The purpose of this study was to evaluate dose-related safety, reactogenicity and immunogenicity of FluBlok trivalent recombinant baculovirus-expressed hemagglutinin influenza vaccine, administered to healthy children aged 6 to 59 months.

Influenza has been identified as a major health problem in young children. Influenza related hospitalizations are very high in children less than 24 months of age and children age 24-59 months have a high rate of medical care utilization due to influenza. Recently, it has been noted that there are deaths attributable to influenza even in previously healthy children. Recent CDC recommendations reflect this growing awareness of the impact of influenza in children and state that virtually all children less than 18 years of age should receive annual influenza vaccination.

Currently available licensed trivalent influenza vaccines (TIVs) are prepared from viruses that are grown in embryonated hens' eggs. Alternative substrates for vaccine production are desirable in order to reduce the vulnerability of and to expand influenza vaccine supply. Recombinant DNA techniques allow for expression of the influenza hemagglutinin (rHA) by baculovirus vectors in insect cell cultures. Advantages of this technique include speed of production, absence of egg protein, and a highly purified product.

Inclusion Criteria:

1. The subject was:

   1. aged 6-59 months old (inclusive) at enrollment.
   2. in good health (and not on any chronic medications), as determined by medical history and a history directed targeted physical examination.
   3. naïve for previous influenza vaccination prior to study enrollment.

2. Parents or guardians must:

   1. be able to understand and comply with planned study procedures and be available for all study visits.
   2. provide written consent prior to initiation of any study procedures, and subject may provide written assent as appropriate.

Exclusion Criteria:

1. a known allergy to eggs or other components of the vaccine or sensitivity or allergy to latex.
2. a history of severe asthma or more than three previous wheezing episodes.
3. be undergoing immunosuppression as a result of an underlying illness or treatment.
4. an active neoplastic disease or a history of any hematologic malignancy.
5. be using oral or parenteral steroids, inhaled steroids or other immunosuppressive or cytotoxic drugs. Note: Subjects on nasal or topical steroids will be allowed to enroll in this study.
6. a history of receiving influenza vaccine or plans during the study to receive influenza vaccine outside the study.
7. a history of receiving immunoglobulin or other blood product within the 3 months prior to enrollment in this study.
8. received any other licensed vaccines within 2 weeks (for inactivated vaccines) or 4 weeks (for live vaccines) prior to enrollment in this study.
9. have an acute or chronic medical condition that, in the opinion of the investigator, would render vaccination unsafe or would interfere with the evaluation of responses (these conditions include, but are not limited to: known chronic liver disease, significant renal disease, unstable or progressive neurological disorders, diabetes mellitus, and transplant recipients).
10. a history of severe reactions following immunization.
11. an acute illness, including an axillary temperature greater than 100.0*F, within 3 days prior to vaccination.
12. received an experimental vaccine or medication within 1 month prior to enrollment in this study, or expect to receive an experimental vaccine, medication, or blood product during the 6-month study period.
13. any condition that would, in the opinion of the investigator, place them at an unacceptable risk of injury or render the subject unable to meet the requirements of the protocol.
14. a history of Guillain-Barré syndrome.
15. be participating concurrently in another clinical trial (either in active phase or in follow-up phase).