An open label Phase I trial of a live attenuated H6N1 influenza virus vaccine in healthy adults

Vaccine. 2011 Apr 12;29(17):3144-8. doi: 10.1016/j.vaccine.2011.02.043. Epub 2011 Mar 4.


Background: We describe the results of an open label Phase I trial of a live attenuated H6N1 influenza virus vaccine ( Identifier: NCT00734175).

Methods and findings: We evaluated the safety, infectivity, and immunogenicity of two doses of 10(7) TCID(50) of the H6N1 Teal HK 97/AA ca vaccine, a cold-adapted and temperature sensitive live, attenuated influenza vaccine (LAIV) in healthy seronegative adults. Twenty-two participants received the first dose of the vaccine, and 18 received the second dose of vaccine 4 weeks later. The vaccine had a safety profile similar to that of other investigational LAIVs bearing avian hemagglutinin (HA) and neuraminidase (NA) genes. The vaccine was highly restricted in replication: two participants had virus detectable by rRT-PCR beyond day 1 after each dose. Antibody responses to the vaccine were also restricted: 43% of participants developed a serum antibody response as measured by any assay: 5% by hemagglutination-inhibition assay, 5% by microneutralization assay, 29% by ELISA for H6 HA-specific IgG and 24% by ELISA for H6 HA specific IgA after either 1 or 2 doses. Following the second dose, vaccine specific IgG and IgA secreting cells as measured by ELISPOT increased from a mean of 0.6 to 9.2/10(6) PBMCs and from 0.2 to 2.2/10(6) PBMCs, respectively.

Conclusion: The H6N1 LAIV had a safety profile similar to that of LAIV bearing other HA and NA genes, but was highly restricted in replication in healthy seronegative adults. The H6N1 LAIV was also not as immunogenic as the seasonal LAIV.

Publication types

  • Clinical Trial, Phase I
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adolescent
  • Adult
  • Antibodies, Viral / blood
  • Enzyme-Linked Immunosorbent Assay
  • Enzyme-Linked Immunospot Assay
  • Female
  • Hemagglutination Inhibition Tests
  • Humans
  • Immunization, Secondary / methods
  • Immunoglobulin A / blood
  • Immunoglobulin G / blood
  • Influenza Vaccines / administration & dosage
  • Influenza Vaccines / adverse effects*
  • Influenza Vaccines / immunology*
  • Leukocytes, Mononuclear / immunology
  • Male
  • Middle Aged
  • Neutralization Tests
  • Orthomyxoviridae / immunology*
  • Vaccination / methods
  • Vaccines, Attenuated / administration & dosage
  • Vaccines, Attenuated / adverse effects
  • Vaccines, Attenuated / immunology
  • Young Adult


  • Antibodies, Viral
  • Immunoglobulin A
  • Immunoglobulin G
  • Influenza Vaccines
  • Vaccines, Attenuated

Associated data