title: The safety and immunogenicity of two hepatitis B vaccine formulations (thiomersal-free and thiomersal-containing) in healthy vietnamese infants: a phase III, prospective, single-blinded, randomized, controlled trial.
abstract: BACKGROUND
  To evaluate the safety and immunogenicity of the thiomersal-free (TF) and thiomersal-containing (TC) formulations of Hepavax-Gene in healthy Vietnamese neonates.
  
  
  METHODS
  A single-blind, randomized, controlled study in Ho Chi Minh City, Vietnam. Healthy infants, born after a normal gestational period (37-42 weeks) to hepatitis B surface antigen-negative mothers, participated in the study. Subjects were randomly allocated in a 1:1 ratio to receive either Hepavax-Gene TC or Hepavax-Gene TF using a standard 0-1-6-month administration schedule. Postvaccination blood samples were taken at months 1, 6 and 7. Parents/legal guardians recorded solicited local and systemic adverse events up to 4 weeks after each vaccination.
  
  
  RESULTS
  Very high proportions of subjects were seroprotected. Seroprotection rates at 1, 6 and 7 months were all above 95% using a 10 IU/L cutoff, and were mostly above 90% using a 100 IU/L cutoff. Seroprotection rates between the 2 formulations were equivalent within a 5% margin for either cutoff titer both after 6 and 7 months. There were no significant differences in the number of adverse events reported between the 2 formulations. Safety results were in line with previous reports for Hepavax-Gene. Both formulations of Hepavax-Gene were well tolerated. There were no local adverse events reported in the TF group. No serious adverse events were reported during the study.
  
  
  CONCLUSIONS
  The thiomersal-free formulation of Hepavax-Gene was noninferior to the thiomersal-containing formulation of Hepavax-Gene in terms of immunogenicity. There was evidence that the thiomersal-free vaccine was associated with fewer local adverse events.
authors.affiliation: From the *Hung Vuong Hospital, Ho Chi Minh City, Vietnam; †Crucell Switzerland AG, Bern, Switzerland; and ‡Crucell Holland BV, CN Leiden, The Netherlands.
authors.forename: Nguyen Trong
authors.initials: NT
authors.lastname: Hieu
authors.forename: Michal
authors.initials: M
authors.lastname: Sarnecki
authors.forename: Jeroen
authors.initials: J
authors.lastname: Tolboom
mesh_terms: D000890:Anti-Infective Agents / Q000008:administration & dosage; D002626:Chemistry, Pharmaceutical; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology; D005260:Female; D064368:Healthy Volunteers; D006510:Hepatitis B Antibodies / Q000097:blood; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011446:Prospective Studies; D016037:Single-Blind Method; D013849:Thimerosal / Q000008:administration & dosage; D014611:Vaccination / Q000379:methods; D014744:Vietnam
chemical_list: D000890:Anti-Infective Agents; D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines; D013849:Thimerosal