Immunization coverage among asplenic patients and strategies to increase vaccination compliance: a systematic review and meta-analysis

Background: Asplenic or splenectomized patients have a higher risk (ranging from 10 to 50-fold) than the general population of developing an overwhelming post-splenectomy infection (OPSI). Thus, they should receive specific vaccinations to prevent bacterial infections and influenza. The aim of this meta-analysis was to estimate vaccination coverage (VC) with the recommended vaccines among splenectomized patients; strategies recommended in those studies to improve VC worldwide are considered as well. Research design and methods: Scopus, MEDLINE/PubMed, Google Scholar and ISI Web of Knowledge databases were searched. Research papers, short reports, reviews, and meta-analyses published between January 1, 2010 and July 18, 2020 were included; no geographic restrictions were included. Twenty-four studies were included in the meta-analysis. Results: For anti-pneumococcal vaccination, coverage was 55.1% (95%CI = 41.0–69.2%), for anti-Hib 48.3% (95%CI = 34.3–52.3%), for anti-meningococcal C/ACYW135 33.7% (95%CI = 23.6–43.9%), for anti-meningococcal B 13.3% (95%CI = 7.0–19.5%) and for anti-influenza 53.2% (95%CI = 22.0–84.4%). Most studies determined a lack of adherence to international guidelines by healthcare workers and suggested the need to better educate health professionals in the management of post-splenectomy patients. Conclusions: The meta-analysis showed the suboptimal immunization coverage for the vaccines recommended for asplenic patients. Greater efforts must be made by public health professionals to increase VC in this group of patients at risk. Introducing specific prophylaxis protocols in the clinical routine seems to guarantee better immunization compliance in those patients.