LOS ANGELES-With a new wave of COVID-19 infections triggered by Delta variants hitting countries around the world, disease experts are scrambling to understand whether the latest version of the coronavirus has made people—mainly unvaccinated—come I was more ill before.

According to an internal report released on Friday, the US Centers for Disease Control and Prevention warned that Delta Air Lines, which was originally discovered in India and now dominates the world, “may be more serious than an earlier version of the virus.”

The agency cited research in Canada, Singapore, and Scotland that showed that people infected with the Delta variant are more likely to be hospitalized than patients in the early stages of the pandemic.

In an interview with Reuters, disease experts said that these three papers showed that the risk of the mutation is greater, but the research population is limited, and the research results have not yet been reviewed by external experts. Doctors treating patients infected with Delta described the onset of COVID-19 symptoms more quickly, and that there has been an overall increase in severe cases in many regions.

But experts say that more work is needed to compare the results of a large number of individuals in epidemiological studies to determine whether one variant causes more serious disease than another.

“It is difficult to determine the severity and increase of demographic bias,” said Lawrence Young, a virologist at Warwick Medical School in the United Kingdom.

Experts say that in addition, the abnormal speed of Delta’s spread may also cause more severe cases to reach the hospital.

According to the CDC report, Delta is as contagious as chickenpox and more contagious than the common cold or flu.

Shane Crotty, a virologist at the La Jolla Institute of Immunology in San Diego, said that the clearest sign that the mutation may cause more serious disease comes from a study in Scotland, which found that Delta’s hospitalization risk increased by approximately one percent compared to earlier versions. Times.

In the United States, most people who have been hospitalized and died due to the coronavirus have not been vaccinated. But there is evidence that these vaccines are less effective for people with compromised immune systems, including the elderly.

Dr. Gregory Poland, an infectious disease expert at the Mayo Clinic, said that for healthy people who have been vaccinated, if they are infected with COVID-19, they are likely to have only asymptomatic or mild disease.

“But they can pass it on to their families and other people who may not be so lucky,” Poland said. “We have to be vaccinated and wear masks, otherwise we will endure another surge for the fourth time, and with it a worse variant.”

‘Full flame’

Severe illness rates, especially in areas with low vaccination rates, once again make medical staff on the frontline of the pandemic nervous.

“It’s like a wildfire, it’s not a smoldering campfire. It’s burning now,” said Dr. Michelle Barron, senior medical director of infection prevention and control at UCHealth, Colorado.

Barron said that research from China shows that the Delta variant replicates faster than the original strain and produces 1,000 times more virus in the body, which highlights the greatest danger of this new wave.

“It’s hard to tell if they are getting sicker because of the Delta variant, or whether they will get sicker anyway,” she said.

Other doctors say that patients infected with Delta appear to get sicker faster than patients they were treated in the early stages of the pandemic, and in some cases have more severe symptoms.

“We will see more patients needing oxygen soon,” said Dr. Benjamin Barlow, chief medical officer of American Home Care, a chain of emergency care clinics in 28 states.

Barlow said at his clinic in Birmingham, Alabama that about 20% of patients tested positive for COVID-19, up from 2% to 3% a few weeks ago. At that time, it will be assessed whether the patient may be admitted to the hospital and receive oxygen support.

David Montefiore, director of the AIDS Vaccine Research and Development Laboratory at Duke University Medical Center, said the Delta variant is more contagious and causes the disease to attack faster—especially for people who have not been vaccinated.

“Frankly speaking, the severity of this mutation is slightly more serious,” Montefiore said in a live webcast last week. “Not only is it easier to spread, it also makes you sicker.”

(Reporting by Deena Beasley in Los Angeles, Josephine Mason in London and Julie Steenhuysen in Chicago; Editing by Michele Gershberg and Daniel Wallis)