Omicron is responsible for an increase in coronavirus infection cases in the U.S. However, its rise to prominence has been more gradual than previously estimated, according to an updated federal modeling.
Omicron accounted for an estimated 58.6% of sequenced U.S. virus cases in the week ending Dec. 25, the Centers for Disease Control and Prevention’s Nowcast model showed Tuesday, up from an estimated 22.5% a week earlier. According to the CDC the once-dominant Delta strain was responsible for 41.1% cases during the most recent period.
Based on genome-sequencing information, Nowcast calculates levels of variant prevalence.
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This week’s figure is a significant revision to a prior estimate that said Omicron was responsible for 73% sequenced infections. The reading showed that Omicron had leapt to the top almost immediately, surpassing 3% in all cases during the previous week.
A spokesperson from the CDC stated that the agency had to adjust the Omicron percentage due to additional information. According to the spokesperson, Omicron is on the rise in frequency.
Learn more Omicron: The Real Concerns for U.S. Doctors
Omicron has been spreading across the U.S.A since it was first detected in California, Dec. 1. The CDC estimates that 88% of the cases in New York City and New Jersey are due to Omicron. However, there are some parts of the country where Delta continues to be dominant. This includes some Midwestern states, New England and New York.
Omicron’s rise has coincided with the holiday season in the U.S., stoking fears of another surge that could overwhelm the already exhausted health-care system. An average of 206,577 cases are recorded every day, according to the CDC, nearing levels not seen since last year’s winter wave.
Incubation period
According to CDC Tuesday, this new variant could have a shorter incubation time and be more likely than others strains to cause reinfections. The agency’s findings were based on an omicron outbreak among a six-person household, which included one person who was fully vaccinated, four previously infected people, and one person who tested positive for the first time.
Researchers found that the average time between infection and symptoms was five days for Omicron variants. However, this strain’s incubation period is only three days. The CDC reported that people with previous infections had similar symptoms to those who have not been infected. This is consistent with earlier research which suggested Omicron can cause less severe illnesses than others.
“The horrific scenes that we saw a year ago—intensive care units being full, lots of people dying prematurely—that is now history in my view, and I think we should be reassured that that’s likely to continue,” said John Bell, regius professor of medicine at the University of Oxford in England. He spoke to BBC Radio 4’s Today program after the U.K. government said it wouldn’t tighten COVID-19 restrictions before the end of the year.
Although the illness is reported to be milder, it still has the potential for putting stress on the economy. Because of shortages of personnel, U.S. airlines cancelled thousands of flights in the vicinity of Christmas.
Monday’s announcement by the CDC reduced the time required to isolate people who are positive and the quarantine period that was given for anyone who has been infected. The CDC advised that both the positive and negative groups continue to use a mask for activity. These new precautions could reduce disruption in schools and workplaces during the surge.
