A while ago, some asshole with a blog had this to say about backward contact tracing:
The real question isn’t what happened within the family–that’s obvious. These also are the cases that are easy for D.C. to detect because the focus is on close contacts, not deep investigation. What we need to ask is how the person who brought COVID-19 to the party (literally) contracted it in the first place. Was it work? Dining out with friends? Because the good news, if it can be called that, is that we typically don’t have to go too many links back to find the superspreading event. Once we understand those, we can make better policy.
But until we reallocate some of our resources to really understanding how spread occurs, we’re left with broad brush generalities–which means our responses have to be broad too, even if not truly necessary. That leads to a political problem, since the city (and in fairness, no other states too) doesn’t want to have broad rollbacks. But broad rollbacks are the only policy option right now–or letting people get seriously sickened or die, since we don’t have the evidence to put any other policy options* on the table.
You’ll notice that some school-related cases are at the tips of the network, meaning they ‘brought’ the infection to the school: that is, they acquired COVID-19 in the outside community. But a fair number of the school-related cases are internal nodes of the network, and they served as conduits to other people outside of the school. In fact, several school-related cases had connections to a lot of other infected people.
This might have some relevance to whether schools can result in community-spread. That doesn’t necessarily mean we should close them, but it does put a certain crimp in the style of a certain economist who likes to opine about public health policy. Just saying.
With backward contact tracing, we often learn some very interesting–and often disturbing–things, such as people will still go to the gym if they have tested positive for COVID-19 (?!?), or airlines and airports will let people get on planes even if they have COVID-19 symptoms and have been in contact with people known to have COVID-19 (again, ?!?).
This is how you target certain interventions so we don’t need to do mass shutdowns, even if the targeted interventions might be draconian. Without this, we’re left guessing about what an effective intervention might be, and not instituting policies that actually could stop transmission.
This is yet another reason why we can’t have nice things.