Within any population, there is genetic variation. Viruses are no different. Some versions of the virus will be very slightly more dangerous to human health – more virulent – others less so. If the conditions are right, the slightly more virulent ones will begin to predominate and cause more damage.

 A pathogen, or disease-causing organism, does not “want” to kill its host. Its only evolutionary goal is to survive and reproduce, and if it has to kill to achieve that aim, then so be it. It causes harm because it needs its host’s cellular machinery to replicate and transmit to a new host. We feel sick because it’s siphoning off our bodily resources, and because of our own immune response.

When a novel pathogen emerges in humans, having jumped from an animal reservoir, it is not adapted to us. If it is too virulent, it risks immobilizing its host through illness or death before it can spread to a new one; not virulent enough, and it’s a weak transmitter – another evolutionary dead end. Scientists have recently demonstrated that a successful pathogen is one that evolves to an intermediate level of virulence so that it can spread without causing too much damage.

Source: https://www.theguardian.com/commentisfree/2020/nov/19/coronavirus-evolving-deadlier-evidence-social-distancing-covid-19?CMP=Share_AndroidApp_Other
Location: India

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