seasonal influenza, COVID-19
• Hepatitis B (depending on individual risk factors)

Immune deficiencies fall into two main categories: hereditary (congenital) (agammaglobulinaemia, complement deficiency, lymphocyte deficiency) and secondary or acquired (HIV, transplantation, chemotherapy, immunosuppressive treatments). These deficiencies can affect humoral immunity (antibodies) and/or cellular immunity (T lymphocytes), depending on the clinical situation. Assessing these deficiencies is essential in order to adapt the vaccination strategy appropriately.

Apart from HIV infection, data on the efficacy, tolerance and impact of vaccines in immunocompromised individuals remain scarce. The lack of specific studies often leads to recommendations being based on expert consensus and theoretical reasoning.

The protection of immunocompromised individuals also depends on the protection of their immediate environment. Vaccinating family members, loved ones and caregivers limits the transmission of infectious agents by creating an indirect barrier.