Hacker News Reader

Comment by danieltillett | Hacker News Reader

Mike my concern as a scientist about this app is it may not help much at this point. If it is only picking up people you spent more than 15 minutes talking to it is going to miss a lot transmission events.

Do we have the contact tracing people to actually make use of this data? Even if we did I can’t see how we are going to avoid the need to interview each positive case to find all the people they came into contact with for less than 15 minutes. How much value is being added?

I am not installing it purely because I am social distancing and won’t be spending 15 minutes talking to anyone face to face outside of my immediate family.

View on HN

> 15 minutes talking to it is going to miss a lot transmission events.

Honest question (as a scientist myself): is there any serious non-preprint literature on the time needed for a transmission event (I assume estimates will vary wildly)?

I beleive there is also a lack of literature on how useful a contact tracing app would be in the first place. Even for lack of studies, releasing the modelling and assumptions would be useful. Some considerations:

* Possible increase in false positives bogging down testing regime? * Surface-based (i.e. location-based) contact events (e.g. elevator button) * Effectiveness on health-care workers, who themselves will likely be in contact with infected people a lot, perhaps despite having sufficient PPE.

I get that it won't be perfect, and doesn't need to be perfect, but I'd at the least like to see some modelling to see what they've considered, and how likely useful the app will be.

Bluetooth penetrates walls, and travels some distance in all directions, so it will also record a lot of false transmission events, for example in blocks of units, offices, and on public transport. Most transmissions are to immediate family, who are easy to trace manually with the existing procedure.

The government says that if you are party to a (genuine or false) transmission event, you will be contacted by phone, but you will not be told the name of the person who tested positive to the virus. So how will you know if the event is genuine or not? It could be your neighbour on the other side of a common wall, or a colleague who works in the office next to yours -- in either case, no transmission. Also, they say you may be "advised to self-isolate". This is disingenuous -- you are more likely to be ordered to self-isolate under penalty of fines or gaol time. No mention of that in the glossy "Utopia" style promotional video, just happy young models having coffee.

Authorities here were quoted saying that family transmissions are 25% of the cases. Now I wonder, what is part of the remaining 75%?

Not that I know of as this is hard to study. What we have is a lot of case studies that transmission can occur in much less time than this including cases where there was no contact between the parties.

The best write up on this I have seen on this topic has been in Quillette [0]. I know Quillette gets attacked here from those on the left, but they do cover a wide range of topics (not all articles I agree with). They are pro-science and generally provide good references.

0. https://quillette.com/2020/04/23/covid-19-superspreader-even...

Thanks. An interesting and fascinating read. I hope more research is done on the topic: from my semi-untrained (I work in oncology, not in virology, although I studied the immune system for about four years in my career) there far more models around than experimental data (which is obviously far harder to gather correctly).

Non scientist here but I’ve been harping on about the same thing. Someone can cough this virus into my face in a matter of seconds. It would appear this 15 min contact duration minimum is perhaps based on outdated data and knowledge of transmissibility.

The client logs all encounters regardless of time or proximity. It just has to be in range. The 15 minute 1.5m conditions are done on the reporting side when a case is positive and data is uploaded.

Reply on news.ycombinator.com