<qa>  What will be used to determine the total IgG and IgG subtypes?Subjects will be consented to participate in the study. They will complete a web-based baseline questionnaire. Participants will be given a nasal swab kit with instructions for obtaining swabs. Baseline blood 10mls will be drawn for influenza serology and for measurement of total IgG and IgG subtypes. An email will be sent to each participant within 24 hours of their enrolment to welcome them to the study. 