Seroprevalence was the proportion of individuals who had a positive result in the IgG band of the point-of-care test or, in separate analyses, who had a positive result in the immunoassay.

In sensitivity analyses restricted to participants with data on both tests, we estimated seroprevalence as the proportions of individuals who had a positive result in both tests (most specific approach) or in either test (most sensitive approach). We used these analyses to provide a seroprevalence range that either favours specificity (requiring a positive test in both assays) or sensitivity (considering positive results in either test).