Why tracing close contacts is key: Lessons from the US' Patient One

The coronavirus pandemic has forced the world to relook its interactions. Economies are on historic slowdowns, with governments pledging bailouts worth trillions of dollars. Even the world’s biggest economy, the US, is struggling to contain the virus initially called a ‘Chinese hoax’ by American President Donald Trump.

Currently, more than 19,775 cases have been recorded in the US, with 276 deaths so far. All indications show that the numbers will increase. As this happens, medical journal, Lancet, has published the findings of a study that details the first known person-to-person transmission of Covid-19, how it was passed on and most importantly what governments around the world can learn from the case.

On January 23, authorities in Illinois, USA, reported the State’s first laboratory-confirmed case of the novel coronavirus in a traveller who returned from Wuhan in mid-January. In a detailed study, Lancet traced her medical history and most importantly, the steps that were taken to trace almost all individuals who had come in contact with her in a bid to stem the spread of the virus. Of note, too, is that the first person-to-person transmission recorded in the US was also the state from which Kenya’s first coronavirus case came from.

Patient 1 is a woman in her 60s who travelled to Wuhan on December 25, 2019, and returned to Illinois on January 13, 2020, and who was not symptomatic while travelling. In Wuhan, she visited a hospitalised relative regularly and visited other family members who had undiagnosed respiratory illnesses, one of whom was later hospitalised with viral pneumonia.

Pneumonia

Six days after she first visited the hospitalised relative, she sought care at an outpatient clinic for fever, fatigue, and cough and was hospitalised that day for pneumonia. She was reported to public health authorities as a Person Under Investigation (PUI) some 17 days after she had visited her relative. She had also reported other symptoms, which also included nausea, abdominal discomfort, and dizziness, starting as early as six days before admission.

At the time though, little was known about the disease and the woman had frequent, close contact with her husband. Her husband had not travelled to Wuhan. She and her husband live together, eat together, share a bed, and have frequent face-to-face interactions. Face masks or other personal protective equipment were not used at the home.

When the husband was first interviewed after some 17 days, he reported no fever or change in chronic respiratory symptoms. On January 30, he tested positive. Then the hard work of tracing the contacts of these two patients started.

Public health investigators were able to assess exposure risk and actively monitor symptoms for 347 (93 per cent) of the 372 contacts, including 222 (94 per cent) of 236 contacts with exposure on or after the date of first positive specimen collection.

There were 25 people that had insufficient contact information to complete active monitoring. None of these individuals were found to have emergency department visits with fever, cough, or shortness of breath using near real-time surveillance data received from regional acute care hospitals for 14 days after their last exposure.

Data presented are for those actively monitored. Of these 347 contacts, 195 (56 per cent) were healthcare personnel and 152 (44 per cent) were community members. Although the majority of monitored contacts (228 of 347) had low-risk exposures, 119 (34 per cent) had exposures of medium risk or greater.

Although Patient 1 and 2 live together and were hospitalised in the same facility, and therefore shared several common contacts (65 shared community contacts from emergency department or outpatient waiting rooms and 28 healthcare personnel who interacted with both patients), they also had many unique contacts.

Patient 1 had 92 unique healthcare personnel contacts and 16 unique community contacts, including one household contact (Patient 2). Patient 2 had 75 unique healthcare personnel contacts and 71 unique community contacts, including 51 from outpatient waiting rooms. The majority of contacts (303 of 347 total monitored contacts and 195 of 222 monitored contacts on or after the date of first positive specimen collection) did not develop symptoms.

Additionally, surveillance data from Illinois acute care hospitals indicated that no asymptomatic monitored contacts or other contacts who could not be reached for active symptom monitoring presented to an emergency department with fever, cough or shortness of breath. During active symptom monitoring, 44 (13 per cent) of 347 total contacts became persons under investigation, including 27 (12 per cent) of 222 monitored contacts who had exposures on or after the date of first positive specimen collection.

Household contact

As a household contact, Patient 2 was the only community member who had a high-risk exposure. He became a person under investigation and subsequently the only other patient with Covid-19 in this investigation.

Of the remaining 43 under investigation, all tested negative for Covid-19 while symptomatic; 32 of these were healthcare personnel and 11 were community contacts. Although 18 (41 per cent) of 44 those put under investigation had low-risk exposures, 26 (59 per cent) had exposures of medium risk or greater. Thirty-two healthcare personnel contacts who were not put under investigation had specimens collected 7-14 days after their highest-risk exposure.

Home isolation for both patients was lifted 33 days after tests, following two sets of negative respiratory specimens collected 24 hours apart. Patient 1 wore a face mask in the emergency department waiting room and where she was placed on droplet precautions and for the first 10 hours after admission.

She was subsequently transferred to an isolation unit, where healthcare personnel entering the patient’s room were required to adhere to strict standards that included proper hand hygiene, gloves, gown, respirator and eye protection.