New Study Finds Omicron Variant Is As Dangerous as Previous Strains
A large study of the omicron variant of COVID-19 has found that it is just as severe as other variants that came before, contradicting earlier research from South Africa and elsewhere that claimed omicron was more transmissible but less severe.
The new study looked at the outcome of more than 130,000 COVID-19 patients across 13 hospitals in the U.S. state of Massachusetts.
The study’s authors report that hospitalizations and deaths appeared higher with previous variants. However, by adjusting omicron numbers for factors such as demographics, comorbidities and immunity levels, omicron’s rate of hospitalization and death were virtually the same.
“Our analysis suggests that the intrinsic severity of the Omicron variant may be as severe
as previous variants,” wrote the researchers, led by Dr. Zachary H. Strasser of Massachusetts General Hospital in Boston.
The study contradicts research done in South Africa and elsewhere soon after the variant turned up in samples from Botswana and South Africa. That research suggested that omicron was less deadly than earlier variants even though it was more transmissible and could overcome existing immunity.
Since that original strain of omicron was discovered, omicron has produced multiple variations of itself known as sublineages, with mutations that continue to help it get past existing immunity.
The study focused on the BA.2 sublineage, which is driving infections in 16 African countries as well as Europe and North America. The original omicron variant is present in 48 African countries.
Two other omicron sublineages – B.A.4 and B.A.5 — caused a rapid fifth wave of infections in South Africa. Tulio de Oliveira, director of South Africa’s Centre for Epidemic Response and Innovation (CERI), reported on Twitter on May 17 that the fifth wave already had peaked with fewer hospitalizations and deaths than expected.
About 90% of South Africans have been exposed to COVID-19 during the pandemic, granting them some form of protection from the most severe effects of infection.
“It looks like we have enjoyed that period of downward trend and now we are beginning to see how countries report ticking up for the virus,” Dr. John Nkengasong, outgoing head of the Africa Centres for Disease Control and Prevention, said during a recent press briefing.
As of early May, the continent saw a 25% increase in new COVID-19 cases compared to the preceding four weeks. Many of the new cases occurred in South Africa, which saw a 57% jump. Deaths were up 7% to 252,000 continentwide.
Researchers believe when it came to predicting the behavior of omicron, early studies were too small or omitted patients that could have been included.
Determining the exact impact of omicron was complicated by immunity levels, therapeutics, public health measures such as masks, and changing population demographics — elements Strasser’s group call “confounders.” Many of those elements have grown in use since other variants, such as delta, appeared.
“Our findings suggest that, after accounting for confounders, the Omicron variant was as deadly as the previous SARS-CoV-2 waves,” the authors wrote.
Immunity levels hid the strength of omicron by lowering the number of people with severe symptoms. People who contracted omicron also were, on average, younger than those who contracted earlier variants, according to the study.
It’s impossible to compare omicron accurately to previous variants without taking into account those elements, Strasser wrote. Doing otherwise creates a false impression about the risk omicron poses, the authors said.
“It could also lead to mistrust among the public and poor choices by health policy experts,” they wrote.
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