Coronavirus (COVID-19): modelling the epidemic (issue no.84)

Technical Annex

How have the Scottish Contact Survey panels been replenished?

Two new panels have been created from the recent recruitment and have run alongside current panels A & B since November 2021. The new panels have been combined with the established panels to maintain numbers and demographic representation.

Panels A and B have experienced a drop off of participants since commencement. Figure 20 shows the mean overall contacts for the established panels (A and B) compared against the combined panels (A2 and B2). The combined panels initially show higher overall contacts, by 17%, which is likely due to the new respondents maintaining participation amongst individuals with high contacts, whilst the original panels, A and B, have seen a significant drop off in contacts over time, likely losing these individuals.

Breaking down the contacts into settings, differences in results are seen for contacts in the other setting and at work. This supports the notion that the remaining participants in the established panels (A and B) have fewer commitments.

What levels of Covid-19 are indicated by wastewater data?

Table 2 provides population weighted daily averages for normalised WW Covid-19 levels in the weeks ending 21st December 2021 and 4th January 2022, with no estimate for error. This is given in Million gene copies per person, which approximately corresponds to new cases per 100,000 per day. Coverage is given as percentage of LA inhabitants covered by a wastewater Covid‑19 sampling site delivering data during this period^[13].