00:00If you're identifying somebody who has been exposed to the illness
00:03and you're avoiding them exposing other people to the disease,
00:06then you're going to cut the chain of transmission.
00:08And that's really the ultimate objective that we have in any outbreak response.
00:30So in Ebola, when someone was identified as a confirmed case,
00:40you would go in and do a pretty lengthy interview
00:44to try to get a listing of all of those contacts.
00:47The person you're interviewing obviously has just received
00:51some bad news and could be in crisis, is probably going to be a bit distressed.
00:56And so you have to bring in a level of sensitivity to the interview process
01:02while at the same time trying to be as exhaustive as possible
01:05in listing the places and the people that that person has interacted with
01:10since the onset of the illness.
01:11You want to ask questions about their routine activities,
01:15pretty much covering the entire length of time since the onset of the illness
01:20up until the point of the interview.
01:22So asking what's their routine, have they been out of the house,
01:25who's in the house with them, have they interacted with people at a store,
01:30what stores do they go to?
01:46So once we've contacted these contacts,
01:48they enter into a monitoring period where you have a team of contact tracers
01:55that have a list of contacts that they are responsible for following up with.
02:00In Congo and the Ebola contacts, we were following up with contacts at least twice a day,
02:05so once in the morning and once at night
02:07to see if there had been a change in their health status
02:10and if they developed any symptoms.
02:12So the purpose of this regular check-in is to detect cases as early as possible
02:19to avoid exposing other people.
02:22And the length of follow-up for contacts can depend on the disease.
02:26In Ebola, there's a 21-day incubation period,
02:29which means it's 21 days between when you've been exposed to the virus
02:34and you can start to develop symptoms.
02:43As a public health official,
02:45you always need to follow the principle of medical confidentiality.
02:49You never want to share details of a person who has been a confirmed case
02:54because that would violate a code of ethics.
03:07We saw a really strong link between the strength of our contact tracing system
03:13and the spread of the disease.
03:14If we had enough contact tracers on the ground,
03:18if they were doing good information sessions,
03:21and if we were consistently following up with contacts,
03:24then you would see a cut in the chain of the transmission.
03:27Alternatively, at times where we struggled with different pieces of this process,
03:32you would see the disease spread and more cases start to arise.
03:48There was a period of time where people thought that diseases that were transmitted through
04:07respiratory illnesses would be more difficult to use contact tracing,
04:11but the principles are the same.
04:13The idea is to have early detection of a case,
04:16to isolate that case, and to test them.
04:19We want to be doing anything we can to cut the chain of transmission
04:22and to prevent unnecessary illness and death.
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