Delta Variant Infection Doubles Odds of COVID Hospitalization: Study

FRIDAY, Aug. 27, 2021 (HealthDay News) -- The Delta variant is not only much more infectious than earlier versions of the new coronavirus, but it's also twice as likely to land you in the hospital with life-threatening complications, new British research shows.

"Our analysis highlights that in the absence of vaccination, any Delta outbreaks will impose a greater burden on health care than an Alpha epidemic," co-lead study author Anne Presanis, a senior statistician at the University of Cambridge's MRC Biostatistics Unit, said in a statement.

However, the data also shows that the unvaccinated have much more to fear from the Delta variant, noted Dr. Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security in Baltimore.

In this study, about 2% of people who contracted COVID-19 were fully vaccinated, while 74% were unvaccinated and 24% were partially vaccinated.

"The study goes beyond the anecdotal information that had been reported on the Delta variant and does suggest that there could be an increased risk for hospitalization with the Delta as opposed to the Alpha variant," Adalja said. "Importantly, the study shows this is really a phenomenon of the unvaccinated, as vaccination nullifies whatever effect may be happening."

For this study, published Aug. 27 in The Lancet journal, researchers analyzed data from more than 43,300 COVID-19 cases in England March 29-May 23, 2021.

Four out of five people who contracted COVID during the study period had the Alpha variant, although the data showed the Delta variant was quickly spreading across England, researchers said. The Alpha variant was first detected in Britain, while the Delta variant emerged in India.

By the last week of the study, Delta accounted for about two-thirds of new COVID cases and had become the dominant strain in England.

People who contracted the Delta variant were 2.26 times more likely to be admitted to a hospital within two weeks of their first positive COVID test, compared to those sick with Alpha, researchers found. That was after researchers controlled for other factors that put people at high risk for severe COVID.

A person with the Delta variant also had one and a half times greater risk of requiring emergency care or hospital admission within 14 days of infection, compared to patients with the Alpha variant.

The Delta variant appears to have evolved in a way that makes it more dangerous to people than earlier strains were, said Dr. Aaron Glatt, chief of infectious diseases at Mount Sinai South Nassau in Oceanside, N.Y.

"This is some evidence that it is more serious," Glatt said. "It appears to attach better [to human cells] and seems to evade some of the normal defenses."

Adalja said he hopes future studies will also track the type of care that Delta patients require. For example, do they have lower oxygen levels than people with the Alpha variant when they get to the hospital? And are they more likely to require intensive care or mechanical ventilation?

"It's important to unravel this study and pursue questions about what is prompting hospitalization in Delta versus Alpha variant patients," Adalja said.

More than anything, this study again underscores the need for everyone to get vaccinated, Glatt said.

"The vaccine still works fantastic in preventing serious illness, and these results are all the more the reason to get vaccinated," Glatt said. "It'll diminish the likelihood that you get COVID, and even if you get it, you'll still be more protected if you're vaccinated."

More information

The U.S. Centers for Disease Control and Prevention has more about the Delta variant.

SOURCES: Amesh Adalja, MD, senior scholar, Johns Hopkins Center for Health Security, Baltimore; Aaron Glatt, MD, chief, infectious diseases, Mount Sinai South Nassau, Oceanside, N.Y.; The Lancet, study and news release, Aug. 27, 2021