A clinical study to assess the immunogenicity and safety of a monovalent 2009 influenza A (H1N1) vaccine in an area with low-level epidemics of pandemic influenza

Hsiang Chi Kung, Kuo Chin Huang, Tsui Mai Kao, Yi Chien Lee, Feng Yee Chang, Ning Chi Wang, Yung Ching Liu, Wen Sen Lee, Hsing Jin Liu, Chin I. Chen, Chien Hui Chen, Li Min Huang, Szu Min Hsieh

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We conducted a multi-center, randomized, laboratory-blinded clinical trial in 185 healthy adults (60 years) to examine the immunogenicity and safety of different doses of an inactivated, monovalent, non-adjuvanted, split vaccine against the 2009 pandemic influenza A (H1N1) virus. The 186 adults were assigned to three treatment groups, i.e., one 15μg hemagglutination (HA) antigen dose, two 15μg or 30μg HA doses in 3 weeks apart, and the 107 elders were treated with two 15μg or 30μg doses in 3 weeks apart. Prior to the vaccination, 4.8% subjects had hemagglutination-inhibition (HAI) antibody titers of 1:40 or more. By day 21 post-vaccination of one dose of 15μg HA, the seroprotective rate was 95.1% and 75.5% in subjects 65 years of age, respectively; by day 21 post the second 15μg HA dose, the seroprotective rates were 93.2% and 73.1%, respectively. The seroprotective rates for recipients of 30μg HA antigen by day 21 were 95.2% for subjects 65 years of age, that was boosted to 98.3% and 80.4%, respectively with a second dose of 30μg HA antigen. No vaccine-related serious adverse events occurred. The data indicated a single 15μg HA dose of the vaccine induced a protective immune response in most adults, including the elders >60 years of age, and a booster dose at the third week did not render a higher level of antibody response.

Original languageEnglish
Pages (from-to)7337-7343
Number of pages7
Issue number45
Publication statusPublished - Oct 21 2010



  • 2009 Pandemic influenza A (H1N1)
  • Immune response
  • Vaccination

ASJC Scopus subject areas

  • Immunology and Microbiology(all)
  • Infectious Diseases
  • Public Health, Environmental and Occupational Health
  • veterinary(all)
  • Molecular Medicine

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