A Comparison of One Versus Two Doses of Influenza Vaccine in Children 5-8 Years of Age

Currently, two doses of influenza vaccine are recommended for children younger than 9 years
receiving influenza vaccine for the first time. While the scientific support for 2 doses of
vaccine in infants and toddlers is sound, the need for 2 doses of vaccine for adequate
immunogenicity in older children is less certain. If the immunogenicity of a one-dose vaccine
regimen is comparable to a two-dose regimen, then one dose would be preferable for reasons of
safety, practicality and economics, and would reduce a major barrier to vaccination in this
injection-adverse age group. This study compared the immunogenicity and reactogenicity of one
versus two doses of influenza vaccine in children aged 5 to 8 years old receiving influenza
vaccine for the first time. All children enrolled in the study received two doses of vaccine,
and the immune response after one dose of vaccine was compared to the immune response after
two doses of vaccine.

Inclusion Criteria:

- Immunocompetent children who are at least 5 and no more than 8 years of age on the
date of the first vaccination.

- Parents able to give informed consent and child available for all study visits.

- Family able to understand and comply with planned study procedures.

- Family must have telephone accessibility.

Exclusion Criteria:

- Previous receipt of influenza vaccine of any kind (shot or nasal spray).

- Active cancer or blood system abnormalities such as leukemia.

- Immunocompromising illnesses or current receipt of immunosuppressive agents

- Allergy to eggs or egg protein, or to gentamicin (an antibiotic that is present in
trace amounts in the vaccine).

- Any acute or chronic condition that (in the opinion of the investigator) would render
vaccination unsafe or would interfere with the evaluation of responses.

Temporary Exclusion Criteria:

Acute disease, defined as the presence of moderate or severe illness with or without fever,
at the time of enrollment. Influenza vaccine may be administered to children with minor
illnesses, such as diarrhea, mild upper respiratory infection and low-grade febrile illness
with an oral temperature <100.4 F.