Viral Variant

A new variant of the SARS-CoV-2 virus is emerging in Great Britain, becoming the dominate form of the virus that causes COVID-19 in London and southeast England.  What are the implications of this new variant?

The new variant has been officially named “SARS-CoV-2 VOC 202012/01.”  You may also see it referred to as “B.1.1.7”, or “SARS-CoV-2 Variant” in both the popular and scientific press.  This variant has a mutation in one of the spike proteins which binds the virus to human cells during the infection process.  So far, this variant has not been reported in the United States.

Viral mutations are common.  In fact, many different strains of the SARS-CoV-2 virus are likely to exist in the United States right now.  But so far, none of these mutations has caused a significant difference in the binding capacity of the virus to human cells.  At least none that we know of.  Our understanding of SARS-CoV-2 continues to evolve rapidly.

The variant identified in England seems to spread more quickly in humans.  The thought is that the change in spike binding protein makes it more likely for the virus to stick to human cells.  

Why does increased stickiness of virus affect the virus’ ability to spread?  After the virus sticks to the cells lining the inside of the nose and upper airways, the virus injects its genetic material into the human cell.  This genetic material is programmed to take over the machinery of the cell, causing it to abandon its usual functions and become a virus producing factory, spewing out hundreds of new copies of the virus.  These new viral copies infect other cells, either in the same body, or in bodies nearby.  This accounts for the waxing of disease within a sick, infected person, and the spread of virus from person-to-person.  If the virus is stickier, more human cells are taken over, and more copies of the virus are produced, making it easier for the virus to go, well, viral!

Will tests detect this new virus strain?  Yes, PCR tests will, at least for now.  Because PCR tests use two or three different detection targets, the change in this variant’s genetic code is not enough to evade detection by PCR tests.  However, as the genetic code of the virus continues to evolve, it is conceivable that a mutation will arise that is not detected by tests currently in use, even PCR tests.  Antigen tests, which already have low sensitivity, do not share the multi-targeted feature of PCR tests; therefore, even more false negative antigen test results can be expected when the variant becomes more prevalent.

Will the variant reduce the effectiveness of vaccine?  The honest answer is that we really don’t know.  Theoretically, this variant will not, since the vaccines released in the U.S. are polyclonal, causing the formation of antibodies to several different parts of the virus’ spike proteins.  The theory is that even if one part of the spike protein changes, the antibodies will still be effective against the other parts that have not changed.  But theory and reality are not the same thing.  We won’t know for sure until vaccine effectiveness has been studied in populations infected by the variant.  

This brings us to one final point about this viral variant.  This variant is undoubtedly the first of many variants to come, and the answers for these yet-to-be-seen variants may be different than the answers for this one.  Viruses want to survive.  Just as the use of antibiotics causes the emergence of antibiotic resistance in bacteria, the use of vaccine will favor viral mutations that evade vaccine-induced immunity.   Variants will emerge that are unaffected by vaccine.

The pandemic is a war, both metaphorically and really.  Our best defense is the practice of what we know reduces spread: mask up, keep apart, and isolate when exposed.  We will prevail.  But it’s still too early to celebrate victory.