Three New Studies Suggest Omicron Triggers Milder Illness Than Delta

THURSDAY, Dec. 23, 2021 (HealthDay News) -- In some heartening news for the holidays, three new studies that combed through early data on the new Omicron variant suggest it does not cause severe disease as often as the Delta variant does.

On the other hand, Omicron is so contagious that it will likely increase hospitalizations, and the unvaccinated still need to worry, public health experts said.

“If you are unvaccinated and you have never been infected, it is a little less severe than Delta,” William Hanage, an epidemiologist from Harvard's T.H. Chan School of Public Health in Boston, told The New York Times. “But that’s a bit like saying you’re being hit over the head with one hammer instead of two hammers. And the hammers are more likely to hit you now.”

To slow Omicron's spread, Americans should take rapid COVID-19 tests before holiday events, Christina Ramirez, a biostatistician at the University of California, Los Angeles, told the newspaper.

They also should gather outside, stay near open windows or find other ways to improve ventilation, Ramirez said.

“I don’t want to be alarmist, but I don’t think that you can let your guard down,” she added.

The three new studies suggesting Omicron infections are milder were conducted by researchers in South Africa, Scotland and England. At the same time, encouraging news that the wave of Omicron infections seems to have already peaked arrived from South Africa on Wednesday.

The new South African study found that the risk of hospitalization was about 70% lower in Omicron cases compared to people infected with other COVID variants. Those researchers cautioned that their data was gathered during the early stage of the Omicron wave, when it may have been more likely that people with mild symptoms were admitted to the hospital because the infection rate was low.

They also suggested that because Omicron was more likely to reinfect people who had already had the virus, it might be causing a higher number of milder cases. While it can get past the antibodies created during earlier surges, it may not have been able to evade slower immune responses that prevent more serious disease, the Times reported. About 70% of those in the study had experienced previous COVID-19 infections and 30% had been vaccinated.

Two separate British studies buttressed the South African findings, where researchers again found reduced hospitalizations with Omicron cases.

During November and December, Omicron infections in Scotland were associated with a two-thirds reduction in the risk of hospitalization compared with the Delta variant.

Meanwhile, researchers in England found Omicron patients were 15% to 20% less likely to end up in hospitals compared to Delta patients, and they were 40% to 45% less likely to be hospitalized overnight or for a longer period.

The Imperial College of London researchers theorized that previously acquired immunity was contributing to Omicron’s milder infections.

Still, the variant could still put a lot of people into hospitals very quickly, Mark Woolhouse, a professor of infectious diseases at the University of Edinburgh, told the Times.

“We’re not at a place to treat this as a cold,” Azra Ghani, a co-author of the Imperial College London study, told the Times.

The results are preliminary, the researchers noted, and the statistics may shift as cases spread to older people at higher risk of hospitalization.

Meanwhile, Omicron has spread to all 50 U.S. states as the holidays arrive. A bright note: The U.S. Food and Drug Administration on Wednesday authorized the first pill to treat COVID-19.

Paxlovid, developed by Pfizer, is authorized for COVID-19 patients ages 12 and up who are at risk of becoming severely ill. The pills are likely to work against Omicron, Pfizer has said.

While more than 204 million Americans are fully vaccinated, only 63.2 million have received their boosters so far, according to the CDC. The boosters offer the strongest protection against Omicron infection, health officials have said.

While some countries have vaccinated 80% of their populations, only 62% of Americans have been vaccinated.

For now, experts said, everyone will have to endure some uncertainty about what this variant will do in the weeks ahead.

“We need to be willing to wait for answers and be willing to swim in the uncertainty a little bit,” Nicholas Reich, a biostatistician and infectious disease modeler at the University of Massachusetts Amherst, told the Times.

More information

Visit the U.S. Centers for Disease Control and Prevention for more on the Omicron variant.