Immune Response To Intranasal Influenza Vaccination

Inclusion Criteria: * Healthy children (age range ≥2 and \<18 years old) or adults (\>18-59 years old) as concluded from the medical history, physical examination, and clinical judgment) scheduled for tonsillectomy ; * Signed informed consent from the subject or both parents/ both guardians and from subjects aged 12 years and older; * Subjects or guardians able to understand and comply with the study protocol and complete the Adverse Event Form: * Subjects able to attend the scheduled visits. Exclusion Criteria: * Persons with a history of anaphylaxis or serious reactions to any vaccine; * Person with known hypersensitivity to any of the vaccine components (e.g. gelatin, gentamicin, eggs or egg proteins (e.g. ovalbumin); * Persons who are pregnant * Persons who have had a temperature \>38oC during the previous 72 hours; * Persons who have had an acute respiratory infection during the last 7 days; * Persons who are clinically immunodeficient due to conditions or immunosuppressive therapy such as: acute and chronic leukaemias; lymphoma; symptomatic HIV infection; cellular immune deficiencies; and high-dose corticosteroids; * Persons with severely immunocompromised family members; * Persons with severe asthma or active wheezing.