E delivery, gestational hypertension, and premature uterine contractions. The independent adjudication committee considered none of the events to berelated to the vaccine. No serious adverse events were reported in any neonate, and no maternal or Castanospermine infant deaths occurred.DiscussionIt is recommended that all women who will be TA-02 site pregnant during influenza season receive inactivated influenza vaccine at any point in gestation by The Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) and The American College of Obstetricians and Gynecologists’ Committee on Obstetric Practice [29]. However, published data of the maternal immunogenicity of influenza vaccines were mainly from the United States and Europe. To the best of our knowledge, ours is the first published trial to evaluate both maternal immune response and neonate seroprotection from a single dose of trivalent influenza vaccine 16574785 in pregnant women in Asia. In this prospective study, we demonstrated that pregnant women receiving the trivalent influenza vaccine produce antibodies sufficient to provide protection against influenza infection both in the mother and the newborn. An HAI antibody titer of 1:40 after vaccination is the current standard for licensure of influenza vaccines, and a widely accepted surrogate for protection against influenza infection [30]. In this study, women who were vaccinated had HAI GMTs above this threshold value at day 28 against H1N1, H3N2, and influenza B virus and at delivery against H1N1 and H3N2 virus, suggesting protection against these specific influenza strains. On the other hand, according to the Committee of Medicinal Products for Human Use (CHMP) guidance, at least 1 of 3 serological assessments (seroprotection, seroconversion, and an increase ratio of HAI titers) is necessary to meet the requirements for seasonal influenza vaccines. In this study, 28 days after vaccination the seroprotection and seroconversion rates and the increased ratio of HAI titers against influenza type A (H1N1 and H3N2) viruses and the seroconversion and the increase ratio in HAI titers against influenza type B were fully compliant with the CHMP criteria for seasonal influenza vaccines. These data support the clinical utility of the AdimFlu-SH vaccine. Vaccine administration to pregnant women has been used to protect infants against infection in the first few months of life. Here, we examined transplacental antibody transfer following influenza vaccination. The seroprotection rate of cord blood correlated to that of the maternal samples at delivery, consistent with a study by Sumaya and Gibbs [31]. Administration of the vaccine to pregnant women resulted in detectable antibodies against H1N1 and H3N2 virus in umbilical cord venous blood with GMTs .1:40, but no enough rise of antibodies against influenza B virus. This finding is consistent with previous studies of seasonal influenza vaccination [32,33]. The finding that GMT titers of influenza B virus were lower than those of H1N1 and H3N2 might be the result of poor sensitivity of the ELISA assay used for the detection of influenza B virus antigen. Our results showed that cord blood samples had higher mean HAI titers than the maternal samples at the time of delivery, a finding consistent with those of a previous trial in pregnant women [34]. In that study, a single dose of a monovalent 2009 H1N1 flu vaccine was administrated to pregnant women, and a high seroprotection rate was reported.E delivery, gestational hypertension, and premature uterine contractions. The independent adjudication committee considered none of the events to berelated to the vaccine. No serious adverse events were reported in any neonate, and no maternal or infant deaths occurred.DiscussionIt is recommended that all women who will be pregnant during influenza season receive inactivated influenza vaccine at any point in gestation by The Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) and The American College of Obstetricians and Gynecologists’ Committee on Obstetric Practice [29]. However, published data of the maternal immunogenicity of influenza vaccines were mainly from the United States and Europe. To the best of our knowledge, ours is the first published trial to evaluate both maternal immune response and neonate seroprotection from a single dose of trivalent influenza vaccine 16574785 in pregnant women in Asia. In this prospective study, we demonstrated that pregnant women receiving the trivalent influenza vaccine produce antibodies sufficient to provide protection against influenza infection both in the mother and the newborn. An HAI antibody titer of 1:40 after vaccination is the current standard for licensure of influenza vaccines, and a widely accepted surrogate for protection against influenza infection [30]. In this study, women who were vaccinated had HAI GMTs above this threshold value at day 28 against H1N1, H3N2, and influenza B virus and at delivery against H1N1 and H3N2 virus, suggesting protection against these specific influenza strains. On the other hand, according to the Committee of Medicinal Products for Human Use (CHMP) guidance, at least 1 of 3 serological assessments (seroprotection, seroconversion, and an increase ratio of HAI titers) is necessary to meet the requirements for seasonal influenza vaccines. In this study, 28 days after vaccination the seroprotection and seroconversion rates and the increased ratio of HAI titers against influenza type A (H1N1 and H3N2) viruses and the seroconversion and the increase ratio in HAI titers against influenza type B were fully compliant with the CHMP criteria for seasonal influenza vaccines. These data support the clinical utility of the AdimFlu-SH vaccine. Vaccine administration to pregnant women has been used to protect infants against infection in the first few months of life. Here, we examined transplacental antibody transfer following influenza vaccination. The seroprotection rate of cord blood correlated to that of the maternal samples at delivery, consistent with a study by Sumaya and Gibbs [31]. Administration of the vaccine to pregnant women resulted in detectable antibodies against H1N1 and H3N2 virus in umbilical cord venous blood with GMTs .1:40, but no enough rise of antibodies against influenza B virus. This finding is consistent with previous studies of seasonal influenza vaccination [32,33]. The finding that GMT titers of influenza B virus were lower than those of H1N1 and H3N2 might be the result of poor sensitivity of the ELISA assay used for the detection of influenza B virus antigen. Our results showed that cord blood samples had higher mean HAI titers than the maternal samples at the time of delivery, a finding consistent with those of a previous trial in pregnant women [34]. In that study, a single dose of a monovalent 2009 H1N1 flu vaccine was administrated to pregnant women, and a high seroprotection rate was reported.
