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.