A New, More Contagious COVID Strain?

“Nations around the world are stopping flights from England to prevent the spread of a new strain of COVID that is 70% more contagious.”

Have you heard headlines like this in the past few day? I sure have.

I’ve got very mixed feelings about commenting on this, because maybe this will scare some public officials into doing what they should have done two months ago. Perhaps it will convince the people out there planning to visit their parents for Christmas that they should change their plans. Or it might shake the confidence of the horrifically irresponsible leaders of Grace Community Church in L.A. or Awaken Church in San Diego to start taking precautions.

So, reluctantly, I’m writing this post to urge everyone to look at this development from a scientific point of view and not to panic. I still believe that evaluating things from that point of view is always the best course.

First, a bit of terminology. My primary sources for this are a paper from the National Institute of Health on viral terminology and This Week in Virology (TWIV), Episode 696. Much of the media uses “variant” and “strain” interchangeable. This has the unfortunate effect of magnifying the effect of every viral mutation that a reporter discusses, leading to conclusions that aren’t backed up by data.

Terminology is important because viruses mutate regularly, including the coronavirus, which has already mutated hundreds of thousands of times. Most of these mutations are meaningless, since they don’t change the way the virus interacts with a host, and they don’t improve genetic fitness. They die out. As the NIH paper points out, “A virus-infected cell will, after only one round or replication, already contain a population of genomes, and virions derived from these genomes will vary slightly from each other.”

What has been discovered in England that is making the rounds in the press is a variant, not a strain. Again, from the NIH paper, “A strain is therefore a genetically stable virus variant that differs from a natural reference virus (type variant) in that it causes a significantly different, observable, phenotype of infection (different kind of disease, infecting a different kind of host, being transmitted by different means etc.).”

So far, the data collected do not support the statement that the variant circulating through south and east England is a strain. The media is speculating that this strain variant is up to 70% more contagious than the coronavirus circulating through England two months ago. They don’t know that, and virologists don’t know it yet either. They have noted two facts: 1. infections in that area have gone up by around 70%. 2. Most of these infections are from the new variant of COVID. Definitely a correlation. But causation? Not necessarily.

Here’s another possibility that was brought up in the TWIV video. It is possible that a certain variant gained a foothold through one or more superspreading events in southern and eastern England, and that the surge in cases there is not a reflection of the variant. Instead it may reflect the same behavior we’re seeing all over the U.S., i.e., people not wearing masks and deciding it’s OK for them to “take a chance” on indoor activities with people not in their household.

Of course, all this does not preclude the possibility of an actual new strain, as opposed to just a variant, developing and being identified as that. We’re just not there yet, as every honest news article on this subject eventually gets around to admitting.

While alarmist headlines over a “new strain” of super-contagious coronavirus make good clickbait, they distract from the main message everyone needs to understand: SARS-CoV-2 is plenty dangerous as it is, and it is contagious enough to flood our hospitals and ICU’s. It is also deadly enough as it is – 325,000 people in the U.S. as of today, increasing at the rate of more than 50,000 people a month.


The best course of action for the immediate future is also unchanged: wear your mask, don’t travel, keep socially distant, wash your hands, and when you can be vaccinated, do it!

Update: here’s an excellent presentation by Vincent Racaniello about this whole subject. Bottom line: at this point, he sees no need for special concern. The value of this is that it’s a very thorough, but understandable, analysis from one of the world’s leading virologists.


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