Burden of COVID-19 disease and vaccine coverages in Apulian splenectomized patients: A retrospective observational study.

Splenectomy/asplenia is a condition associated with immune-compromission and specific vaccines are recommended for these patients, including the anti-COVID-19 vaccine. Among the high-risk group for which vaccination was prioritized in Italy, the immunocompromised patients after therapies or treatments were included. The Apulian regional archive of hospital discharge forms was used to define the list of splenectomized Apulian inhabitants, considering data from 2015 through 2020. The overall vaccination status of asplenic patients was assessed via data collected from the Regional Immunization Database. The history of SARS-CoV-2 infection and the infectious disease outcomes were extracted from the Italian Institute of Health platform "Integrated surveillance of COVID-19 cases in Italy". 1219 Apulian splenectomized inhabitants were included; the incidence rate of SARS-CoV-2 infection was 15.0 per 100 persons-year with a proportion of re-infection equal to 6.4%; the proportion of hospitalization was 2.9%, with a case-fatality rate of 2.6%. The vaccine coverage (VC) for the anti-COVID-19 vaccine basal routine was 64.2%, for the first booster dose was 15.4%, and for the second booster dose was 0.6%. A multifactorial approach is needed to increase the vaccination uptake in this sub-group population and to increase the awareness of the asplenia-related risks to patients and health personnel.