Abstract: Vaccine-preventable diseases and their related complications are  associated with increased morbidity and mortality in patients with  altered immunocompetence. Optimised immunisation in this patient  population is challenging because of limited data from vaccine trials,  suboptimal vaccine efficacy and safety concerns. Reliable efficacy data  are lacking among patients with altered immunocompetence, and existing  recommendations are mainly based on expert consensus and may vary  geographically. Inactivated vaccines can be generally used without risks  in this group, but their efficacy may be reduced, and immunisation  schedules vary according to local guidelines, age, and type and stage of  the underlying disease. Live vaccines, if indicated, should be  administered with care because of the risk of vaccine-associated  disease. We have reviewed the current evidence on vaccination principles  and recommendations in adult patients with secondary  immunodeficiencies, including asplenia, HIV infection, stem cell and  solid organ transplant, haematological malignancies, inflammatory bowel  disease and other chronic disorders.

Keywords: Altered immunocompetence; Inactivated vaccines; Live vaccines; Vaccination.