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contact tracing

  • 14 May 2020
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I recently completed the course on Contact Tracing,  a course related to a methodology to reign in the spread of Covid 19. During the course there was a segment with an interface between an interviewer and a “Contact.”  As time will have passed between the “contact” and the “case” prior to the interview there is a possibility that the “contact” will have become infected from the “case” (the reason for the interview.) If the “contact” has become infected but is asymptomatic they likely are not focusing on other contacts they have had since their interface with the “case.” The course should include a segment that would ask the “contact” to recall, while they can still remember, the people they have interfaced with since their interface with the “case” in the event they later test positive. 


2 replies

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Hello,

I had that same thought as you but ultimately agreed with the protocol.

This is my rationale.

1.)  The period for stopping transmission by limiting contact is 2 days - this is the window of opportunity.

2.)  The concern that the contact may become an asymptomatic spreader is mitigated by the 14 day quarantine.  14 days is equal to the maximum incubation period before onset of symptoms within the 95% distribution curve.

3.)  The period of infectiousness is -2 days before symptoms and throughout the illness, which may be as little as 10 days.

4.)  There has not been adequate study of asymptomatic transmission but there has been a lot of tracing globally.

This leads me to believe that given the very small window of opportunity and the limited amount of contact tracers (in the US), that the global data (assumption on my part) supports that transmission is statistically aligned by the contact tracing methodology.  If it were not, then efforts to suppress by contact tracing would be mysteriously unsuccessful in a statistically significant manner.

However, when the pandemic cools down a little and resources are in surplus, I would not be surprised if your observation isn’t incorporated into a study or five.  South Korea is well positioned to answer this question with its digital tracing and high capacity for PCR testing.  The questioned you pose will yield more than one PhD in more than one field.

 

Caveat - I am assuming that the Hopkins data is accurate at the time of publication.

 

Cheers and be well - great thought and thanks for sharing!

 

Tom 

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I agree with Tom that there will be no spread of the virus from the contact once and after the 14 days of quarantine is initiated. However, during the period of interface between the “case” and the “contact” but prior to the quarantine the “contact” may have become infected and is contagious but asymptomatic. During this period the “contact” (a new case) likely had other interactions.  If we wait until the newly infected “contact” (new case) displays symptoms prior to a follow-up the new case’s recall might be diminished making the contact tracing process more difficult. 

My suggestions is that the interviewer ask the “contact” about his or her interactions for the period between the interplay with the “case” and beginning of the quarantine. In this way the “contact” (possible new case) could likely provide a more thorough recall of their interactions and with whom. 

 

Len 

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