Why Omicron Will Be The Last COVID Variant of (Major) Concern
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By Amy Rogers, MD, PhD
In my last post I said, “I’m not worried about another, more contagious variant emerging. Omicron is that variant.” I further argued that we were on the verge of achieving a type of herd immunity in the US.
Several people asked a good question about my rosy prediction. In an interconnected world with dismal vaccination rates in many poor countries, won’t future variants continue to emerge? Don’t we first have to distribute effective vaccines to everyone? Doesn’t herd immunity have to be global?
The answer (as with so many things) is both yes and no.
What is a variant?
Every time a living thing reproduces, it copies its genetic material (either DNA or RNA). When DNA or RNA is copied, mistakes can happen. Those mistakes are called mutations, and they are the source of variation in all living things. Because viruses reproduce so quickly and in such great numbers, mutated versions of the virus, which we call variants, are being born all the time.
Because mutations are random, most of them are either harmful or irrelevant to the virus. So most new variants either die immediately or get diluted into obscurity. Rarely, mutations are helpful in some way to the virus’s ability to reproduce. If a set of mutations accumulate that give the virus an advantage over previous versions, then it might start to succeed-and get noticed. (The CDC has a nice, short video using branches of a tree to help describe what variants are. Watch it here.)
Scientists monitor coronavirus variants by sequencing viral RNA from infected people. When a new variant is identified, they analyze the location and nature of the mutations and make their best guess whether the variant is one to worry about, or not. In increasing order, they label the degree of worry as: variant being monitored; variant of interest; variant of concern; and variant of high consequence. ( Source: CDC; click for details of what distinguishes each category)
The omicron variant of SARS-CoV-2 is a variant of concern because it is more transmissible-that is, it’s highly contagious compared to other versions of the virus.
