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Alpha, Delta, Mu: What Are Covid Variants, Exactly?

Everyone is talking about the Delta variant of Covid. It’s all over the news, social media and likely what you’re talking to your neighbors and other community members about. We’ve gotten so used to new scientific jargon that it can feel a little like we’ve all gotten a crash course in virology over the past 18 months. But let’s break it down and go a little more in depth on what, exactly, variants are, why we should care about them and how they are changing the course of the pandemic.

Let’s start at the beginning. What is a variant? A virus has one goal: existence. A virus continues to exist by transmitting itself from vector to vector. In the case of Covid, that’s us. The virus continually adapts to find the easiest and most effective way to continue to exist. Differences noted from the initial virus, called a “wild type” virus, are called variants. Variants continue to develop when the virus is allowed a suitable environment to continue existing. 

Do we need to care about all variants? Sort of. Scientists are able to track the evolution of viruses by noting small changes to the virus itself. These can be anything from changes to the proteins on the surface of the virus, which bear no clinical significance, to real-world changes that affect transmission and infectivity, as we are noting with Delta. 

The Mu variant  is currently classified as a “variant of interest” by the World Health Organization (WHO) and is being watched closely.  Currently, this variant makes up an extremely small percentage of cases in the United States, but Delta became the dominant strain in the U.S. over only a few months, so this doesn’t necessarily mean we are out of the woods. All variants, Mu included, are being watched for “vaccine evasion” — the ability to work around our current vaccines.

In short, stay tuned. 

Scientists call variants with an impact on transmission, evasion of vaccine or treatment and evolution of disease and symptoms “variants of concern.” That brings us to Delta.

Delta is a variant that can be considered a variant of concern because it has increased transmission rates and has managed to cause breakthrough infections in vaccinated individuals. From a viral perspective, Delta has adapted to a more efficient version than the wild type virus as it can infect about double the number of individuals versus the original virus, because it produces a much higher viral load, or copies of the virus, lending to its easy transmission. 

Delta will not be our last variant. In fact, we will continue to see new variants develop until we make ourselves inefficient hosts. How do we do that? By getting enough people with antibodies against Covid so that transmission of the virus is much harder. This will occur one of two ways: We have enough vaccinated people or enough people have developed antibodies through “natural immunity” from having had Covid.

While Covid will always exist, we will get to a point where it will have a much less significant impact on society and our healthcare systems, and this will happen when one or both of the above scenarios have occurred. In short, there needs to be very few remaining hosts. 

In Massachusetts we have done very well with our vaccination rate, so we have a lot to be proud of. However, with areas of the country and world with very low vaccination rates, variants will continue developing and will continue to find their way to any available host. 

Don’t let it be you! If you haven’t already done so, get your vaccine!

Find Vaccine Locations Near Tewksbury.


Nicole Burgett-Yandow, NP has a Masters Degree in Nursing with over 19 years of health care experience. Currently, she practices at Winchester Hospital Center for Weight Management as well as providing after hours on call coverage for patients within the Atrius system. She has worked in a variety of settings including primary care and infectious disease. She has been a Tewksbury resident since 2009 and has two kids in the Tewksbury Public Schools.

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