New York, Mar 13 (IANS): Researchers have found that a women who travelled from China to the US passed on the novel coronavirus to her husband in the country's first known person-to-person transmission, according to a study.
The Person-to-person transmission occurred between the couple who had prolonged, unprotected exposure while woman was symptomatic, the study, published in the journal The Lancet, said.
"This report suggests that person-to-person transmission might be most likely to occur through unprotected, prolonged exposure to an individual with symptomatic COVID-19," said co-lead researcher Jennifer Layden, Chief Medical Officer of the Chicago Department of Public Health.
According to the researchers, on January 23, Illinois reported the state's first laboratory-confirmed case (index case) in the woman in her 60s who returned from the Chinese city of Wuhan, the epicentre of the outbreak, in mid-January.
Subsequently, the first evidence of secondary transmission in the US was reported on January 30, when her husband, who had not travelled outside the US, had also tested positive.
Public health authorities conducted an intensive epidemiologic investigation of the two confirmed cases.
This study describes the clinical and laboratory features of both patients and the assessment and monitoring of several hundred individuals with potential exposure to the disease.
In total, 372 individuals were identified as potential contacts --347 of them were actively monitored after confirmation of exposure to the woman or her husband on or after the day of symptom onset.
There were 25 people that had insufficient contact information to complete active monitoring.
A convenience sample of 32 asymptomatic healthcare personnel contacts were also tested.
These 347 contacts underwent active symptom monitoring for 14 days following their last exposure.
Of these, 43 contacts who developed fever, cough, or shortness of breath were isolated and tested for coronavirua, as well as asymptomatic healthcare professionals. All 75 individuals tested negative.
On December 25, 2019, the female patient travelled to Wuhan where she visited a hospitalised relative and other family members with undiagnosed respiratory illness.
On her return to the US on January 13, 2020, she experienced six days of mild fever, fatigue, and cough before being hospitalised with pneumonia and testing positive for the coronavirus.
Prior to hospitalisation she was living with her husband who has chronic obstructive pulmonary disease (COPD) and chronic cough.
These conditions made it difficult to determine the timing of his symptom onset related to COVID-19.
Eight days after his wife was admitted to hospital, the husband was also hospitalised with worsening shortness of breath and coughing up blood, and also tested positive, the researchers said.
According to the study, both patients recovered and were discharged to home isolation, which was lifted 33 days after the woman returned from Wuhan, following two negative tests taken 24 hours apart.