What to Know about the Fast-Spreading Delta Variant
A highly contagious form of the coronavirus known as the Delta variant is spreading rapidly and becoming increasingly prevalent around the world. First identified in India in December, Delta has now been identified in 111 countries.
In the United States, the variant now accounts for 83% of sequenced COVID-19 cases, said Rochelle Walensky, director of the Centers for Disease Control and Prevention, at a July 20 Senate hearing. In May, Delta was responsible for just 3% of U.S. cases. The World Health Organization projects that Delta will become the dominant variant globally over the coming months.
So, how worried should you be about the Delta variant? We asked experts some common questions about Delta.
What is a variant?
To understand Delta, it's helpful to first understand what a variant is. When a virus infects a person, it gets into your cells and makes a copy of its genome so it can replicate and spread throughout your body.
In the process of making new copies of itself, the virus can make a mistake in its genetic code. Because viruses are replicating all the time, these mistakes — also called mutations — happen pretty often. A new variant emerges when a virus acquires one or more new mutations and starts spreading within a population.
There are thousands of SARS-CoV-2 variants, but most of them don't substantially change the way the virus behaves. The variants that scientists are most interested in are known as variants of concern. These are versions of the virus with mutations that allow the virus to spread more easily, evade vaccines, or cause more severe disease.
"The vast majority of the mutations that have accumulated in SARS-CoV-2 don't change the biology as far as we're concerned," said Jennifer Surtees, a biochemist at the University of Buffalo who's studying the coronavirus. "But there have been a handful of key mutations and combinations of mutations that have led to what we're now calling variants of concern."
One of those variants of concern is Delta, which is now driving many new COVID-19 infections.
Why is the Delta variant so concerning?
"The reason why the Delta variant is concerning is because it's causing an increase in transmission," said Alba Grifoni, an infectious disease researcher at the La Jolla Institute for Immunology. "The virus is spreading faster and people — particularly those who are not vaccinated yet — are more prone to exposure."
The Delta variant has a few key mutations that make it better at attaching to our cells and evading the neutralizing antibodies in our immune system. These mutations have changed the virus enough to make it more than twice as contagious as the original SARS-CoV-2 virus that emerged in Wuhan and about 50% more contagious than the Alpha variant, previously known as B.1.1.7, or the U.K. variant.
These mutations were previously seen in other variants on their own, but it's their combination that makes Delta so much more infectious.
Do vaccines work against the Delta variant?
The good news is, the COVID-19 vaccines made by AstraZeneca, Johnson & Johnson, Moderna, and Pfizer still work against the Delta variant. They remain more than 90% effective at preventing hospitalizations and death due to Delta. While they're slightly less protective against disease symptoms, they're still very effective at preventing severe illness caused by the Delta variant.
"They're not as good as they were against the prior strains, but they're holding up pretty well," said Eric Topol, a physician and director of the Scripps Translational Research Institute, during a July 19 briefing for journalists.
Because Delta is better at evading our immune systems, it's likely causing more breakthrough infections — COVID-19 cases in people who are vaccinated. However, breakthrough infections were expected before the Delta variant became widespread. No vaccine is 100% effective, so breakthrough infections can happen with other vaccines as well. Experts say the COVID-19 vaccines are still working as expected, even if breakthrough infections occur. The majority of these infections are asymptomatic or cause only mild symptoms.
Should vaccinated people worry about the Delta variant?
Vaccines train our immune systems to protect us against infection. They do this by spurring the production of antibodies, which stick around in our bodies to help fight off a particular pathogen in case we ever come into contact with it.
But even if the new Delta variant slips past our neutralizing antibodies, there's another component of our immune system that can help overtake the virus: T cells. Studies are showing that the COVID-19 vaccines also galvanize T cells, which help limit disease severity in people who have been vaccinated.
"While antibodies block the virus and prevent the virus from infecting cells, T cells are able to attack cells that have already been infected," Grifoni said. In other words, T cells can prevent the infection from spreading to more places in the body. A study published July 1 by Grifoni and her colleagues found that T cells were still able to recognize mutated forms of the virus — further evidence that our current vaccines are effective against Delta.
Can fully vaccinated people spread the Delta variant?
Previously, scientists believed it was unlikely for fully vaccinated individuals with asymptomatic infections to spread Covid-19. But the Delta variant causes the virus to make so many more copies of itself inside the body, and high viral loads have been found in the respiratory tracts of people who are fully vaccinated. This suggests that vaccinated people may be able to spread the Delta variant to some degree.
If you have COVID-19 symptoms, even if you're fully vaccinated, you should get tested and isolate from friends and family because you could spread the virus.
What risk does Delta pose to unvaccinated people?
The Delta variant is behind a surge in cases in communities with low vaccination rates, and unvaccinated Americans currently account for 97% of hospitalizations due to COVID-19, according to Walensky. The best thing you can do right now to prevent yourself from getting sick is to get vaccinated.
Gigi Gronvall, an immunologist and senior scholar at the Johns Hopkins Center for Health Security, said in this week's "Making Sense of Science" podcast that it's especially important to get all required doses of the vaccine in order to have the best protection against the Delta variant. "Even if it's been more than the allotted time that you were told to come back and get the second, there's no time like the present," she said.
With more than 3.6 billion COVID-19 doses administered globally, the vaccines have been shown to be incredibly safe. Serious adverse effects are rare, although scientists continue to monitor for them.
Being vaccinated also helps prevent the emergence of new and potentially more dangerous variants. Viruses need to infect people in order to replicate, and variants emerge because the virus continues to infect more people. More infections create more opportunities for the virus to acquire new mutations.
Surtees and others worry about a scenario in which a new variant emerges that's even more transmissible or resistant to vaccines. "This is our window of opportunity to try to get as many people vaccinated as possible and get people protected so that so that the virus doesn't evolve to be even better at infecting people," she said.
Does Delta cause more severe disease?
While hospitalizations and deaths from COVID-19 are increasing again, it's not yet clear whether Delta causes more severe illness than previous strains.
How can we protect unvaccinated children from the Delta variant?
With children 12 and under not yet eligible for the COVID-19 vaccine, kids are especially vulnerable to the Delta variant. One way to protect unvaccinated children is for parents and other close family members to get vaccinated.
It's also a good idea to keep masks handy when going out in public places. Due to risk Delta poses, the American Academy of Pediatrics issued new guidelines July 19 recommending that all staff and students over age 2 wear face masks in school this fall, even if they have been vaccinated.
Parents should also avoid taking their unvaccinated children to crowded, indoor locations and make sure their kids are practicing good hand-washing hygiene. For children younger than 2, limit visits with friends and family members who are unvaccinated or whose vaccination status is unknown and keep up social distancing practices while in public.
While there's no evidence yet that Delta increases disease severity in children, parents should be mindful that in some rare cases, kids can get a severe form of the disease.
"We're seeing more children getting sick and we're seeing some of them get very sick," Surtees said. "Those children can then pass on the virus to other individuals, including people who are immunocompromised or unvaccinated."
Chicken that is grown entirely in a laboratory, without harming a single bird, could be sold in supermarkets in the coming months. But critics say the doubts about lab-grown meat have not been appropriately explored.
Last November, when the U.S. Food and Drug Administration disclosed that chicken from a California firm called UPSIDE Foods did not raise safety concerns, it drily upended how humans have obtained animal protein for thousands of generations.
“The FDA is ready to work with additional firms developing cultured animal cell food and production processes to ensure their food is safe and lawful,” the agency said in a statement at the time.
Assuming UPSIDE obtains clearances from the U.S. Department of Agriculture, its chicken – grown entirely in a laboratory without harming a single bird – could be sold in supermarkets in the coming months.
“Ultimately, we want our products to be available everywhere meat is sold, including retail and food service channels,” a company spokesperson said. The upscale French restaurant Atelier Crenn in San Francisco will have UPSIDE chicken on its menu once it is approved, she added.
Known as lab-grown or cultured meat, a product such as UPSIDE’s is created using stem cells and other tissue obtained from a chicken, cow or other livestock. Those cells are then multiplied in a nutrient-dense environment, usually in conjunction with a “scaffold” of plant-based materials or gelatin to give them a familiar form, such as a chicken breast or a ribeye steak. A Dutch company called Mosa Meat claims it can produce 80,000 hamburgers derived from a cluster of tissue the size of a sesame seed.
Critics say the doubts about lab-grown meat and the possibility it could merge “Brave New World” with “The Jungle” and “Soylent Green” have not been appropriately explored.
That’s a far cry from when it took months of work to create the first lab-grown hamburger a decade ago. That minuscule patty – which did not contain any fat and was literally plucked from a Petri dish to go into a frying pan – cost about $325,000 to produce.
Just a decade later, an Israeli company called Future Meat said it can produce lab-grown meat for about $1.70 per pound. It plans to open a production facility in the U.S. sometime in 2023 and distribute its products under the brand name “Believer.”
Costs for production have sunk so low that researchers at Carnegie Mellon University in Pittsburgh expect sometime in early 2024 to produce lab-grown Wagyu steak to showcase the viability of growing high-end cuts of beef cheaply. The Carnegie Mellon team is producing its Wagyu using a consumer 3-D printer bought secondhand on eBay and modified to print the highly marbled flesh using a method developed by the university. The device costs $200 – about the same as a pound of Wagyu in the U.S. The initiative’s modest five-figure budget was successfully crowdfunded last year.
“The big cost is going to be the cells (which are being extracted by a cow somewhere in Pennsylvania), but otherwise printing doesn’t add much to the process,” said Rosalyn Abbott, a Carnegie Mellon assistant professor of bioengineering who is co-leader on the project. “But it adds value, unlike doing this with ground meat.”
Lab-Grown Meat’s Promise
Proponents of lab-grown meat say it will cut down on traditional agriculture, which has been a leading contributor to deforestation, water shortages and contaminated waterways from animal waste, as well as climate change.
An Oxford University study from 2011 concludes lab-grown meat could have greenhouse emissions 96 percent lower compared to traditionally raised livestock. Moreover, proponents of lab-grown meat claim that the suffering of animals would decline dramatically, as they would no longer need to be warehoused and slaughtered. A recently opened 26-story high-rise in China dedicated to the raising and slaughtering of pigs illustrates the current plight of livestock in stark terms.
Scientists may even learn how to tweak lab-grown meat to make it more nutritious. Natural red meat is high in saturated fat and, if it’s eaten too often, can lead to chronic diseases. In lab versions, the saturated fat could be swapped for healthier, omega-3 fatty acids.
But critics say the doubts about lab-grown meat and the possibility it could merge “Brave New World” with “The Jungle” and “Soylent Green” have not been appropriately explored.
A Slippery Slope?
Some academics who have studied the moral and ethical issues surrounding lab-grown meat believe it will have a tough path ahead gaining acceptance by consumers. Should it actually succeed in gaining acceptance, many ethical questions must be answered.
“People might be interested” in lab-grown meat, perhaps as a curiosity, said Carlos Alvaro, an associate professor of philosophy at the New York City College of Technology, part of the City University of New York. But the allure of traditionally sourced meat has been baked – or perhaps grilled – into people’s minds for so long that they may not want to make the switch. Plant-based meat provides a recent example of the uphill battle involved in changing old food habits, with Beyond Meat’s stock prices dipping nearly 80 percent in 2022.
"There are many studies showing that people don’t really care about the environment (to that extent)," Alvaro said. "So I don’t know how you would convince people to do this because of the environment.”
“From my research, I understand that the taste (of lab-grown meat) is not quite there,” Alvaro said, noting that the amino acids, sugars and other nutrients required to grow cultivated meat do not mimic what livestock are fed. He also observed that the multiplication of cells as part of the process “really mimic cancer cells” in the way they grow, another off-putting thought for would-be consumers of the product.
Alvaro is also convinced the public will not buy into any argument that lab-grown meat is more environmentally friendly.
“If people care about the environment, they either try and consume considerably less meat and other animal products, or they go vegan or vegetarian,” he said. “But there are many studies showing that people don’t really care about the environment (to that extent). So I don’t know how you would convince people to do this because of the environment.”
Ben Bramble, a professor at Australian National University who previously held posts at Princeton and Trinity College in Ireland, takes a slightly different tack. He noted that “if lab-grown meat becomes cheaper, healthier, or tastier than regular meat, there will be a large market for it. If it becomes all of these things, it will dominate the market.”
However, Bramble has misgivings about that occurring. He believes a smooth transition from traditionally sourced meat to a lab-grown version would allow humans to elide over the decades of animal cruelty perpetrated by large-scale agriculture, without fully reckoning with and learning from this injustice.
“My fear is that if we all switch over to lab-grown meat because it has become cheaper, healthier, or tastier than regular meat, we might never come to realize what we have done, and the terrible things we are capable of,” he said. “This would be a catastrophe.”
Bramble’s writings about cultured meat also raise some serious moral conundrums. If, for example, animal meat may be cultivated without killing animals, why not create products from human protein?
Actually, that’s already happened.
It occurred in 2019, when Orkan Telhan, a professor of fine arts at the University of Pennsylvania, collaborated with two scientists to create an art exhibit at the Philadelphia Museum of Art on the future of foodstuffs.
Although the exhibit included bioengineered bread and genetically modified salmon, it was an installation called “Ouroboros Steak” that drew the most attention. That was comprised of pieces of human flesh grown in a lab from cultivated cells and expired blood products obtained from online sources.
The exhibit was presented as four tiny morsels of red meat – shaped in patterns suggesting an ouroboros, a dragon eating its own tail. They were placed in tiny individual saucers atop a larger plate and placemat with a calico pattern, suggesting an item to order in a diner. The artwork drew international headlines – as well as condemnation for Telhan’s vision.
Telhan’s artwork is intended to critique the overarching assumption that lab-grown meat will eventually replace more traditional production methods, as well as the lack of transparency surrounding many processed foodstuffs. “They think that this problem (from industrial-scale agriculture) is going be solved by this new technology,” Telhan said. “I am critical (of) that perspective.”
Unlike Bramble, Telhan is not against lab-grown meat, so long as its producers are transparent about the sourcing of materials and its cultivation. But he believes that large-scale agricultural meat production – which dates back centuries – is not going to be replaced so quickly.
“We see this again and again with different industries, like algae-based fuels. A lot of companies were excited about this, and promoted it,” Telhan said. “And years later, we know these fuels work. But to be able to displace the oil industry means building the infrastructure to scale takes billions of dollars, and nobody has the patience or money to do it.”
Alvaro concurred on this point, which he believes is already weakened because a large swath of consumers aren’t concerned about environmental degradation.
“They’re going to have to sell this big, but in order to convince people to do so, they have to convince them to eat this product instead of regular meat,” Alvaro said.
Hidden Tweaks?
Moreover, if lab-based meat does obtain a significant market share, Telhan suggested companies may do things to the product – such as to genetically modify it to become more profitable – and never notify consumers. That is a particular concern in the U.S., where regulations regarding such modifications are vastly more relaxed than in the European Union.
“I think that they have really good objectives, and they aspire to good objectives,” Telhan said. “But the system itself doesn't really allow for that much transparency.”
No matter what the future holds, sometime next year Carnegie Mellon is expected to hold a press conference announcing it has produced a cut of the world’s most expensive beef with the help of a modified piece of consumer electronics. It will likely take place at around the same time UPSIDE chicken will be available for purchase in supermarkets and restaurants, pending the USDA’s approvals.
Abbott, the Carnegie Mellon professor, suggested the future event will be both informative and celebratory.
“I think Carnegie Mellon would have someone potentially cook it for us,” she said. “Like have a really good chef in New York City do it.”
In this week's Friday Five, breathing this way may cut down on anxiety, a fasting regimen that could make you sick, this type of job makes men more virile, 3D printed hearts could save your life, and the role of metformin in preventing dementia.
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
Here are the promising studies covered in this week's Friday Five, featuring interviews with Dr. David Spiegel, associate chair of psychiatry and behavioral sciences at Stanford, and Dr. Filip Swirski, professor of medicine and cardiology at the Icahn School of Medicine at Mount Sinai.
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Here are the promising studies covered in this week's Friday Five, featuring interviews with Dr. David Spiegel, associate chair of psychiatry and behavioral sciences at Stanford, and Dr. Filip Swirski, professor of medicine and cardiology at the Icahn School of Medicine at Mount Sinai.
- Breathing this way cuts down on anxiety*
- Could your fasting regimen make you sick?
- This type of job makes men more virile
- 3D printed hearts could save your life
- Yet another potential benefit of metformin
* This video with Dr. Andrew Huberman of Stanford shows exactly how to do the breathing practice.