Table. SARS-CoV-2 Positivity Rates Among Quarantined Student Contacts of Confirmed COVID-19 Cases.
| Quarantined student contacts of confirmed COVID-19 cases, No./total (%) | |||
|---|---|---|---|
| Elementary and middle school | High school | All grades | |
| Positive test result for SARS-CoV-2 by test day | |||
| 3 | 0/80a,b | 14/54 (25.9)b,c | 14/134 (10.4) |
| 9 | 6/257 (2.3) | 14/222 (6.3) | 20/479 (4.2) |
| 10 | 1/76 (1.3) | 15/128 (11.7) | 16/204 (7.8) |
| 11 | 0/105 | 1/31 (3.2) | 1/136 (0.7) |
| 12 | 1/11 (9) | 1/2 (50)d | 2/13 (15.4) |
| 13 | 0/1 | 0/3 | 0/4 |
| 14 | 0/1 | 1/2 (50)e | 1/3 (33.3) |
| Cumulative: days 9-14 | 8/451 (1.8)b | 32/388 (8.2)b | 40/839 (4.8) |
a
There were 33 student contacts of confirmed COVID-19 cases with negative test results on day 3 who were retested on day 9 (or thereafter). None had positive test results.
b
The comparisons between elementary and middle school vs high school for the positivity rates were significantly different (P < .001 using the Fisher exact test).
c
There were 24 student contacts of confirmed COVID-19 cases with negative test results on day 3 who were retested on day 9 (or thereafter). One had a positive test result.
d
There was 1 asymptomatic SARS-CoV-2–positive contact who had not been previously tested on day 3 or day 9.
e
There was 1 contact who received a negative test result on day 9 but became symptomatic on day 14 and had a positive SARS-CoV-2 test result.