Viswanathan K's Thoughts

In the age of COVID-19, David Quammen’s 2012 book Spillover is beginning to be viewed as almost prophetic. The book is about the, er, spillover of diseases from animals to humans. The technical term for such inter-species diseases transfer is “zoonotic” . Such occurrences shouldn’t be surprising, he says: “Just as a lion might occasionally depart from its normal behaviour – to kill a cow instead of a wildebeest, a human instead of a zebra – so can a pathogen shift to a new target.” It’s just how nature operates. There are no rules: whatever works will happen.   The significance of zoonotic v/s non-zoonotic diseases in humans is this: “Zoonotic pathogens can hide (in other species).” Ergo, even if you eliminate it in all humans, it’s still out there (in other species). And so it can always come back, either as-is or with some mutation. This explains why we could eliminate smallpox: it is not a zoonotic pathogen. In other words, it had nowhere else (no other species) to...

In a recent blog , I said that the coronavirus wasn’t an epidemic yet, regardless of the panic and fear. Sadly, now it’s official, writes Ed Yong: the WHO declared it a “public-health emergency of international concern” (PHEIC) — a designation that puts it in the same bucket as the infamous epidemics of H1N1 swine flu, polio, Ebola, Zika, and Ebola again. In his article, Yong focusses on the following aspect: “Each epidemic is also different, and each is a mirror that reflects the society it affects.” Let’s explore that line in detail. Coronavirus seems to be spreading at a blistering pace compared even to SARS, which for all the hue and cry, infected 8,100 people in 8 months . But that’s not an apples to apples comparison, say many. Back then in 2002-03, the world didn’t know how fast and how wide a new virus could spread. Today, we have panic, which leads to more people checking in for anything resembling the symptoms. Plus, the number of people flying across the world ha...

The coronavirus, the epidemic(?) that’s been spreading in (and from) China. But how contagious is it exactly? Ed Yong wrote this superb article explaining the number used to measure such things in general. It is called the “basic reproduction number”, or just R0, pronounced R- nought : “R0 is the average number of people who will catch the disease from a single infected person, in a population that’s never seen the disease before. If R0 is 3, then on average every case will create three new cases.” In case of the coronavirus, 6 research teams have come up with a value for R0, spread over a wide range from 1.4 to 5.5. Why such a discrepancy in values? Because in the early days, there’s just not enough data: “Some people might have been infected without showing symptoms. Others might not have reported their symptoms to health authorities.” Unfortunately, a Harvard doctor seized upon the R0 value of 3.8 from one of those studies and called it “thermonuclear pandemic...