Evaluation of the Safety and Immunogenicity of a Live Attenuated Virus Vaccine for the Prevention of H2N3 Influenza

Animal influenza viruses, such as the H1N1 and H5N1 viruses, typically infect animals like
birds or pigs, but these viruses can also infect humans. The recent outbreak of the H1N1
influenza virus demonstrates that it is possible for these viruses to cause a pandemic
outbreak in humans. Researchers are specifically interested in evaluating vaccines for H2
viruses, as these viruses caused a pandemic outbreak in humans in the late 1950s to 1960s.
In addition, over half of the world's current population has no previous exposure to related
viruses, which means a pandemic outbreak could pose a serious health risk as many people
would have no immunity against the virus. In 2006, an outbreak of H2N3 infection occurred in
pigs in the Midwest United States. While no humans contracted the virus during that
outbreak, it remains a concern for researchers in the event that the virus ever spreads to
humans. The purpose of this study is to evaluate the safety and immunogenicity of two doses
of an experimental H2N3 vaccine, H2N3 MO 2006/AA ca in healthy adults. This is a live
attenuated vaccine, which means that participants will be exposed to small amounts of the
H2N3 vaccine virus and will need to remain isolated for at least 12 days when receiving the
vaccine to prevent spreading the virus to others.

This study will enroll healthy adults. Participants will receive two doses of the vaccine, 4
weeks apart, and will stay in an isolation facility during both 12-day vaccination periods.
Participants will be admitted to the isolation facility 2 days before they receive their
first vaccination. They will receive one nasal spray administration of the vaccine and will
be monitored for side effects. On various days while in the isolation facility, they will
undergo a physical exam, blood and urine collection, and a nasal wash procedure.
Participants will remain in the isolation facility for at least 9 days after receiving the
vaccine and possibly longer, until the nasal wash tests negative for the vaccine virus for 2
consecutive days. Participants will be readmitted to the isolation facility 26 days after
the first vaccination. They will receive a second vaccination and all study procedures will
be repeated. Participants will attend study visits 56, 82, and 208 days after the first
vaccination for follow-up health and safety monitoring, blood collection, and a nasal wash
procedure.