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."
A group of protesters march for science.
You read an online article about climate change, then start scanning the comments on Facebook. Right on cue, Seth the Science Denier chimes in with:
The study found that science deniers whose arguments go unchallenged can harm other people's attitudes toward science.
"Humans didn't cause this. Climate is always changing. The earth has always had cycles of warming and cooling—what's happening now isn't new. The idea that humans are causing something that happened long before humans were even around is absurd."
You know he's wrong. You recognize the fallacy in his argument. Do you take the time to engage with him, or write him off and move along?
New research suggests that countering science deniers like Seth is important—not necessarily to change their minds, but to keep them from influencing others.
Looking at Seth's argument, someone without much of a science background might think it makes sense. After all, climate is always changing. The earth has always gone through cycles, even before humans. Without a scientifically sound response, a reader may begin to doubt that human-caused climate change is really a thing.
A study published in Nature found that science deniers whose arguments go unchallenged can harm other people's attitudes toward science. Many people read discussions without actively engaging themselves, and some may not recognize erroneous information when they see it. Without someone to point out how a denier's statements are false or misleading, people are more likely to be influenced by the denier's arguments.
Researchers tested two strategies for countering science denial—by topic (presenting the facts) and by technique (addressing the illogical argument). Rebutting a science denier with facts and pointing out the fallacies in their arguments both had a positive effect on audience attitudes toward legitimate science. A combination of topic and technique rebuttals also had a positive effect.
"In the light of these findings we recommend that advocates for science train in topic and technique rebuttal," the authors wrote. "Both strategies were equally effective in mitigating the influence of science deniers in public debates. Advocates can choose which strategy they prefer, depending on their levels of expertise and confidence."
Who you're really addressing are the lurkers who might be swayed by misinformation if it isn't countered by real science.
So what does that look like? If we were to counter Seth's statements with a topic rebuttal, focusing on facts, it might look something like this:
Yes, climate has always changed due to varying CO2 levels in the atmosphere. Scientists have tracked that data. But they also have data showing that human activity, such as burning fossil fuels, has dramatically increased CO2 levels. Climate change is now happening at a rate that isn't natural and is dangerous for life as we know it.
A technique rebuttal might focus on how Seth is using selective information and leaving out important facts:
Climate has always changed, that's true. But you've omitted important information about why it changes and what's different about the changes we're seeing now.
Ultimately, we could combine the two techniques in something like this:
Climate has always changed, but you've omitted important information about why it changes and what's different about what we're seeing now. Levels of CO2 in the atmosphere are largely what drives natural climate change, but human activity has increased CO2 beyond natural levels. That's making climate change happen faster than it should, with devastating effects for life on Earth.
Remember that the point is not to convince Seth, though it's great if that happens. Who you're really addressing are the lurkers who might be swayed by misinformation if it isn't countered by truth.
It's a wacky world out there, science lovers. Keep on fighting the good fight.
Diagnosed by App: Medical Testing in the Palm of Your Hand
The shift to in-home medical testing through smartphone apps is expected to save patients time in receiving certain kinds of diagnoses, but raises some privacy concerns.
Urinary tract infections aren't life-threatening, but they can be excruciatingly painful and debilitating.
"Overnight, I'd be gripped by this searing pain and I can barely walk," says Ling Koh, a Los Angeles-based bioengineer. But short of going to the ER or urgent care, she'd have to suffer for a few days until she could get in to see her family doctor for an antibiotic prescription.
Smartphones are now able to do on-the-spot diagnostic tests that were previously only able to be performed in a lab.
No longer. Koh, who works for Scanwell Health, was instrumental in the development of the company's smartphone app that is FDA-cleared for urinary tract infection screening. It allows someone to test urine at home using a paper test strip — the same one used by doctors in ERs and labs. The phone app reads a scan card from the test kit that can analyze what's on the strip and then connect the patient to a physician who can make a virtual diagnosis.
Test strips cost $15 for a three-pack and consultation with a doc is about the same as an average co-pay -- $25, and the app matches the quality of clinical laboratory tests, according to the company. Right now, you can get a referral to a telehealth visit with a doctor in California and get a prescription. A national rollout is in the works within the next couple of months.
"It's so easy to use them at home and eliminate the inefficiencies in the process," says Koh. "A telemedicine doctor can look at the test results and prescribe directly to the pharmacy instead of women waiting at home, miserable, and crying in the bathtub."
Scanwell is now involved in an ongoing National Institutes of Health- sponsored study of chronic kidney disease to test a version of the app to identify patients who have the disease, which affects more than 30 million Americans. "Because kidney disease has virtually no symptoms, by the time people realize they're sick, their illness is advanced and they're ready for dialysis," says Koh. "If we can catch it sooner, early intervention can help them avoid kidney failure."
Smartphones have changed society — and now they may change medical care, too. Thanks to the incredible processing capabilities of our smartphones, which come equipped with a camera, access to the internet and are thousands of times faster than the 1960s era NASA computers that ran the Apollo Moon Mission, these pocket-sized powerhouses have become an invaluable tool for managing our health and are even able to do on-the-spot diagnostic tests that were previously only able to be performed in a lab.
This shift to in-home testing is the wave of the future, promising to ease some of the medical care bottlenecks in which patients can have two- to three-week waits to see their family doctors and lift some of the burdens on overworked physicians.
"This is really the democratization of medicine because a lot of the things we used to rely on doctors, hospitals, or labs to do we'll be able to do ourselves," says Dr. Eric Topol, an eminent cardiologist and digital health pioneer at the Scripps Clinic and Research Institute in La Jolla.
But troubling questions remain. Aside from the obvious convenience, are these tests truly as accurate as ones in a doctor's office? And with all this medical information stored and collected by smartphones, will privacy be sacrificed? Will friends, family members, and employers suddenly have access to personal medical information we'd rather keep to ourselves?
The range of what these DIY health care apps can do is mind-boggling, and even more complex tests are on the way.
"I'm really worried about that because we've let our guard down," says Topol. "Data stored on servers is a target for cyber thieves — and data is being breached, hacked, brokered, and sold, and we're complacent."
Still, the apps have come a long way since 2011 when Topol whipped out an experimental smartphone electro-cardiogram that he had been testing on his patients when a fellow passenger on a flight from Washington D.C. was seized with severe chest pains. At 35,000 feet in the air, the app, which uses fingertip sensors to detect heart rate, showed the man was having a heart attack. After an emergency landing, the passenger was rushed to the closest hospital and survived. These days, even the Apple Watch has an FDA-approved app that can monitor your electro-cardiogram readings.
The range of what these DIY health care apps can do is mind-boggling, and even more complex tests are on the way. Phone apps can now monitor sleep quality to detect sleep apnea, blood pressure, weight and temperature. In the future, rapid diagnostic tests for infectious diseases, like flu, Dengue or Zika, and urinalysis will become common.
"There is virtually no limit to the kinds of testing that can be done using a smartphone," says Dr. John Halamka, Executive Director of the Health Technology Exploration Center at Beth Israel Lahey Health. "No one wants to drive to a clinician's office or lab if that same quality testing can be achieved at a lower cost without leaving home."
SkinVision's skin cancer screening tool, for instance, can tell if a suspicious mole is cancerous. Users take three photos, which are then run through the app's algorithm that compares their lesions with more than three million pictures, evaluating such elements as asymmetry, color, and shape, and spits out an assessment within thirty seconds. A team of in-house experts provide a review regardless of whether the mole is high or low risk, and the app encourages users to see their doctors. The Dutch-based company's app has been used by more than a million people globally in the EU, and in New Zealand and Australia, where skin cancer is rampant and early detection can save lives. The company has plans to enter the U.S. market, according to a spokesperson.
Apps like Instant Heart Rate analyze blood flow, which can indicate whether your heart is functioning normally, while uChek examines urine samples for up to 10 markers for conditions like diabetes and urinary tract infections. Some behavioral apps even have sensors that can spot suicide risks if users are less active, indicating they may be suffering from a bout of the blues.
Even more complex tests are in the research pipeline. Apps like ResAppDX could eventually replace x-rays, CT scans, and blood tests in diagnosing severe respiratory infections in kids, while an EU-funded project called i-Prognosis can track a variety of clues — voice changes, facial expressions, hand steadiness — that indicate the onset of Parkinson's disease.
These hand-held testing devices can be especially helpful in developing countries, and there are pilot programs to use smartphone technology to diagnose malaria and HIV infections in remote outposts in Africa.
"In a lot of these places, there's no infrastructure but everyone has a smartphone," says Scanwell's Koh. "We need to leverage the smartphone in a clinically relevant way."
However, patient privacy is an ongoing concern. A 2019 review in the Journal of the American Medical Association conducted by Australian and American researchers looked at three dozen behavioral health apps, mainly for depression and smoking cessation. They found that about 70 percent shared data with third parties, like Facebook and Google, but only one third of them disclosed this in a privacy policy.
"Patients just blindly accept the end user agreements without understanding the implications."
Users need to be vigilant, too. "Patients just blindly accept the end user agreements without understanding the implications," says Hamalka, who is also the Chief Information Officer and Dean for Technology at Harvard Medical School.
And quality control is an issue. Right now, the diagnostic tools currently available have been vetted by the FDA, and overseas companies like Skin Vision have been scrutinized by the U.K.'s National Health Service and the EU. But the danger is that a lot of apps are going to be popping up soon that haven't been properly tested, due to loopholes in the regulations.
"All we want," says Topol, "are rigorous studies to make sure what consumers are using is validated."
[Correction, August 19th, 2019: An earlier version of this story misstated the specifics of SkinVision's service. A team of in-house experts reviews users' submissions, not in-house dermatologists, and the service is not free.]