Pediatric Household Transmission of Severe Acute Respiratory Coronavirus-2 Infection-Los Angeles County, December 2020 to February 2021.

This brief report presents transmission rates from a prospective study of 15 households with pediatric index cases of severe acute respiratory coronavirus-2 in Los Angeles County from December 2020 to February 2021. Our findings support ongoing evidence that transmission from pediatric index cases to household contacts is frequent but can be mitigated with practicing well-documented control measures at home, including isolation, masking and good hand hygiene.

Diagnostic Performance of an Antigen Test with RT-PCR for the Detection of SARS-CoV-2 in a Hospital Setting - Los Angeles County, California, June-August 2020.

Prompt and accurate detection of SARS-CoV-2, the virus that causes COVID-19, has been important during public health responses for containing the spread of COVID-19, including in hospital settings (1-3). In vitro diagnostic nucleic acid amplification tests (NAAT), such as real-time reverse transcription-polymerase chain reaction (RT-PCR) can be expensive, have relatively long turnaround times, and require experienced laboratory personnel.* Antigen detection tests can be rapidly and more easily performed and are less expensive. The performance† of antigen detection tests, compared with that of NAATs, is an area of interest for the rapid diagnosis of SARS-CoV-2 infection. The Quidel Sofia 2 SARS Antigen Fluorescent Immunoassay (FIA) (Quidel Corporation) received Food and Drug Administration Emergency Use Authorization for use in symptomatic patients within 5 days of symptom onset (4). The reported test positive percentage agreement§ between this test and an RT-PCR test result is 96.7% (95% confidence interval [CI] = 83.3%-99.4%), and the negative percentage agreement is 100.0% (95% CI = 97.9%-100.0%) in symptomatic patients.¶ However, performance in asymptomatic persons in a university setting has shown lower sensitivity (5); assessment of performance in a clinical setting is ongoing. Data collected during June 30-August 31, 2020, were analyzed to compare antigen test performance with that of RT-PCR in a hospital setting. Among 1,732 paired samples from asymptomatic patients, the antigen test sensitivity was 60.5%, and specificity was 99.5% when compared with RT-PCR. Among 307 symptomatic persons, sensitivity and specificity were 72.1% and 98.7%, respectively. Health care providers must remain aware of the lower sensitivity of this test among asymptomatic and symptomatic persons and consider confirmatory NAAT testing in high-prevalence settings because a false-negative result might lead to failures in infection control and prevention practices and cause delays in diagnosis, isolation, and treatment.