title: Immunogenicity and safety of intradermal influenza vaccine in immunocompromized patients: a meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  The primary influenza prevention strategy is focused on annual vaccination according to the categories identified in the various countries as being at greatest risk of complications. Many studies were conducted in order to demonstrate that intradermal (ID) vaccine formulation represents a promising alternative to conventional intramuscular (IM) formulation, especially in subjects with an impaired immune system. However, there is no consensus whether the efficacy and safety of ID is equivalent to IM in these subjects. Therefore, we performed a meta-analysis of Randomized Controlled Trials (RCT) to compare the immunogenicity and safety of ID and IM influenza vaccines in subjects with a depleted immune system.
  
  
  METHODS
  We conducted a search strategy of medical literature published until November 2014 in order to identify RCTs that evaluated the immunogenicity and safety of ID compared with IM influenza vaccines in immunocompromized patients.
  
  
  RESULTS
  We identified a total of 269 citations through research in electronic databases and scanning reference lists. Of these, 6 articles were included in the meta-analysis, for a total of 673 subjects. The seroprotection rate induced by the ID vaccine is comparable to that elicited by the IM vaccine. The overall RR was 1.00 (95 % CI = 0.91 -1.10) for A/H1N1 strain, 1.00 (95 % CI = 0.90-1.12) for A/H3N2 and 0.99 (95 % CI = 0.84 -1.16) for B strain. No significant differences in the occurrence of systemic reactions were detected (17.7 % in the ID group vs 18.2 % in the IM group) with a pooled RR = 1.00 (95 % CI = 0.67 -1.51), whereas ID administration caused significantly more injection site reactions with a mean frequency of 46 % in the ID group compared to 22 % in the IM group, with a pooled RR = 1.89 (95 % CI = 1.40 -2.57).
  
  
  CONCLUSIONS
  The ID influenza vaccine has shown a similar immunogenicity and safety to the IM influenza vaccine in immunocompromized patients, and it may be a valid option to increase compliance to influenza vaccination in these populations.
authors.affiliation: Department of Health Sciences, University of Catanzaro "Magna Græcia", Via Tommaso Campanella, 88100, Catanzaro, Italy. claudiapileggi@unicz.it.
authors.forename: Claudia
authors.initials: C
authors.lastname: Pileggi
authors.affiliation: Department of Health Sciences, University of Catanzaro "Magna Græcia", Via Tommaso Campanella, 88100, Catanzaro, Italy. francescalotito@libero.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Lotito
authors.affiliation: Department of Health Sciences, University of Catanzaro "Magna Græcia", Via Tommaso Campanella, 88100, Catanzaro, Italy. a.bianco@unicz.it.
authors.forename: Aida
authors.initials: A
authors.lastname: Bianco
authors.affiliation: Department of Health Sciences, University of Catanzaro "Magna Græcia", Via Tommaso Campanella, 88100, Catanzaro, Italy. nobile@unicz.it.
authors.forename: Carmelo G A
authors.initials: CG
authors.lastname: Nobile
authors.affiliation: Department of Health Sciences, University of Catanzaro "Magna Græcia", Via Tommaso Campanella, 88100, Catanzaro, Italy. pavia@unicz.it.
authors.forename: Maria
authors.initials: M
authors.lastname: Pavia
mesh_terms: D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D000917:Antibody Formation; D016208:Databases, Factual; D006801:Humans; D016867:Immunocompromised Host; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000517:prevention & control*; D007273:Injections, Intramuscular; D016032:Randomized Controlled Trials as Topic
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines