Omicron Infections Appear Milder, Three Research Teams Report

Three separate teams of scientists on two continents offer hope that Omicron infections cause mild illness more often than previous variants of the coronavirus, and that the current surge may not be as catastrophic as feared despite rapidly increasing caseloads.

Researchers studied Omicron’s route through populations in South Africa, Scotland and England. Results in each setting suggested that the variant is less likely to send people to hospitals, although it is still preliminary.

“Given that this is ubiquitous and will be very contagious, anything that reduces violence will be for the better,” said Natalie Dean, a biostatistician at Emory University in Atlanta.

Since the Omicron variant was discovered in South Africa in November, scientists have been struggling to find out if it causes more serious illness compared to other variants, and if so, who does.

The new research suggests the variant may have biological properties that make it slightly less dangerous than Delta, the variant that has dominated the world since summer.

But Omicron’s ability to lower the risk of hospitalization in all three countries also appears to be largely due to immunity in these populations. Most of those infected already had protection against serious illness due to previous infections or vaccinations.

While the new research is encouraging, experts warn that the surge in many countries could fill hospitals with Omicron cases, as the variant spreads much more easily than previous versions of the coronavirus.

“I don’t want to raise the alarm, but I don’t think you can let your guard down,” said Christina Ramirez, a biostatistician at the University of California, Los Angeles.

Dr. Americans should do quick tests before holiday events and gather outside, open windows or find other ways to improve ventilation, Ramirez said.

While Omicron may cause milder disease on average, it is also spreading faster than any variant so far. It is currently the dominant variant in the United States, Europe and many other parts of the world.

Still, encouraging news came from South Africa on Wednesday, suggesting these fluctuations may not last as long as before. Omicron fuels record number of new daily cases, but officials reported The wave of infections may have peaked on Wednesday.

As infections in the United States soared to an average of 154,000 daily cases last week, federal health officials added a defense against the growing threat to hospitals. Food and Drug Administration official The first pill to cure Covid-19 on Wednesday offers a highly effective treatment for serious illness.

Developed by Pfizer and known as Paxlovid, the drug is authorized for Covid patients aged 12 and over who are at risk of becoming seriously ill. Pfizer says its pills are likely Omicron variant.

Three studies from the United Kingdom and South Africa confirm that Americans will gain some protection against serious illness from vaccines and booster vaccines. more than that 200 million Americans – more than 60 percent of the population – are now fully vaccinated.

But the USA is behind other countries, some vaccinated more than 80 percent of their population. And only 63 million Americans have received boosters from Omicron, which provide the strongest protection against both serious illness and infection.

South African research Focused on rise in Omicron cases since November. The researchers found that the risk of hospitalization for people infected with Omicron was about 70 percent lower compared to those infected with other variants of the coronavirus.

The authors speculate that the milder cases may be due in part to Omicron’s better success at reinfecting people who already have Covid-19. The variant, while its antibodies may escape previous infections and settle in the body, may not be able to evade the strong but slower immune responses that prevent serious illness.

In South Africa, researchers estimate that around 70 percent of people had Covid infections before the Omicron wave. About 30 percent are vaccinated. The authors were unable to separate the protection afforded by infections from the protection provided by vaccines.

They also warned that their data was collected at an early stage of the Omicron wave, when the overall infection rate was quite low. Infected people with relatively mild symptoms may have been more likely to be admitted to hospitals at the time, before the wards were full.

In ScotlandResearchers studied Delta and Omicron cases in November and December, and looked at how many patients of each variant were admitted to a hospital. The researchers found that Omicron infections were associated with a two-thirds reduction in the risk of hospitalization compared to the Delta variant.

Mark Woolhouse, professor of infectious diseases at the University of Edinburgh and co-author of the new study, said the dramatic increase in Omicron means that even if these preliminary results hold, the variant will still put many people into it. hospitals so fast

Also Wednesday, a research team from Imperial College London compared Omicron and Delta cases in the first two weeks of December and reported a decrease, albeit smaller, reduction in hospital visits than their Scottish counterparts found.

First guesses They suggest that, compared with cases of the delta variant, individuals infected with Omicron are on average 15 to 20 percent less likely to come to hospitals overall and 40 to 45 percent less likely to stay in the hospital overnight or longer.

The team was able to distinguish the consequences of Omicron infection in people who were vaccinated, previously infected, or who did not have any immunity. They confirmed the South African researchers’ suggestion that acquired immunity helps make Omicron infections milder on average.

The difference between the results of the English and Scottish studies may also be due, in part, to differences in the measurements. The Imperial College London team included people who had just visited a hospital, in addition to those who needed to be hospitalized for a more serious illness. Scottish researchers only looked at hospital admissions.

Both teams of scientists warned that their results are still in their infancy. First of all, Omicron is still making its way in Britain and has yet to make much headway among older people who may be at higher risk of hospitalisation.

And even if individual cases are mild, Omicron still poses a serious risk to hospitals as cases explode so quickly. “We’re not in a place to treat it as a common cold,” said Azra Ghani of Imperial College.

William Hanage, an epidemiologist at the Harvard TH Chan School of Public Health, said the new findings make it clear that people who have not been vaccinated and have not yet contracted Covid are at particularly high risk.

He said that since Omicron is spreading rapidly, they are likely to become infected in the coming months. If so, they will not have any immunity to blunt the severity of the infection.

Dr. “If you’re unvaccinated and have never been infected, it’s a little less severe than Delta,” Hanage said. “But that’s a bit like saying you got hit in the head with one hammer instead of two. And the hammers are more likely to hit you now.”

While the past few weeks have brought in a slew of new data on Omicron, there are still many questions about how the coming weeks will unfold and how high hospitalization rates will rise.

Chris Robertson, an epidemiologist at the University of Strathclyde and co-author of the Scottish study, warned that the holiday season will slow the collection of data he and others will need to update their findings.

“Normally, I would be doing this analysis every week, but now it will be two to three weeks before another update comes along,” he said.

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

But a modeling team running a project, Covid-19 Scenario Modeling Center He issued a statement Wednesday making it clear that the writing is already on the wall, despite fine-tuning his estimates.

“The best information we have at this time shows that the threat posed by Omicron is significant and imminent, and individuals and governments need to be prepared to respond accordingly,” they warned.