Science and Action about the Covid-19 Delta Variant
Photo credits: Fusion Medical Animation
Update January 2022:
While this article was written in August 2021 to explain the rise of the Delta variant, the biological mechanisms described here are relevant to any viral variant. While Omicron seems to cause less severe disease, it is still crucial to get vaccinated, mask, test, and social distance. Check out the links below for reliable sources of health information.
TL; DR: To stop the rise of the Delta variant and to prevent future COVID-19 variants, we must smash the virus’s global supply chain. We can do this with masks, vaccinations, and reputable health information, all around the world.
My news feed is brimming with reports about the Delta variant of SARS-CoV-2, the coronavirus that causes COVID-19. I bet yours is too, no matter where you call home. What’s the deal with Delta? How worried should we be? And what should we do about it?
To understand the situation, let’s go back to biology basics for a moment. Evolution is the process that delivers the amazing diversity of life here on Earth. Its raw material is variation, which at the level of DNA (or RNA) is called “mutation”. Imagine a DNA sequence like ATCGA. If that T gets accidentally changed to another DNA base like C, then that new “C” is a mutation. Outside the world of comic books, “mutation” doesn’t necessarily mean “bad”—it just means “different” from what was there in the previous generation.
In other words, mutation is a feature of evolution—not a bug.
Evolution optimizes an organism for “fitness”, or the ability to leave offspring. That relentless optimization is underpinning the waves of SARS-CoV-2 variants that have been sweeping the globe since the pandemic’s earliest days. As each virus makes millions of new viruses using the host cell’s machinery, errors creep in, creating variations as it copies its source code (RNA in the case of SARS-CoV-2). Thanks to genome sequencing technologies, we can identify those new mutations and the viral variants carrying them. You can see that in action here.
💡 The rise of variants is simply a numbers game. More viruses out there making copies of themselves lead to more mutations; more mutations lead to more chances that one mutation (or more) will confer an advantage in spreading to new hosts like you and me... who then unwittingly manufacture millions more virus particles.
Any of the steps by which a virus infects a host, makes more viruses, and spreads to new hosts can be impacted by a mutation in the virus’s source code. This process continues as long as there are infections; expect to hear more about the Lambda variant in the coming days.
Ready for some molecular science? The Delta variant carries a bunch of mutations. Three of them are in a part of the virus called the receptor binding domain (RBD), and they make it easier for the RBD to grab onto the human’s natural ACE2 receptor and use it as a molecular door into the human cell. These mutations seem to make it easier for Delta to evade our immune system, as do some other mutations in the spike protein. Delta also carries a mutation in its “furin cleavage site” that makes it easier for the virus to get into the human cell. Each of these mutations (and a few others) gives Delta an advantage over other SARS-CoV-2 variants, which is helping it take over all around the world.
By “advantage” I mean an evolutionary advantage to the virus, of course. If those changes make it harder for the virus to make more copies of itself, then those mutations will be selected against and will not spread. But if those changes make it easier for the virus to make more viruses, then they spread, and the evolutionary numbers game continues.
To humans, these viral advantages can translate to things like us being easier to infect, being more infectious to the people around us, or becoming sicker if we do get infected. Fortunately, based on the data we have today, it seems that Delta is not making vaccinated people sicker than other virus variants like Alpha.
The key word in that last sentence is "vaccinated”.
Unfortunately, Delta spreads more easily than other variants and the viral load (number of viral particles) in Delta-infected people is higher than in people infected with other variants. This combination is bad news for people who are unvaccinated, because early data are suggesting that unvaccinated people may be twice as likely to be hospitalized with severe disease if they’ve caught Delta rather than Alpha.
And around the world, the Delta variant is becoming more widespread every day.
It’s important to note that while vaccination is not a perfect defense against Delta, it is by far our most powerful weapon. Here in the USA, states with higher vaccination rates are seeing lower rates of hospitalization. It looks like many of the currently authorized vaccines are pretty effective against severe disease from Delta. And based on early data, it looks like “breakthrough” Delta infections of vaccinated people are usually asymptomatic or mild. Two great pieces of news for vaccinated people, right?
Vaccination is not a perfect defense, but us by far our most powerful weapon.
But what if you’re vaccinated and you don’t know that you have COVID-19 because you don’t feel too sick? Could you accidentally spread Delta? The answer seems to be yes, based on a very recent study showing that in the (fairly rare) case of a vaccinated person getting infected with Delta, their viral load can be similar to the viral load in an unvaccinated person. Accurate rapid at-home antigen tests could help with this accidental transmission—but most of us don’t have access to such tests.
💡 Remember, it’s still essential to get vaccinated, because your risk of severe disease—and death—go way down after vaccination.
Here’s how my family is handling the uncertainty from the spread of the Delta variant. My husband and I are both biologists; we’re both fully dosed with a vaccine authorized in the USA. Our son is not vaccinated because his age group doesn’t qualify yet. Although our county has a pretty high vaccination rate, we continue to wear masks in public (both indoors and outdoors). When we socialize, we focus on being outdoors and in small groups. We double mask during travel, and we focus on the travel that is most important to us. We answer the many questions from our friends and neighbors and point them to reliable information from experts, health agencies, and trusted news outlets like The New York Times, CNN, and The Economist.
I am eagerly awaiting the day that my son will qualify for his first shot (fingers crossed for early fall). Yes, in general children are far less likely to suffer severe COVID-19 than adults. But my son feels safer with his mask on, including at school, and his willingness to wear his mask makes me feel safer, too. That means I can smile every time he hugs his 83-year-old grandfather.
How can we stop this pandemic from stretching on, giving more and more opportunities for new mutations to arise that favor the virus? We need to allocate more resources to COVID-19 testing and variant sequencing—which should set the stage for monitoring other infectious diseases before they become pandemics.
💡 It is also imperative that we stop the “infodemic” of misinformation and disinformation that has transformed a public health crisis into a catastrophe of social identity and political ideology.
Perhaps most importantly, we must smash this virus’s global supply chain. Everywhere around the world. As fast as possible.
Here’s the bottom line: Viral evolution requires infections. How do we stop infections?
With vaccinations. With smart choices about social gatherings. With masks -yes, even if you’re vaccinated.
With hope. And with science.
We have the tools that we need. Now we need the will to finish off this pandemic.
We are strong together.
About Tiffany
Dr. Tiffany Vora speaks, writes, and advises on how to harness technology to build the best possible future(s). She is an expert in biotech, health, & innovation.
For a full list of topics and ways to collaborate, visit Tiffany’s Work Together webpage.
Donate = Impact
After a 19-day voyage to Antarctica aboard The Island Sky in November 2023, Tiffany has many remarkable stories to share & a wealth of insights to catalyze a sustainable future.
You can support her ongoing journey by making a contribution through her donation page. Your support will spread positive impact around the world, empower Tiffany to protect time for impact-focused projects, and support logistical costs for pro bono events with students & nonprofits.