San Francisco and Oakland population characteristics.
In total, 83 participants with at least two COVID-19 symptoms were enrolled at the San Francisco, CA and Oakland, CA sites. Two participants were excluded from the analysis due to lost samples during transport for RT-PCR. Of the 81 participant specimens analyzed, 44.4% were from female participants (Table S1), with a median age of 32 years (interquartile range [IQR], 25, 44). The most frequently reported symptoms were muscle/body ache (61.7%), congestion/runny nose (60.5%), fatigue (56.8%), and headache (53.1%). The breakdown of duration of symptoms was 1 to 2 days in 37 participants (45.7%), 3 to 4 days in 38 participants (46.9%), and 5 days in 6 participants (7.4%).
San Fernando population characteristics.
In total, 270 participants with at least one COVID-19 symptom were enrolled at the San Fernando, CA site. Two participants were excluded from the analysis due to lost or spilled samples during transport for RT-PCR. Of the 268 participant specimens analyzed, 52.6% were from female participants (Table S2), and the median age was 35 years (IQR, 24, 50). The most frequently reported symptoms were sore throat (60.8%), headache (60.1%), congestion/runny nose (59.0%), and cough (54.9%). The distribution of duration of symptoms was 1 to 2 days in 109 participants (40.7%), 3 to 4 days in 127 participants (47.4%), and 5 days in 32 participants (11.9%).
Performance of the INDICAID COVID-19 rapid antigen test in symptomatic patients.
Of the total 329 participant specimens included in the analyses, 75 tested positive with the comparator laboratory-based RT-PCR test. The mean cycle threshold value was 20.79 ± 6.39.
The INDICAID rapid test demonstrated a PPA of 85.3% (95% confidence interval [95% CI], 75.6% to 91.6%) and an NPA of 94.9% (95% CI, 91.6% to 96.9%) when sample collection was conducted by a health care professional. There was a total of 11 false-negative INDICAID results that were not concordant with RT-PCR results; the mean threshold cycle (CT) value of the false-negative INDICAID specimens was 32.56 ± 4.59.