title: Influenza vaccination of pregnant women protects them over two consecutive influenza seasons in a randomized controlled trial.
abstract: We assessed the persistence of hemagglutinin inhibition (HAI) antibodies and the vaccine efficacy (VE) of trivalent inactivated influenza vaccine (IIV3) following vaccination of a cohort of pregnant South African women during a second influenza season.
  
  
  
  A cohort of women who participated in a randomized placebo-controlled trial on the safety, immunogenicity and efficacy of IIV3 in 2011 had HAI titers measured in 2012 and were monitored for influenza illness until the end of 2012.
  
  
  
  The proportion of women with HAI titers ≥1:40 was significantly greater in vaccinees (63%) compared to placebo-recipients (22%; p < 0.001). VE in 2012 was 63.8% (95% confidence interval [95%CI]: -33.7%, 90.2%); combined VE for 2011 and 2012 was 58.3% (95%CI: 0.2%, 82.6%).
  
  
  
  The majority of women who received IIV3 during pregnancy had HAI titers above the putative threshold for protection against influenza illness one year after vaccination and showed a trend towards protection against influenza disease.
authors.affiliation: a Department of Science and Technology/National Research Foundation, Vaccine Preventable Diseases , University of the Witwatersrand , Johannesburg , South Africa.|b Respiratory and Meningeal Pathogens Research Unit, Medical Research Council , University of the Witwatersrand , Johannesburg , South Africa.|c Julius Global Health, Julius Center for Health Sciences and Primary Care , University Medical Center Utrecht , Utrecht , The Netherlands.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Mutsaerts
authors.affiliation: a Department of Science and Technology/National Research Foundation, Vaccine Preventable Diseases , University of the Witwatersrand , Johannesburg , South Africa.|b Respiratory and Meningeal Pathogens Research Unit, Medical Research Council , University of the Witwatersrand , Johannesburg , South Africa.|d National Institute for Communicable Diseases, Division of National Health Laboratory Service , Centre for Respiratory Diseases and Meningitis , Johannesburg , South Africa.
authors.forename: Shabir A
authors.initials: SA
authors.lastname: Madhi
authors.affiliation: a Department of Science and Technology/National Research Foundation, Vaccine Preventable Diseases , University of the Witwatersrand , Johannesburg , South Africa.|b Respiratory and Meningeal Pathogens Research Unit, Medical Research Council , University of the Witwatersrand , Johannesburg , South Africa.
authors.forename: Clare L
authors.initials: CL
authors.lastname: Cutland
authors.affiliation: a Department of Science and Technology/National Research Foundation, Vaccine Preventable Diseases , University of the Witwatersrand , Johannesburg , South Africa.|b Respiratory and Meningeal Pathogens Research Unit, Medical Research Council , University of the Witwatersrand , Johannesburg , South Africa.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Jones
authors.affiliation: a Department of Science and Technology/National Research Foundation, Vaccine Preventable Diseases , University of the Witwatersrand , Johannesburg , South Africa.|b Respiratory and Meningeal Pathogens Research Unit, Medical Research Council , University of the Witwatersrand , Johannesburg , South Africa.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hugo
authors.affiliation: a Department of Science and Technology/National Research Foundation, Vaccine Preventable Diseases , University of the Witwatersrand , Johannesburg , South Africa.|b Respiratory and Meningeal Pathogens Research Unit, Medical Research Council , University of the Witwatersrand , Johannesburg , South Africa.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Trenor
authors.affiliation: d National Institute for Communicable Diseases, Division of National Health Laboratory Service , Centre for Respiratory Diseases and Meningitis , Johannesburg , South Africa.
authors.forename: Florette K
authors.initials: FK
authors.lastname: Treurnicht
authors.affiliation: c Julius Global Health, Julius Center for Health Sciences and Primary Care , University Medical Center Utrecht , Utrecht , The Netherlands.|e Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences , University of the Witwatersrand , Johannesburg , South Africa.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Klipstein-Grobusch
authors.affiliation: f Department of Pediatrics, Medicine and Pathology , University of Colorado , Aurora , CO , USA.
authors.forename: Adriana
authors.initials: A
authors.lastname: Weinberg
authors.affiliation: a Department of Science and Technology/National Research Foundation, Vaccine Preventable Diseases , University of the Witwatersrand , Johannesburg , South Africa.|b Respiratory and Meningeal Pathogens Research Unit, Medical Research Council , University of the Witwatersrand , Johannesburg , South Africa.
authors.forename: Marta C
authors.initials: MC
authors.lastname: Nunes
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D005260:Female; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D010919:Placebos / Q000008:administration & dosage; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control*; D013019:South Africa; D016896:Treatment Outcome; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D010919:Placebos; D015164:Vaccines, Inactivated
keywords: Influenza vaccine; efficacy; immunogenicity; maternal immunization