Enhanced Contact Investigations for Nine Early Travel-Related Cases of SARS-CoV-2 in the United States
Authors: Burke Rachel M. , Balter Sharon , Barnes Emily , Barry Vaughn , Bartlett Karri , Beer Karlyn D. , Benowitz Isaac , Biggs Holly M. , Bruce Hollianne , Bryant-Genevier Jonathan , Cates Jordan , Chatham-Stephens Kevin , Chea Nora , Chiou Howard , Christiansen Demian , Chu Victoria , Clark Shauna , Cody Sara , Cohen Max , Conners Erin E. , Dasari Vishal , Dawson Patrick , DeSalvo Traci , Donahue Matthew , Dratch Alissa , Duca Lindsey , Duchin Jeffrey , Dyal Jonathan W. , Feldstein Leora R. , Fenstersheib Marty , Fischer Marc , Fisher Rebecca , Foo Chelsea , Freeman-Ponder Brandi , Fry Alicia M. , Gant Jessica , Gautom Romesh , Ghinai Isaac , Gounder Prabhu , Grigg Cheri T. , Gunzenhauser Jeffrey , Hall Aron J. , Han George S. , Haupt Thomas , Holshue Michelle , Hunter Jennifer , Ibrahim Mireille B. , Jacobs Max W. , Jarashow M. Claire , Joshi Kiran , Kamali Talar , Kawakami Vance , Kim Moon , Kirking Hannah , Kita-Yarbro Amanda , Klos Rachel , Kobayashi Miwako , Kocharian Anna , Lang Misty , Layden Jennifer , Leidman Eva , Lindquist Scott , Lindstrom Stephen , Link-Gelles Ruth , Marlow Mariel , Mattison Claire P. , McClung Nancy , McPherson Tristan D. , Mello Lynn , Midgley Claire M. , Novosad Shannon , Patel Megan T. , Pettrone Kristen , Pillai Satish K. , Pray Ian W. , Reese Heather E. , Rhodes Heather , Robinson Susan , Rolfes Melissa , Routh Janell , Rubin Rachel , Rudman Sarah L. , Russell Denny , Scott Sarah , Shetty Varun , Smith-Jeffcoat Sarah E. , Soda Elizabeth A. , Spitters Chris , Stierman Bryan , Sunenshine Rebecca , Terashita Dawn , Traub Elizabeth , Vahey Grace E. , Verani Jennifer R. , Wallace Megan , Westercamp Matthew , Wortham Jonathan , Xie Amy , Yousaf Anna , Zahn Matthew 
Published: May 2020

Background

Coronavirus disease 2019 (COVID-19), the respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first identified in Wuhan, China and has since become pandemic. As part of initial response activities in the United States, enhanced contact investigations were conducted to enable early identification and isolation of additional cases and to learn more about risk factors for transmission.

Methods

Close contacts of nine early travel-related cases in the United States were identified. Close contacts meeting criteria for active monitoring were followed, and selected individuals were targeted for collection of additional exposure details and respiratory samples. Respiratory samples were tested for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction (RT-PCR) at the Centers for Disease Control and Prevention.

Results

There were 404 close contacts who underwent active monitoring in the response jurisdictions; 338 had at least basic exposure data, of whom 159 had ≥1 set of respiratory samples collected and tested. Across all known close contacts under monitoring, two additional cases were identified; both secondary cases were in spouses of travel-associated case patients. The secondary attack rate among household members, all of whom had ≥1 respiratory sample tested, was 13% (95% CI: 4 – 38%).

Conclusions

The enhanced contact tracing investigations undertaken around nine early travel-related cases of COVID-19 in the United States identified two cases of secondary transmission, both spouses. Rapid detection and isolation of the travel-associated case patients, enabled by public awareness of COVID-19 among travelers from China, may have mitigated transmission risk among close contacts of these cases.