A patient takes his own blood oxygen reading with an oximeter at an outpatient clinic. Though Omicron causes less serious COVID-19 symptoms, the variant's high transmissibility has led to more deaths in some areas, researchers say. File photo by Thomas Maresca/UPI | License Photo
May 20 (UPI) -- Massachusetts saw more "excess" deaths during the wave of the COVID-19 pandemic fueled by the supposedly milder, but more contagious, Omicron variant than during the Delta wave, a study published Friday found.
This is despite data indicating that the Delta variant of the virus that causes COVID-19, which was the predominant one in circulation in the United States last summer and fall, produces more serious symptoms in those infected, the researchers said in an article published Friday by JAMA.
The state saw more excess deaths -- or a higher number of fatalities than would be expected over a given period -- during the eight-week Omicron wave, from Dec. 27 through Feb. 20, than in the 23-week Delta wave during the summer and fall.
There were just under 2,300 excess deaths during the Omicron wave compared with about 2,000 during the Delta wave, the data showed.
"In terms of excess death, we found that Omicron was actually much worse for Massachusetts than Delta," Dr. Jeremy S. Faust, one of the study co-authors, said in a press release.
"This could mean that highly contagious variants, even if they cause relatively milder illness, can still lead to substantial excess mortality, even in a highly vaccinated population," said Faust, an emergency medicine specialist at Brigham & Womens Hospital in Boston.
Excess deaths are used to measure the effects of a disease outbreak or other public health emergency, according to the Centers for Disease Control and Prevention.
The agency defines the measure as the difference between the observed numbers of deaths in specific time periods and expected numbers of deaths in the same time periods.
Recent studies using excess deaths have suggested the toll from the COVID-19 pandemic may be much higher than estimated, with perhaps as many as 18 million people killed by the virus globally.
Though the Omicron variant is believed to cause less severe COVID-19 symptoms than earlier strains, it is more contagious, meaning more people will get infected and larger numbers could potentially develop serious illness and die as a result, researchers have said.
Data also indicates that the currently available vaccines from Moderna and Pfizer-BioNTech are less effective against the Omicron variant, though still prevent serious illness in most cases.
For this study, Faust and his colleagues compared excess deaths in Massachusetts during the Delta wave of the pandemic, June 28 through Dec. 5 of last year, to those during the Omicron wave.
They used death certificates filed during each period and compared the totals with the same weeks in prior years, they said.
"Others have reported that the Omicron variant may cause milder COVID-19," Faust said.
"Assuming that's the case, what we're seeing here may reflect just how much more infectious Omicron has been," he said.