CORONAVIRUS

What are the most common covid-19 strains in the US?

The coronavirus has mutated into a number of different variants over the past year, some of which are particularly transmissable, hard to detect or deadly.

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What are the most common covid-19 strains in the US?
ADRIAN DENNIS AFP

The Centers for Disease Control and Prevention (CDC) has identified the UK variant as the most common strain of covid-19 circulating in the United States, one of a number of regionalised variants that have spread globally.

As the coronavirus spreads from person to person it can undergo modifications which alter the genetic make-up, and can potentially make it more transmissible, harder to detect and more deadly. The UK variant, known as B.1.1.7, is thought to spread more easily, be more deadly than other strains and has now spread across the world.

In April CDC Director Dr Rachelle Walensky described the UK variant as “now the most common lineage circulating in the United States.”

She added: ““Testing remains an important strategy to rapidly identify and isolate infectious individuals, including those with variants of concern.”

Why can covid-19 variants be more dangerous?

Unfortunately the B.1.1.7 variant is one of many to have been recorded in the US, and one of a number to have made a significant in-road into the population. Viruses are constantly mutating and changing as the pass between hosts and the new variations often die out fairly quickly.

However sometimes the virus changes in a way that makes it more transmissible and that strain is able to become more prolific than the original strain. Other mutations may make the virus more deadly or reduce the effectiveness of pharmaceuticals like vaccines.

The CDC explains: “If you think about a virus like a tree growing and branching out; each branch on the tree is slightly different than the others. By comparing the branches, scientists can label them according to the differences. These small differences, or variants, have been studied and identified since the beginning of the pandemic.”

What other covid-19 variants are there in the US?

The CDC is constantly tracking and testing the various strains of coronavirus in the US and studies how they are progressing. Although the latest data shows that the most common strain is B.1.1.7, which was first detected in the US in December 2020, there are a number of other prominent variants.

These four are also classified as “variants of concern” by the CDC:

  • B.1.351 – This strain was first detected in South Africa in December 2020, and first appeared in the US in late January.
  • P.1 – First identified in travellers from Brazil during routine testing at a Japanese airport, P.1 was first detected in early January 2021. It was first detected in the US later that month.
  • B.1.427 and B.1.429 - These two variants appear to have originated in the US, having been first detected in California in February 2021.