Single vaccine shot prevents H1N1

A single shot of H1N1 flu vaccine boosts immune response in pregnant women and at the same time protects neuronatal babies via the antibodies that get transferred through the placenta, a new study has revealed. The researchers studied the immune response of 107 pregnant women after they were injected with a single dose of non-adjuvant H1N1 vaccine. The team led by Odile Launey, the Director of vaccinology at the Centre for Clinical Investigation at Cochin Pasteur, carried out a vaccination study in order to demonstrate the immunogenicity, in other words the immune response in terms of the production of antibodies, after a single injection of a nonadjuvant A strain (H1N1) into women at 21 days and 42 days of gestation and to measure the transplacentary transfer of the mother's antibodies to neonatal babies. This study concerned women between 22 and 32 weeks of amenorrhea who were monitored in five French neonatal clinics after being injected into the arm with an injection of H1N1 A strain vaccine. Blood tests were carried out in order to measure the antibody counts protecting against the influenza virus. On delivery, a blood sample was taken from the umbilical cord in order to measure the quantity of influenza antibodies transmitted to the newly born. All events observed in mothers and babies during the study were recorded. Prior to vaccination, 19 percent of the patients already presented H1N1 strain antibodies at levels considered to be potective. Three and six weeks after vaccination, 98 per cent of the patients presented blood antibody counts considered being protective. On delivery and 3 weeks after delivery, the proportion of patients with antibody counts considered to be protective was between 92 per cent and 90 percent. The umbilical cord samples of newly born babies showed antibody counts considered to be protective in 95 percent of cases. "These results show that the influenza vaccine boosts the immune system in pregnant women and also protects newly-borns via transplacenta transfer," said Launay. The study has been recently published in the review Annals of Internal Medicine