Is Omicron really gentler?

key takeaways

  • In laboratory studies, the researchers found that Omicron was more susceptible to upper respiratory tract infections.
  • Compared to Delta and other variants, this variant performs worse in the lungs, potentially sparing the organ from severe damage.
  • Real-world data from the U.S. and other countries suggest that the wave of cases fueled by Omicron is proportionally reducing hospital visits compared to other variants.

Real data and anecdotes from infected people suggest that Omicron is milder than previous COVID-19 variants. Several studies published in recent weeks support this view, pointing to how the variant appears to infect the upper respiratory tract but largely leaves the lungs unaffected.

When Omicron emerged, some scientists speculated that the 50 mutations in the variant would allow it to largely evade vaccine immunity and spread rapidly.

Recent anecdotal and epidemiological data suggest that while Omicron is certainly more likely to spread, it still appears to be present around the nose, throat and windpipe. The variant does less damage to the lungs, and the previous variant caused inflammation and scarring that could lead to serious breathing problems.

Why is Omicron more contagious but less severe?

In a preprint study published Wednesday, researchers analyzed data from nearly 53,000 U.S. Omicron patients and 17,000 Delta patients. Patients infected with Omicron were 53% less likely to be hospitalized with symptoms, 74% less likely to be treated in an intensive care unit, and 91% less likely to die from COVID-19. None of these patients required mechanical ventilation.

Early models suggested that Omicron may bind to receptors in human cells more efficiently than previous variants, but preliminary data from animals and human tissues suggest that may not always be the case.

The Syrian hamster is a species that is particularly susceptible to early variants of severe COVID-19​​​. But when infected with Omicron, their lungs had barely detectable viral loads and no signs of inflammation in the bronchioles, according to a preprint study by Belgian researchers.

In another large laboratory study, researchers found lower viral loads in the respiratory tract of Omicron-infected mice and hamsters. The animals also lost weight, suggesting that their disease was less severe.

The study’s lead author, Michael Diamond, MD, a professor of infectious diseases at Washington University in St. Louis, told VigorTip that the findings allow researchers to study which features of Omicron cause it to replicate more poorly in certain cells, and how this relates to disease in humans. results are related.

“It will definitely behave differently,” Diamond told VigorTip in an email. “However, the reason why it behaves differently is unclear. It could be related to the spike, or it could be the effect of other genes.”

In a study using cultured tissue from human bronchi and lungs, researchers at the University of Hong Kong found that Omicron multiplied 70 times faster than Delta in the bronchi within 24 hours of infection. But in infected lung tissue, Omicron replicated at least 10 times slower than the original COVID-19 virus.

If supported by further research, these findings may shed light on how Omicron infection can have less severe disease outcomes. Often, when a COVID-19 infection reaches the lungs, the immune system can overreact, causing inflammation that can lead to breathing difficulties and long-term damage. If the infection primarily resides in the upper respiratory tract, it is less likely to wreak havoc on the rest of the body.

Scientists aren’t sure what makes Omicron more infectious than other variants, but its ability to induce higher viral loads in the mouth and nose may play a role.

“If it’s susceptible to respiratory epithelial cells, then that explains why it’s so susceptible — people spew virus everywhere when they breathe and talk,” said F. Perry Wilson, MD, MSCE, Yale University. The medical school researchers were not involved in the study, he told VigorTip.

Data Shows Omicron Has Fewer Serious Consequences

In some areas hard-hit by Omicron, relatively few people have been hospitalized with COVID-19 in this wave compared to previous surges.

In South Africa, the case rate appears to have peaked and is now declining, the country’s cabinet announced on December 30. Cases peaked at more than 23,000 and have now fallen to less than 7,600 a day.

The death rate typically picks up weeks after a surge in cases, but is still rising in South Africa. Still, in the second week of the wave driven by Omicron, 1.7% of COVID-19 cases resulted in hospitalizations, compared with 19% in June 2021, according to South African Health Minister Joe Phaahla.

However, the data comes with caveats. Around 60-70% of South Africa’s population may have been infected with COVID-19, which means they may have developed a stronger immune response. In addition, South Africa’s population is relatively young, with a median age of just under 28, a full decade younger than the United States.

In the U.S., COVID-19 hospitalizations this week surpassed the record set in January 2021. At the same time, the number of cases is set to triple to a peak last winter of more than 750,000 a week.

On an individual level, however, scientists are still working to understand how Omicron infection behaves differently from other variants. For example, it’s unclear whether Omicron would be less severe in unvaccinated older adults.

Mild COVID still overloads health systems

Wilson said it’s better to use real-world epidemiological findings to measure the severity of Omicron, rather than data “from a test tube.”

“We’ll find out if it’s milder because millions of people are infected in one day,” he added.

Even though Omicron is indeed less severe, its high transmissibility means that more people are infected with the virus, increasing those who are vulnerable to severe disease (such as the unvaccinated, the immunocompromised or the elderly people) risk of exposure to the virus. The surge in cases has overwhelmed the health system.

“For unvaccinated people or uninfected people, I don’t think the severity of the disease is low,” Dr. Kamlendra Singh, a professor of molecular microbiology and immunology at the University of Missouri, told VigorTip. “Do what you can to protect yourself.”

Getting vaccinated and receiving boosters when eligible remains the best way to avoid hospitalization and death from COVID-19.

what does this mean to you

Although Omicron is unlikely to cause serious illness, the results can still be fatal if you are not vaccinated. Health experts insist that being adequately vaccinated and receiving booster shots when eligible is the best way to protect yourself from serious disease.

The information in this article is current as of the date listed, which means that you may have updated information as you read this article. For the latest updates on COVID-19, visit our Coronavirus news page.

Correction – January 12, 2022: This article has been updated to include the latest research on Omicron severity.