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Dec 24, 2021 · Omicron is less severe. ... It spreads faster than other variants and can bypass some of the immune protection from vaccines and prior infections. ... Protection against severe disease is likely ...
Jan 7, 2022 · Overall, whatever the mechanism, the evidence that omicron is causing less severe disease than previous variants is now adding up. But this doesn’t mean we should see it as less of a threat.
Sep 1, 2023 · The second question has been whether Omicron and its subvariants are more likely than their predecessors to cause severe disease. So far, Omicron strains have tended to be mostly mild, causing a runny nose, sore throat, and other cold-like symptoms, as opposed to lower respiratory tract symptoms. Experts say that the summer uptick in cases and ...
- kathy.katella-cofrancesco@yale.edu
- Overview
- Is Omicron really causing less severe disease than Delta?
- Does severity differ based on age or preexisting conditions?
- Why is Omicron dangerous if it’s less severe than Delta?
- What do these changes mean for at-home testing?
- Does double masking help protect against Omicron?
- Do we still need to disinfect surfaces, stand further away from each other, or alter any other aspect of personal hygiene?
- Is long COVID still a risk when it comes to Omicron?
This variant is more transmissible. So how do you protect yourself? And what are the implications for vaccines, masks, hygiene, and social distancing?
If you get COVID-19 in the United States right now, chances are high that it’s the Omicron variant, which now accounts for around 95 percent of the country’s reported cases. With dozens of mutations, Omicron is different from the previously dominant Delta variant in significant ways, which means that, after two years of getting a handle on how to manage risk, you might need to shift at least some of your behaviors.
Among the changes, Omicron is more transmissible and better at evading existing antibodies. “To me, the biggest shift, the most shocking thing, is how incredibly infectious this thing is. I have never seen anything so infectious in my life,” says Carlos del Rio, an epidemiologist and infectious diseases specialist Emory University in Atlanta, Georgia. At the same time, Omicron causes different symptoms and seems to lead to less severe disease.
Still, different strains of SARS-CoV-2 share important similarities, and much of the basic public health advice—get vaccinated, wear a mask—remains the same. Here’s what the latest research says about staying safe in the age of Omicron.
Multiple lines of evidence from various parts of the world suggest that the Omicron variant causes a less severe form of COVID-19. In South Africa, where Omicron was first detected in November 2021, a private health insurance administrator reported in mid-December that adults with Omicron were 29 percent less likely to be hospitalized, compared with adults infected several months earlier. In the U.K., the rate of hospital admission among people who went to the emergency room with Omicron was a third of what it was for Delta, according to a summary of research from the U.K. Health Security Agency released on December 31, 2021.
As of early January, U.S. adults with Omicron were less than half as likely to visit the emergency room, be hospitalized, or be put on a ventilator, according to preliminary work by researchers from Case Western Reserve University School of Medicine. Their study, which has not yet been peer-reviewed, examines data for more than 14,000 patients and accounts for their vaccination status and any pre-existing conditions.
Omicron appears to be less severe than Delta in all age groups, even in adults older than 65 and in children too young to be vaccinated, according to the Case Western study. Still, as with other health issues, age remains a factor, del Rio says. “For any disease, if you're older, you're going to do a lot worse,” he says.
People with underlying conditions or compromised immune systems also remain more vulnerable, as do people who are unvaccinated. Although current vaccines are less effective at preventing symptoms from Omicron than from Delta, the U.K. report found that people who were fully boosted were up to 88 percent less likely to be hospitalized with Omicron compared with unvaccinated people. Hospitals around the country report that unvaccinated patients make up the majority of people now in intensive care units.
Omicron is between two and four times more contagious than Delta, according to a Danish study that has not yet been peer reviewed. It’s also better at evading the antibodies triggered by vaccines, which is why it’s causing more breakthrough infections. As a result, more people are getting sick and showing up at hospitals, where more staff are calling in sick, del Rio says.
Omicron has 36 mutations within its spike protein, which is the part essential for anchoring the virus on human cells and infecting them. Though none are peer reviewed, at least half a dozen studies using small animal models—such as mice and hamsters—and laboratory cell cultures have started to reveal how those mutations alter the way that Omicron enters cells and replicates, says John Moore, a vaccine researcher and virologist at Weill Cornell Medicine in New York.
Unlike previous variants, Omicron appears unable to infect lung cells as efficiently, which in turn makes it less damaging and the symptoms less severe. Viral loads are significantly lower in the lungs of Omicron-infected rodents in some studies. But in the upper respiratory tract, which includes the nose and sinuses, Omicron seems to replicate more than a hundred times faster than Delta.
That mix of changes—the preference for the upper airway, better immune invasion, and high transmissibility—reflects how evolution pushes the virus to ensure its own future by replicating and spreading even when that does not make individuals sicker.
All strains of the SARS-CoV-2 virus can infect cells in the mouth, and Omicron may be particularly abundant there compared with other variants, early evidence suggests. In one study that has not yet been peer reviewed, researchers in South Africa tested 382 people who were not sick enough to be hospitalized but still had COVID-19 symptoms. They found that in those with Delta, nose swabs were more accurate, but for Omicron, saliva tests worked best.
Other studies also suggest that rapid antigen tests that rely on nasal swabs might be especially slow to identify infections with Omicron. In one study posted last week that has not yet been peer reviewed, researchers looked at samples from 30 people who tested positive for COVID-19 around the United States during outbreaks in early December. For most cases of Omicron, PCR tests showed positive days before a rapid test did. Those results echo what people have been reporting on social media, says study coauthor Anne Wyllie, a medical microbiologist at the Yale School of Public Health in New Haven, Connecticut.
Given the growing evidence for Omicron’s prevalence in spit, social media has been full of DIYers and researchers advocating that people swab their throats with at-home test kits. Wyllie has even tried it herself using the swab from a rapid test. The result was negative, but she felt more confident that it was a true negative than if she’d only swabbed her nose.
“It's not what's been authorized by the FDA, and it's a very tricky topic to speak out on because of that,” she says. That’s why many other experts are hesitant to recommend the off-label use. While throat swabs might eventually become part of the testing equation, rapid tests were designed for noses, not throats, says Jill Weatherhead, an infectious disease expert at the Baylor College of Medicine in Houston.
The Centers for Disease Control and Prevention does not currently recommend double masking or the use of specific masks. But other countries, including Austria, France, and Germany, have upgraded their guidelines to recommend medical-grade varieties, such as surgical masks or N95s. And some U.S. experts have spoken out in favor of higher quality masks.
One study found that, if fitted correctly, N95s block an average of 90 percent of exhaled particles, while surgical masks blocked 74 percent. That can make a substantial difference in community spread. In Bangladesh, an intervention boosted the percentage of people wearing surgical masks in some villages from 13 percent to 42 percent. Researchers then found an 11 percent drop in COVID-19 symptoms, with bigger gains in older groups. Evidence on cloth masks is mixed, but wearing a cloth mask over a surgical mask can block more than 85 percent of cough particles, according to some research.
Like prior variants, Omicron is primarily airborne, and experts agree that wiping down surfaces is probably more trouble than it’s worth. “Transmission from surfaces is low,” Wyllie says. Given “the time, energy, money, resources and mental health put into that kind of concern—you’re better spending that on hand-washing, social distancing, and mask-wearing.“
Also, the six-foot rule is more of a reminder that being close to an infected person increases the risk of transmission, says Abraar Karan, an infectious diseases doctor at Stanford University in Palo Alto, California.
It’s too soon to know, and it likely will be months before researchers can tell if Omicron causes symptoms that stick around for the long-term. But some experts are hopeful that long lasting consequences will be less common because of Omicron’s tendency to stay out of the lungs, and because more people are getting vaccinated, which can help prevent infections and lower risk of developing a number of symptoms. “I would suspect we will still see cases,” Wyllie says. “But because we have far more people now vaccinated, I am hoping we see less long COVID-19.”
Editor's Note: This story has been updated to include more detail about John Moore's mask preferences.
Jan 24, 2022 · The SARS-CoV-2 Omicron variant causes less severe disease than Delta although it is better at escaping immune protection by vaccinations and previous infections. The reasons for this have so far ...
Mar 1, 2022 · Omicron has more mutations than other strains: ... This is shorter than with Delta and earlier variants. ... Omicron causes less severe disease than Delta. Part of this may be due to Omicron being ...
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Feb 24, 2022 · In people, Omicron seems to be highly contagious — BA.2 even more so than BA.1 — but to cause less severe disease than other variants. How does it manage that?
