Moreover, studies of mainly adults have shown that PCV7 is immunogenic in patients with leukemia, especially if it

is administered at an early stage of the disease (i.e. before the start of chemotherapy and the development of hypogammaglobulinemia) [54] and [55]. None of these few studies reported any safety or tolerability problems [53], [54] and [55]. Although meningococcal vaccine is recommended by health authorities for all high-risk subjects, buy SCH772984 there are very few studies of its use in children with cancer receiving standard chemotherapy [24] and [56]. One of the main study was performed by Yu et al., who administered meningococcal C CRM197 conjugate vaccine to 35 children aged 2.1–17.8 years, most of whom had ALL [56]. The children were on maintenance therapy or had completed chemotherapy between three and 18 months earlier. Fifty percent of the children showed a positive serological response, defined as a four-fold increase in meningococcal-specific

IgG, and a complement-mediated bactericidal response was demonstrated in 44%; however, only 39% of children showed a simultaneous serological GSI-IX and bactericidal response. The response was strictly related to total B cell counts and the proximity of chemotherapy. The vaccine was safe and well tolerated by all of the children [56]. Children with cancer are considered to be at risk of influenza-related complications because they often require intensive care and prolonged hospitalisation during the course all of influenza, and influenza can considerably

delay the start of chemotherapy drug administration [57], [58] and [59]. A number of studies investigating the use of trivalent influenza vaccine in children with ALL and solid tumours have been carried out, but most of them were published some years ago, and only a few have made use of newer vaccines [60], [61], [62], [63], [64], [65], [66], [67], [68] and [69]. Furthermore, although all of these studies evaluated immunity, safety and tolerability, there are no published data concerning vaccine efficacy in laboratory-confirmed cases, hospitalisation, chemotherapy delays or mortality. Nevertheless a global evaluation indicates that inactivated influenza vaccines are safe and well tolerated: no serious adverse events have been observed and the proportion of mild adverse events is no different from that observed in healthy subjects [60], [61], [62], [63], [64], [65], [66], [67], [68] and [69]. Children with cancer seem to be able to generate a sufficient immune response to the influenza antigens contained in the vaccines when receiving chemotherapy, but this response is weaker than that of healthy children or children with cancer who have discontinued chemotherapy for more than 1 month (both groups show similar antibody production) [61], [62], [63] and [64].