• Melissa A Rolfes, Carlos G Grijalva, Yuwei Zhu, Huong Q McLean, Kayla E Hanson, Edward A Belongia, Natasha B Halasa, Ahra Kim, Jennifer Meece, Carrie Reed, H Keipp Talbot, and Alicia M Fry.
• MMWR Morb. Mortal. Wkly. Rep. 2021 Jan 1; 69 (5152): 1633-1637.

AbstractTo prevent further transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), CDC currently recommends that persons who have been in close contact with someone with SARS-CoV-2 infection should quarantine (stay away from other persons) for 14 days after the last known contact.* However, quarantine might be difficult to maintain for a prolonged period. A shorter quarantine might improve compliance, and CDC recommends two options to reduce the duration of quarantine for close contacts without symptoms, based on local circumstances and availability of testing: 1) quarantine can end on day 10 without a test or 2) quarantine can end on day 7 after receiving a negative test result.† However, shorter quarantine might permit ongoing disease transmission from persons who develop symptoms or become infectious near the end of the recommended 14-day period. Interim data from an ongoing study of household transmission of SARS-CoV-2 were analyzed to understand the proportion of household contacts that had detectable virus after a shortened quarantine period. Persons who were household contacts of index patients completed a daily symptom diary and self-collected respiratory specimens for 14 days. Specimens were tested for SARS-CoV-2 using reverse transcription-polymerase chain reaction (RT-PCR). Among 185 household contacts enrolled, 109 (59%) had detectable SARS-CoV-2 at any time; 76% (83/109) of test results were positive within 7 days, and 86% (94 of 109) were positive within 10 days after the index patient's illness onset date. Among household contacts who received negative SARS-CoV-2 test results and were asymptomatic through day 7, there was an 81% chance (95% confidence interval [CI] = 67%-90%) of remaining asymptomatic and receiving negative RT-PCR test results through day 14; this increased to 93% (95% CI = 78%-98%) for household members who were asymptomatic with negative RT-PCR test results through day 10. Although SARS-CoV-2 quarantine periods shorter than 14 days might be easier to adhere to, there is a potential for onward transmission from household contacts released before day 14.

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