Review article Influence of anesthesia on immune responses and its effect on vaccination in children: review of evidence J.N. SIEBERT MD MD *, K.M. POSFAY-BARBE MD, MS MD, MS †, W. HABRE MD, P MD, PhD à AND C.-A. SIEGRIST MD MD * *World Health Organization Collaborating Center for Neonatal Vaccinology, Departments of Pathology and Pediatrics, University of Geneva Medical School, †Department of Pediatrics, Geneva Children’s Hospital, University Hospitals of Geneva and àDepartment of Anesthesiology, Geneva Children’s Hospital, University Hospitals of Geneva, Geneva, Switzerland Summary Anesthesia and surgery exert immunomodulatory effects and some authors argue that they may exert additive or synergistic influences on vaccine efficacy and safety. Alternatively, inflammatory responses and fever elicited by vaccines may interfere with the postoperative course. There is a lack of consensus approach among anesthesiologists to the theoretical risk of anesthesia and vaccination. Few studies have assessed the influence of anesthesia and surgery on pediatric vaccine responses. We have undertaken an extensive review of articles published in English between 1970 and 2006 meeting the criteria: measurement of immune parameters following general anesthesia in children. By searching the major medical databases (OVID Medline, PubMed, ISI Web of Science) and references cited in the articles themselves, among 277 articles obtained none examined directly the influence of anesthesia/surgery on vaccine responses. Only 16 original reports assessed the influence of several anesthetic agents on various markers of immunity including lymphocyte numbers and functions. These results are reinterpreted here in view of our current under- standing of the immune mechanisms underlying vaccine efficacy and adverse events. We conclude that the immunomodulatory influence of anesthesia during elective surgery is both minor and transient (around 48 h) and that the current evidence does not provide any contraindication to the immunization of healthy children scheduled for elective surgery. However, respecting a minimal delay of 2 days (inactivated vaccines) or 14–21 days (live attenuated viral vaccines) between immunization and anesthesia may be useful to avoid the risk of misinterpretation of vaccine-driven adverse events as postoperative complications. Correspondence to: Prof. Claire-Anne Siegrist, World Health Organization Collaborating Center for Neonatal Vaccinology, Depart- ments of Pathology and Pediatrics, University of Geneva Medical School, 1, Rue Michel-Servet, CH-1211, Geneva, Switzerland (email: claire-anne.siegrist@medecine.unige.ch). Pediatric Anesthesia 2007 17: 410–420 doi:10.1111/j.1460-9592.2006.02120.x Ó 2006 The Authors 410 Journal compilation Ó 2007 Blackwell Publishing Ltd