This may be relevant to the discussion of trace & test:
Enhanced Contact Investigations for Nine Early Travel-Related Cases of SARS-CoV-2 in the United States
For 9 index travel-related cases Jan 19-Jan 30, they identified 404 close contacts to monitor (additional 149 low-risk or out-of-jurisdiction contacts were not monitored), 159 of which had at least one RT-PCR test as part of the process. Of those, it appears the only secondary infections were 2 spouses (2/15 = 13% of household members of the 9 cases).
Referring to a subset of 338:
"Of these 338 close contacts, 15 (4%) were household contacts, 163 (48%) were HCP, 95 (28%) were community contacts exposed in a healthcare setting, and 65 (19%) were community contacts exposed in another setting"
Referring to a couple where the travel-associated case got symptom one day after return, and the spouse got symptoms 3 days later:
"the travel-associated case patient wore a face mask and used a separate bedroom and
bathroom even prior to developing symptoms, although the couple did share a meal and spent extended time in
the car together"
(The other couple's situation is more confounded. They did not practice isolation.)
There are more details about exposure of other household members of the 9.
I saw no information as to the geographic region of any of the cases.
One can imagine that health care workers might be traced for multiple exposures.
Enhanced Contact Investigations for Nine Early Travel-Related Cases of SARS-CoV-2 in the United States
For 9 index travel-related cases Jan 19-Jan 30, they identified 404 close contacts to monitor (additional 149 low-risk or out-of-jurisdiction contacts were not monitored), 159 of which had at least one RT-PCR test as part of the process. Of those, it appears the only secondary infections were 2 spouses (2/15 = 13% of household members of the 9 cases).
Referring to a subset of 338:
"Of these 338 close contacts, 15 (4%) were household contacts, 163 (48%) were HCP, 95 (28%) were community contacts exposed in a healthcare setting, and 65 (19%) were community contacts exposed in another setting"
Referring to a couple where the travel-associated case got symptom one day after return, and the spouse got symptoms 3 days later:
"the travel-associated case patient wore a face mask and used a separate bedroom and
bathroom even prior to developing symptoms, although the couple did share a meal and spent extended time in
the car together"
(The other couple's situation is more confounded. They did not practice isolation.)
There are more details about exposure of other household members of the 9.
I saw no information as to the geographic region of any of the cases.
One can imagine that health care workers might be traced for multiple exposures.