We will approach potential childcare environments with pre-study information to inform parents of the study. Those sites that choose to take part will be asked to notify us if an index case of chickenpox has occurred and we will then contact the index case to take consent to take part in the study.

At this point we will also seek to take consent from the parents of any other children exposed to the index case in that room, following them up during the incubation period. Only those that develop clinical chickenpox will be asked to complete the data collection tool with any data on those who do not develop disease only retained to form denominator estimates.

Once consent is given, study personnel will provide a brief demographic questionnaire and baseline HRQoL measurement to the parent or guardian and assist them with any queries they may have.

Parents will be asked to complete this diary daily if their child develops chickenpox until they are back to what they would consider normal health. This will consist of illness severity questions and HRQoL questionnaires for the child and their parents taking approximately 15 min per day to complete.

They will be offered reminders by telephone/text/email contact on days 14 and 21 of incubation.

We found in the first season that recruitment via identification of index cases in nursery rooms did not work. The nurseries were very keen to be involved and let us know as soon as they had cases, but despite consenting 40 children who had been exposed to index cases there were no secondary cases of varicella. We have redesigned the study procedures to be entirely web-based. This will allow us to publicise the study website (chickenpox-study.co.uk) through the same nurseries (all pre-school childcare facilities within the central Bristol area) that we attempted to identify index cases in. The nurseries will promote this, emailing reminders to parents and displaying a poster. Parents whose children develop chickenpox can then visit this to first give consent, complete a retrospective question assessing their child’s baseline level of health and then start the same process of daily diaries until back to what they would consider their normal baseline. The website is open, so families with children not in a childcare setting are also able to sign up. We will promote the study through social media but will ask for a postcode so we can still understand where our subjects are from. Any community cases who get admitted to hospital will then be eligible for follow-up by the inpatient arm.

Children with chickenpox that did not require admission, will be recruited from the emergency department. After consent they will be asked to complete the same daily diaries until back to normal health.

Study teams will carry out daily review of the hospital census to prospectively identify potential patients with chickenpox or a secondary complication. These will include but not limited to patients with skin infections, haemorrhagic vesicular rash, disseminated purpura, staphylococcal scalded skin syndrome, cellulitis, abscess, pneumonia, osteomyelitis, septic arthritis, myositis, adenitis, fasciitis, hepatitis, severe anorexia/dehydration, eye involvement, neurological issues, haematological disturbances or Reye’s syndrome.5 Any patient identified though this method will be invited to join this QoL study.

Once consent is given, study personnel will provide a brief demographic questionnaire to the parent or guardian which will also ask them to retrospectively score their child’s HRQoL prior to illness.

Parents will be asked to complete this daily while in hospital, weekly once discharged from hospital for 1 month and then monthly until their child’s symptoms have completely resolved with a final contact again at 6 months (figure 1). The diary will consist of illness severity questions and HRQoL questionnaires for the child and their parents taking less than 5 min to complete. Children over the age of 7 years will be able to fill out their own QoL questionnaires themselves.

Schedule of diaries for hospitalised cases.

Parents will be offered reminder contact for the diary entries by phone/short message service/email, with the option of completing questions over the phone.

The study is planned to recruit for up to 12 months and end of study will be the date of last diary entry of the last participant (up to 6 months after the last participant discharged from hospital).