- not capable of giving informed consent - unable to self-administer the sinus rinses and mouth washes - unable to have healthcare professional-led swabs or self-administer the oral, nasal and/or nasopharyngeal swabs - unable to send swabs to the study team via the approved methods described in participant information leaflet and protocol - under 18 years of age. - known hypersensitivity to iodine - at risk of aspiration due to an unsafe swallow - hyperthyroidism or other manifest thyroid diseases - herpetiform dermatitis (duhring's disease) - planned or undergoing radioiodine treatment - actively breastfeeding - pregnant

- not capable of giving informed consent - unable to self-administer the sinus rinses and mouth washes - unable to have healthcare professional-led swabs or self-administer the oral, nasal and/or nasopharyngeal swabs - unable to send swabs to the study team via the approved methods described in participant information leaflet and protocol - under 18 years of age. - known hypersensitivity to iodine - at risk of aspiration due to an unsafe swallow - hyperthyroidism or other manifest thyroid diseases - herpetiform dermatitis (duhring's disease) - planned or undergoing radioiodine treatment - actively breastfeeding - pregnant