Table 1.

Classification of the space-time clusters according to the viral load of the cases involved. Within-cluster cases were identified by matching both geographically and temporally positive test subjects, geocoded at the residential address, with space-time clusters. For example, a cluster was classified as “all below 1 million” if all individuals tested positive within the cluster during its active period had a viral load below 1 million copies/ml.

For each cluster category, the total number of case clusters detected by prospective space-time scan statistics over the entire study period (March 2 to June 20) and the proportion of significant clusters (p ≤ 0.05) are reported.

Case cluster viral load category	Total number of clusters	Number of significant clusters
All below 1 million	106	33 (31.1%)
At least one between 1 million and 10 million	128	23 (17.9%)
At least one between 10 million and 100 million	125	13 (10.4%)
At least one between 100 million and 1 billion	659	128 (19.4%)
At least one between 1 billion and 10 billion	636	251 (39.4%)
At least one above 10 billion	30	9 (30.0%)
Total	1684	457