TABLE 3.

H9N2 avian influenza virus vaccines

Vaccine typeTest systemNo. of doses/route/vaccine strain/scheduleNotable outcomes (Ab/CMI/efficacy/other)Reference
Inactivated whole virusBALB/c mice1 dose/i.m. with 10 μg formalin-inactivated A/Hong Kong/1073/99 (G1) or Ck/G9 (G9) ± alumBoth vaccines induced HI Ab titers of ≥1:40 to homologous virus in the absence of alum, HI Ab titers increased 6-12-fold in presence of alum; G1 vaccine induced Ab titers against both homologous and heterologous virus, G9 vaccine induced Ab titers only against G9 viruses/challenged i.n. 3 mo postvaccination, G1 vaccine provided complete protection against both homologous and heterologous challenge, G9 vaccine provided complete protection against homologous challenge and partial protection against heterologous challenge 114
Humans2 doses/i.m. with 7.5, 3.8, or 1.9 μg A/Hong Kong/1073/99 (H9N2) + mineral adjuvant/0 and 3 wkAfter first dose, protective Ab titers were not detected; after second dose, protective Ab titers of ≥1:40 were detected 76
Hamsters2 doses/i.p.a with 15 μg formalin-inactivated A/Hong Kong/1073/99 ± alum/0 and 3 wkHI and NAb titers were induced in vaccinated animals/challenged i.n. with homologous virus 4 wk after final vaccination, and all animals immunized with vaccine alone were completely protected against challenge (no virus detected in lungs 2 dpi); half of animals immunized with vaccine + alum were not protected 159
BALB/c mice2 doses/i.m. with 10 μg formalin-inactivated G9/PR8 reassortant ± alum/0 and 2 wkAfter 1 dose, high HI Ab titers (≥320) against G9 virus were detected, no HI Ab against heterologous G1 virus; after second dose, HI Ab titers of 1:80 detected against G1 virus, increased fourfold with alum/challenged i.n. with G9 or G1-like virus, complete protection against homologous G9 and heterologous G1-like virus after 2 doses ± alum 20
Humans2 doses/i.m. with 7.5, 15, or 30 μg A/Hong Kong/1073/99 whole-virus or subunit vaccine/0 and 3 wkHI geometric mean Ab titers did not differ between any doses on days 21 and 42 for the whole-virus vaccine or the subunit vaccine, HI and NAb titers were significantly lower in individuals born after 1968; 2 doses of either vaccine induced protective Ab titers in people born before 1968, and one dose of either vaccine induced protective Ab titers in people born before 1968/both vaccines were well tolerated without adverse side effects, subunit vaccine was better tolerated than whole-virus vaccine 181
Live attenuated virusBALB/c mice1 dose/i.n. with 105 TCID50b of G9-A/AA/6/60 ca reassortantElicited HI Ab titers against homologous virus (HI = 320) and heterologous virus (HI = 40) 4 wk postvaccination/challenged i.n. with 105 TCID50 of either homologous or heterologous virus, G9/AAca virus vaccine protected mice from virus challenge (no virus detected in URT or LRT) 19
  • a i.p., intraperitoneally.

  • b TCID50, 50% tissue culture infective dose.