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HomeMedicineInvestigation into first person to person transmission of COVID-19 in US

Investigation into first person to person transmission of COVID-19 in US

Declared as a pandemic by the World Health Organization (WHO), the Coronavirus disease 2019 (COVID-19) is spreading at a rapid pace, and researchers are trying to quickly understand the pattern of spread.

Recent research published in The Lancet focuses on the first occurrence of person-person transmission of COVID-19 in the United States. A woman returning home from Wuhan, China in mid-January was Illinois’ first confirmed case of the virus. Several days later, her husband was the second confirmed case. Initial symptoms presented as a mild fever, fatigue, and a cough. The woman was hospitalized for pneumonia and subsequently tested positive for COVID-19. Eight days later, her husband was hospitalized for coughing up blood and shortness of breath and was also later diagnosed with COVID-19.

Various Illinois state health departments consulted with the US Centers for Disease Control and Prevention (CDC) for technical assistance and onsite investigations. The places that were visited by the infected couple were investigated, and records such as staffing and patient logs and security footage were obtained to identify additional individuals that may have been potentially exposed to the virus. In total, there were 372 potential contacts.

Of the several hundred, 347 people were assessed, categorized by risk, and actively monitored for 14 days after their last exposure to a patient with COVID-19. Exposure classifications were assigned based on criteria designated by the CDC and COVID-19 investigation team. Active symptom monitoring was done electronically, where the contacts received emails twice a day inquiring about their symptoms and self-measured temperature. If indicative symptoms (cough, shortness of breath, fever, etc.) were reported, or if the individual failed to report back, a phone call would be made by a public health official. Specimens were also collected and sent to the CDC for testing.

At the end of the study period, no additional cases of COVID-19 were identified through active symptom monitoring. In light of the index patient infecting her husband and the data collected, it is believed that person-person transmission likely occurs through unprotected and prolonged exposure with a symptomatic individual.

According to the researchers, factors such as illness severity, the extent of viral shedding (when the virus leaves the host body), and timing of exposure to a symptomatic patient may play an important role in virus transmission.

The researchers note that the data collected is extremely preliminary, as only one event of transmission is investigated. Furthermore, due to the standardized questionnaires that people needed to fill out, not all individuals with potential exposure to COVID-19 may have been identified. As previously indicated, people and places investigated relied on the memory of the couple. Lastly, the study took place before the CDC’s updated guidance recommendations for screening. The active symptom monitoring would not have detected any asymptomatic transmissions that may have occurred. 

Though vaccines are still in development, studies such as this can serve as guidelines for informing public health recommendations regarding type and duration of isolation for infected patients as well as create more focused contact tracing for potential cases.

Written by Stephanie Tsang

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Isaac Ghinai, Tristan D McPherson, Jennifer C Hunter, Hannah L Kirking, Demian Christiansen, Kiran Joshi, Rachel Rubin, Shirley Morales-Estrada, Stephanie R Black, Massimo Pacilli, Marielle J Fricchione, Rashmi K Chugh, Kelly A Walblay, N Seema Ahmed, William C Stoecker, Nausheen F Hasan, Deborah P Burdsall, Heather E Reese, Megan Wallace, Chen Wang, Darcie Moeller, Jacqueline Korpics, Shannon A Novosad, Isaac Benowitz, Max W Jacobs, Vishal S Dasari, Megan T Patel, Judy Kauerauf, E Matt Charles, Ngozi O Ezike, Victoria Chu, Claire M Midgley, Melissa A Rolfes, Susan I Gerber, Xiaoyan Lu, Stephen Lindstrom, Jennifer R Verani, Jennifer E Layden. First known person-to-person transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the USA. The Lancet, 2020; DOI: 10.1016/S0140-6736(20)30607-3

“The Lancet: Study Details First Known Person-to-Person Transmission of New Coronavirus in the USA.” EurekAlert!, 12 Mar. 2020,

Image by mattthewafflecat from Pixabay 



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