Coronavirus and the Infinite Loop!

Fighting a pandemic is a series of concerted efforts. I had mentioned in a column for the Economic Times earlier that it rides on four pillars – Testing / Detection, Contact Tracing, Quarantine and Social Distancing. In isolation, each of them will appear different to what they are in unison and so, looking at it from an individual constituent point of view leads us to the old story of the six blindfolded people defining what they thought an elephant was by touching and feeling individual parts of the animal. Well, only talking about flattening the curve is missing the woods for the tree!

Possibility vs Probability

People who haven’t got the coronavirus infection yet have a possibility of getting it only because those who have already got it are roaming around. The infected could either directly contact the uninfected or share articles / common transport that could transmit it from them to the others. So, let us imagine there was a mechanism to track down each and every person who is, as of today, carrying the coronavirus – including those not showing symptoms, and if we were able to push them into a quarantine and let them out of quarantine only after the designated treatment is that cleared them of the infection, the issue stands solved! Because, with that finite number of people, we have arrested further spread! They come out without an infection and mix around with the majority of the world that isn’t infected. What is the probability of pulling this to perfection? 0.001%?

When you have very little probability of getting something done in a particular way, you will have to look for other ways to achieve that desired outcome. There begins the first of the four pillars – test as many people as possible before allowing them to mix around! However, we are already too late for that… because, we don’t have enough testing facility to screen all human beings for this virus. When we fail in detection, someone has already got it and has also passed it on – we have to do a harder job. Find each person who is detected, find each person who could have possibly been infected… reach out and make them aware that they could be in danger – both to themselves and to others! Well, even that fails! Because it is such a tough thing to do given the nature of movement of people – from congregations for religious reasons to faith driven gatherings, social catch ups, a buffet meal! So, we end up having leaks with contact tracing as well! Means, we still have people who are walking around spreading that virus!

If you lock things down, do you decrease the probability of spreading that virus? Of course yes! It automatically constrains so many people to a limited geographical area that spreading can certainly be contained! Is that possible – yes, if the governments mandate it, we have no choice! We have to obey!

Quarantine therefore appears in three variants – self, medical and policy based! Self-quarantine is nothing but telling yourself, stay at home! Medical quarantine is when you are one of those in the contact tracing exercise or when you already have been infected! Policy based quarantine is when the law of the land expects you to stay at home, even if you weren’t willing to self-quarantine! Does quarantine work – is it possible that the virus can still spread despite quarantine? Yes, there is a possibility! That happens when people break the quarantine and move around…it could have worked, but we behave in such a way that the probability of success is not 100%. That 0.01% leakage is enough for setting up another chain of infections. We will loop back into testing and contact tracing then!

Does social distancing help – it does help! The lesser you aggregate, the more is the probability of containing the spread. Is this possible to achieve, yes of course… but again, we probably need the law to push us to do this!!! Hence, a lock down, stay at home order – works both as a variant of quarantine and a huge contributor to achieving the social distancing.

Present vs Future

What we should also think of is whether any of our actions will lead to an infinite loop of Testing, Contact Tracing, Quarantine and Social Distancing. And a pandemic with an infinite loop is as big as saying – a species gets wiped out! If we don’t get the part on quarantine to perfection, we won’t win this battle. In order to get that to perfection, we should have got a 100% accuracy on contact tracing. So, probabilities are stacked against human race! What does the future look like then? And what can we do about it to avoid getting into an infinite loop?

We are already past that stage of testing and detection! First, we must stay indoors until a period of 27 days! I am sure we are now anchored to 14 days quarantine… but why 27? Reuters carried a story that a Chinese Provincial Government declared that they got a case with an incubation history of 27 days. Typical data science would say, that is an outlier case. Meaning, when you are looking at large samples, this one may be a one off and is not representative. We aren’t arguing about whether it is representative, whether it is statistically significant etc.! We are going back to the question – if there is a possibility that despite 14 days of medical quarantine, a contact who has been traced could show symptoms even on the 15th or 16th or 27th day after walking out of the quarantine facility, why in the world would we want to decrease even a decimal point from 100% probability of containing the pandemic?  I completely agree that every single person who is walking out of quarantine after 14 may carry a very low probability of becoming an infected person in the next 12 days. Given that the world anyway is on lock down at large, why do we want to leave that very low probability that this virus can come back again to even exist …?

Are we making sure we won’t get on an infinite loop?

I think this question matters than anything else when we take decisions – be it as individuals, groups or as governments!