Influenza immunization in immunosuppressed children. Response to influenza vaccine in children with leukemia undergoing chemotherapy. Influenza immunization of children with neoplastic diseases. Immune responses to influenza immunization in children receiving maintenance chemotherapy for acute lymphoblastic leukemia. Influenza immunisation in children with solid tumours. Immune response after influenza vaccination in children with cancer. Response to influenza immunisation during treatment for cancer. Antibody responses to influenza immunization of children with acute lymphoblastic leukemia.
Optimal influenza immunization of individuals with malignancy and other immunodeficient states requires and understanding of responses to currently recommended regimens. Children with acute lymphocytic leukemia and other malignancies between three and 17 years of age were immunized with bivalent influenza vaccine containing A/New Jersey/76 and A/Victoria/75. Folowing a two-dose immunization schedule, only 37% (25468) on cancer chemotherapy seroconverted to a hemagglutination inhibition titer greater than or equal to 20 for A/NJ/76; the seroconversion rate in those not on chemotherapy was 92% (68/74, P less than 0.001). The immune response to the A/Vic/75 antigen was also related to a history of recent chemotherapy. There was no correlation between the immune response and the peripheral white blood cell count except at counts less than or equal to 1,000. The optimum time to immunize children with malignancies is when they have been off chemotherapy for one month and have peripheral white blood counts greater than 1,000. To assess the ability of children with acute lymphoblastic leukemia (ALL) to develop an antibody response after influenza vaccination.
                A total of 65 children under 15 years old were studied, including 25 children with ALL undergoing chemotherapy, 30 with asthma in remission who were regularly followed at clinics, and 10 healthy children. The influenza vaccine contained antigens B/Yamanashi/166/98, A/New Caledonia/20/99 (H1N1), and A/Panama/2007/99 (H3N2).
                Children with ALL developed significant antibody titers to A/Panama /2007/ 99 antigen 4 weeks after the second immunization. Seroconversion rates after two doses of vaccine were 57.1 to 84.6% and seroresponse rates were between 24 and 60% in children with ALL. Compared to children with asthma in remission, who were regarded as immunocompetent individuals, the ALL children had less seroconversion and lower seroresponse rates to A/New Caledonia/20/99 (H1N1). The seroconversion and seroresponse rates to B/Yamanashi/166/98 and A/ Panama/2007/99(H3N2) antigens were comparable in asthmatic and leukemic children. On the other hand, the antibody response in children with ALL who received reinduction chemotherapy suggests that the therapy did not impair seroresponse rates.
                Our data suggest that the influenza vaccine is safe and effective in children with either ALL or asthma in Taiwan. During the National Influenza Immunization Program in 1976, 147 children with neoplastic diseases received Wyeth split-product bivalent influenza vaccine: A/New Jersey/8/76 (HSW1N1), A/Victoria/3/75 (H3N2). Thirteen normal siblings served as controls. Seventy-one patients received two doses of the vaccine four weeks apart. After the second injection of A/NJ/8/76, there was a difference between the response of the patients on chemotherapy and those off therapy greater than or equal to 30 days--38% vs. 76%, P less than 0.01 for four-fold rise and 26% vs. 57%, P less than 0.05 for the attainment of protective (greater than or equal to 32) hemagglutination inhibition (HI) titers. These differences were observed in both leukemia-lymphoma and solid tumor patients. There was a difference in HI titers to A/Vic/75 between patients on and off chemotherapy after a single injection, 34% vs. 71%, P less than 0.001 for a four-fold rise. After the second immunization, only 52% on, and 86% off therapy (P less than 0.05) had a four-fold rise in titers. Thirty-two percent of the patients on treatment who achieved "protective" titers did so only after the second immunization. Immunoglobulin levels and neutropenia did not correlate with the inability to obtain a four-fold rise in titers. Our findings suggest that patients on chemotherapy cannot be effectively vaccinated by a new antigen, and that single yearly boosters may be insufficient for recall of old antigens. Patients off chemotherapy greater than or equal to 30 days respond as normal controls. To compare the immune responses to influenza vaccine in children with acute lymphoblastic leukemia (ALL) receiving maintenance chemotherapy with those in healthy children.
                Hemagglutinin-inhibition (HAI) antibody titers were determined before and after influenza vaccination in children with ALL and healthy controls. Immune responses were measured as geometric mean titers (GMT) and 4-fold rises in HAI titers.
                Although post-immunization GMT were lower in children with ALL compared to healthy children for the H1N1 antigen (P<0.001), the H3N2 antigen (P=0.03), and for the influenza B antigen (P=0.003), at least 60% of children with ALL had at least a 4-fold rise in HAI titers to each of the influenza antigens.
                While the GMT after trivalent influenza immunization in children with ALL were significantly lower than those seen in healthy children, the majority of children with ALL had 4-fold rises in HAI titers. Children receiving maintenance chemotherapy for ALL should receive yearly influenza vaccine.
                Copyright 2003 Wiley-Liss, Inc. We assessed response to immunisation with trivalent split virus influenza vaccine in children with non-leukaemic malignant disease. Children with solid tumours and lymphoma received one or two doses of influenza vaccine, according to current UK guidelines, in autumn 2001 and/or 2002. Children were currently receiving chemotherapy or were within 6 months of completing chemotherapy. Pre and post vaccination sera were assessed for antibodies to the prevalent influenza strains by haemagglutination inhibition (HI). Sixty six children were assessed prior to 69 episodes of vaccination. In 30% episodes, children were susceptible to all three circulating influenza viruses (65% to H1N1, 42% to H3N2 and 90% to B) and only one patient showed protective titres (HI32) against all three strains. Seroresponse rates (4-fold rise in HI) for H1N1, H3N2 and B were 52%, 33% and 51% in 65 episodes. Following immunisation protective titres to all three viruses were seen in 25 episodes (38%) and protective responses to one or two viruses were seen in a further 12 (19%) episodes. There was no significant difference in response rates among children on treatment and off treatment and by intensity of chemotherapy. Children with solid tumours and lymphoma are highly susceptible to influenza infection. Influenza vaccine was well tolerated in this patient group and children showed a significant response to immunisation. These findings support the recommendation for annual influenza vaccination in these children. To assess the immune response to inactivated trivalent split influenza vaccine in children with cancer.
                Forty-four children with various types of malignancies received two doses of influenza vaccine 2-4 weeks apart. Hemagglutinin-inhibition (HI) antibody titers were determined in paired sera obtained just before the first vaccination and 4 weeks after the second vaccination.
                Influenza vaccine was administered to all children without any serious adverse effects. Protective titer rates (proportion of patients achieving antibody titers > or =40 among those with pre-vaccination titers <40) and response rates (proportion of patients with fourfold or more antibody rise) were 72% and 65% for H1N1, 60% and 40% for H3N2, and 38% and 46% for influenza B, respectively. However, patients on chemotherapy showed a significantly lower immune response to influenza A than those having completed chemotherapy; protection titer rates were 42% versus 90% for H1N1 (P = 0.006) and 25% versus 83% for H3N2 (P = 0.019). For influenza B, patients with low IgG showed a lower response rate than those with high IgG (29% vs. 61%, P = 0.040). Multivariate analysis revealed that factors significantly associated with a lower immune response were low IgG (P < 0.001) and administration of chemotherapy (P = 0.003) for H1N1, administration of chemotherapy (P = 0.008) for H3N2, and low white blood cell (WBC) count (P = 0.030) and low IgG (P = 0.030) for influenza B.
                Influenza vaccination given to children with cancer was safe and induced immune reaction comparable to healthy children, although patients on chemotherapy and/or with chemotherapy-related conditions had a limited ability to produce a sufficient immune response.
                (c) 2005 Wiley-Liss, Inc. To assess the annual risk of influenza infection in children with cancer and the immunogenicity of a trivalent split virus influenza vaccine in these children.
                Eighty four children with cancer were tested for susceptibility to the circulating strains of influenza virus in autumn 1995 and 1996. Non-immunised children were reassessed the following spring for serological evidence of natural infection. Forty two patients received two doses of influenza vaccine. These children were receiving continuing chemotherapy for acute lymphoblastic leukaemia or were within six months of completing chemotherapy.
                Among the 84 children tested for influenza virus susceptibility only 8% of patients were fully protected (antibody titres >/= 40) against all three of the prevalent influenza virus strains; 33% were susceptible to all three viruses. Evidence of acquired natural infection was seen in 30% of unimmunised patients. Among immunised susceptible patients, 66% made some protective response to the vaccine and 55% showed protective antibody titres to all three viral strains following vaccination. Older age was associated with increased response to the H1N1 and H3N2 vaccine components, but total white cell count or neutrophil count at immunisation, type of cancer, or length of time on treatment for acute lymphoblastic leukaemia did not affect response.
                Most children with cancer studied were at risk of influenza infection. A significant response to immunisation was seen, supporting annual influenza vaccination for children being treated for cancer. Antibody responses of two doses of a bivalent influenza vaccine containing A/Victoria/75 (A/Vic/75) and A/New Jersey/76 (A/NJ/76) viral antigens were studied in 22 children receiving maintenance chemotherapy for acute lymphoblastic leukemia (ALL), 16 children no longer receiving therapy for ALL, and 50 sibling controls. Before immunization, the three groups showed no difference in titer of antibody to either antigen. After the first immunization, children off therapy showed significantly higher titers to A/NJ/76 than did either sibling controls of children receiving therapy (P less than 0.01). After the second immunization, children off therapy showed significantly higher antibody titers to both antigens than did children receiving therapy or controls (P less than 0.01 for both A/NJ/76 and A/Vic/75). Antibody titers of children receiving therapy were not significantly different from those of controls. A year later, there were no significant differences in antibody titers among the groups. Thus, children with ALL who are receiving chemotherapy respond normally to two doses of influenza vaccine, whereas children off therapy manifest abnormally high titers of antibody to both influenza virus antigens.