SARS-CoV-2 – A Threat or A Regular Infection
“Disease can rarely be eliminated through early diagnosis or good treatment, but prevention can eliminate disease.”
~Denis Parsons Burkitt
SARS-CoV-2 is very different from the 2002 SARS virus and MERS virus. Since transmission begins even before symptoms set in and well before the disease becomes severe, the transmission characteristic is decoupled from disease. As a result, the natural evolution process selects variants not based on how they cause disease but how they can escape neutralising antibodies.
The virus was novel and none in the world had any immunity in the beginning of the pandemic. But with millions being infected by the virus and millions being fully vaccinated, and some with a combination of natural infection and vaccination, the next variant has to necessarily exhibit higher immune escape to cause infection. This is the reason that the next variant will exhibit more immune escape than the Omicron variant.
Dr Roby P. Bhattacharyya from Massachusetts General Hospital, Boston and Dr William P. Hanage from Harvard T.H. Chan School of Public Health, Boston write in The New England Journal of Medicine that This meaningful but fairly small difference implies that Omicron, Alpha, and wild-type SARS-CoV-2 have similar intrinsic severity. Viruses don’t inevitably evolve toward being less virulent; evolution simply selects those that excel at multiplying. In the case of COVID-19, in which the vast majority of transmission occurs before disease becomes severe, reduced severity may not be directly selected for at all. Just like how transmission is decoupled from disease severity for the SARS-CoV-2 virus, it is also true that the new variants have not evolved from the existing ones.
“Thus far, new variants of concern have not evolved from the dominant preceding one. Instead, they have emerged from separate lineages”
By Gajera International School, Utran