What is a variant, how does it form, and why is it harmful?
There’s the delta variant, the lambda variant, and even the delta-plus variant. Variants of COVID-19 are spreading in the United States and in many parts of the world.
A variant is a mutated version of a virus that is produced when the virus replicates — when it is transmitted.
But how exactly do variants form and why should we be concerned about them?
Lisa M. Lee, who is associate vice president for scholarly integrity and research compliance, and professor of public health at Virginia Tech, has some answers. Lee is an epidemiologist, a bioethicist, and an ethics educator. For more than 25 years, she has worked in public health and ethics, including 14 years at the Centers for Disease Control and Prevention.
Q. How does a variant form?
Lee: Variants develop when a virus is transmitted. Every time it reproduces in a new host, a virus has an opportunity to mutate, to reproduce incorrectly. Most of the mutations are harmless, but sometimes the change will result in a stronger or more contagious version of a virus. And when that happens, it hurts us.
We saw variants develop very quickly with SARS-CoV-2 [the virus that causes COVID-19]. That was a real concern for epidemiologists because it meant that the virus could mutate quickly. We recognized that if we did not get this under control in short order, we were going to end up with more virulent strains that would spread faster or against which our current vaccines would not work.
Q. Why is the delta variant considered more contagious than the original COVID-19 virus?
Lee: There are estimates that the delta variant is 60 percent more contagious. Studies have found that with the delta variant there are a thousand times more viral particles in the nasal passage than with the original virus.
That means there are many more viral particles being pushed out when we breathe. The recipient inhales a bigger viral load and is much more likely to become infected.
When the delta variant is transmitted, there are many more viral particles that hang on, so it is stickier. All viruses are different, but what makes the delta variant concerning is that it is more likely to attach and get inside the recipient’s cells.
Q. How do we stop these variants from forming and spreading?
Lee: The answer for reducing the development of variants is to stop transmitting the virus. If we intervene with the vaccine and reduce the likelihood that the virus stays around, we can reduce the chance that dangerous variants develop.
The great promise of the vaccine was that we would stop transmitting the virus, which would reduce the development of variants. Because we have not achieved the vaccine coverage we need to extinguish transmission — at least 85 percent of the entire globe — we continue to see dangerous variants develop.
This is why, even if someone thinks that they don’t need a vaccine for themselves, everyone who can be vaccinated should be vaccinated. Unvaccinated people unwittingly serve as the reservoir that allows this virus to continue to be transmitted and as a result, continue to mutate.
Vaccination is of course to protect individuals, but more than that, vaccination is for all of us as a community. For all the people who cannot get vaccinated because they are under 12 years old and for all of the people with other medical conditions that make the vaccine less effective, that is who to get vaccinated for. If all of the rest of us are vaccinated, we help protect those in our community who cannot be.
Q. Herd immunity occurs when the majority of a population has received a vaccine. How can herd immunity help stop the spread of variants?
Lee: Herd immunity is like a donut. People who cannot be vaccinated for various reasons are the middle, and the donut around them are all people who have been vaccinated, providing a layer of protection from the virus.
When a person with the virus interacts with the donut — think of throwing on a candy sprinkle — it cannot get through the vaccinated donut and cannot infect the vulnerable people inside the donut hole.
Because now we have these super-contagious variants, we are going to need an even higher level of population vaccination. The quicker we can do that, the more quickly we will prevent transmission and stop these variants.
Q. If someone is infected with SARS-CoV-2, do they likely have the delta variant?
Lee: When the delta variant was introduced into the U.S. in early May 2021, it started somewhere with a couple of transmissions. Then, because it is so much more infectious, it soon started to outperform the original virus. By August the delta variant became the dominant virus transmitted in most communities.
The way we know which variants are where is to do public health surveillance, which is to actually test the specimens that people give for diagnosis and type them in a laboratory.
CDC has a public health surveillance program that identifies variants and can tell us the proportion of which variant is being transmitted in the population. Currently, the delta variant accounts for almost 95 percent of COVID-19 infections in the U.S.
Q. Will there be more variants to develop from COVID-19?
Lee: I am certain that we will continue to see new variants as long as the virus continues to be transmitted. Until 85 percent of the world’s population is vaccinated, the virus will mutate and produce variants. That is the unfortunate reality of viral replication. Our best hope for returning to something closer to pre-COVID life is swift vaccination of all communities.
Story by Jenny Kincaid Boone