Fig. 1.

Proportion of disagreement (with 95% confidence intervals) between positive LFT and confirmatory PCR, over time (top panel), proportion of all tests positive over time (middle panel), concordant positive proportion by age (bottom left) and the relationship between discordant positive proportion and proportion of all tests positive (bottom right). Confirmatory PCR was determined as a PCR within a 2-day window of the positive LFT. The proportion of tests positive was calculated as all positives (either PCR or LFT) divided by all tests taken within the month for each age group. We have assumed, conservatively, that all void PCR results are discordant positives.