Among the first 10 patients with travel-related confirmed COVID-19 reported in the United States, a total of 445 persons who had close contact with one of the 10 patients on or after the date of the patient’s symptom onset were identified.
Additionally, 19 (4%) of the 445 contacts were members of a patient’s household, and five of these 19 contacts continued to have household exposure to the patient with confirmed COVID-19 during the patient’s isolation period; 104 (23%) were community members who spent at least 10 minutes within six feet of a patient with confirmed disease; 100 (22%) were community members who were exposed to a patient in a healthcare setting; and 222 (50%) were healthcare personnel.
The Centers for Disease Control and Prevention (CDC) reviewed the active symptom monitoring of the 445 close contacts, consisting of daily telephone, text, or in-person inquiries about fever or other symptoms for 14 days following the last known exposure to a person with confirmed COVID-19, was conducted by local health jurisdictions.
During the 14 days of active symptom monitoring, 54 (12%) close contacts developed new or worsening symptoms deemed by local public health authorities to be concerning for COVID-19 and were thus considered persons under investigation (PUIs) and subsequently were tested for SARS-CoV-2. Two persons who were household members of patients with confirmed COVID-19 tested positive for SARS-CoV-2. This yielded a symptomatic secondary attack rate of 0.45% among all close contacts, and a symptomatic secondary attack rate of 10.5% among household members. Both persons with confirmed secondary transmission had close contact with the respective source patient before COVID-19 was confirmed and were isolated from the source patient after the patient’s COVID-19 diagnosis.
No other close contacts who were tested for SARS-CoV-2 had a positive test, including the five household members who were continuously exposed during the period of isolation of their household member with confirmed COVID-19.
An additional 146 persons exposed to the two patients with secondary COVID-19 transmission underwent 14 days of active monitoring. Among these, 18 (12%) developed symptoms compatible with COVID-19 and were considered PUIs. All tested negative, and no further symptomatic COVID-19 cases (representing tertiary transmission) have been identified.
Since Feb. 28, an increasing number of newly diagnosed confirmed and presumptive COVID-19 cases have been in patients with neither a relevant travel history nor clear epidemiologic links to other confirmed COVID-19 patients.
