Wikipedia:Reference desk/Archives/Science/2020 June 9

= June 9 =

Retrospective vs prospective Contact tracing
What is the difference between retrospective and prospective contact tracing. And what are the pros and cons of each? Does one tend to be used over the other for certain types of infectious disease? Clover345 (talk) 13:27, 9 June 2020 (UTC)
 * In short, retrospective tracing "looks back" to find (and isolate) source(s) of infection; prospective tracing "looks forward" to minimize transmission. See: Prospective cohort study. An example of a prospective contact tracing study: abstract.  Whereas: Retrospective contact tracing aims to identify the source of transmission for a newly identified case to ensure all ongoing chains of transmission are known and monitored. 107.15.157.44 (talk) 18:35, 9 June 2020 (UTC)


 * If I understand correctly, contact tracing in general (for disease control) utilizes both simultaneously; studies utilizing one methodology and not the other are mainly for research and increased understanding. 107.15.157.44 (talk) 18:51, 9 June 2020 (UTC)


 * Somewhat simplistically stated: if there is a new patient with some contagious disease, then, in retrospective contact tracing, the tracer tries to figure out by whom this patient got infected. That person is a spreader and should be isolated so that they do not infect more people. In prospective contact tracing, the tracer tries to figure out who the patient may have met since they became infectious, and thereby unknowingly may have infected. These contacts should be monitored, so that they can be isolated (and if necessary treated) when they develop symptoms. Usually, retrospective tracing will additionally involve prospective contact tracing of any identified spreader. So, symbolically, if an arrow stands for transmission, and P is the patient, retrospective contact tracing aims to solve X→P for X, whereas prospective contact tracing looks at potential P→X transmissions. --Lambiam 21:06, 9 June 2020 (UTC)


 * Thanks, my question mainly came about from this article which claims Japan used a cluster containment method using retrospective contact tracing to contain clusters of COVID cases. Would they in reality have also used prospective contact tracing? Clover345 (talk) 00:04, 10 June 2020 (UTC)
 * I don't have access to that article, but using retrospective contact tracing doesn't necessarily exclude proactive contact tracing. Any effective cluster containment would require some of both, I imagine. 107.15.157.44 (talk) 00:44, 10 June 2020 (UTC)