In a new study from the University of North Carolina, researchers found that the omicron variant is three times more contagious than delta.
Remember alpha, the first COVID-19 variant? It first appeared in Great Britain in late 2020.
Alpha put the world on alert that mutations can change everything we thought we knew—within mere weeks—about what to expect from COVID-19.
Back then, the team was skeptical of reports that alpha was 50% more infectious than the original coronavirus, SARS-CoV-2.
In the current study, they built a model to estimate the infectiousness of new viral variants and better predict case numbers once a new variant emerges.
They used health data available from Denmark to calculate a value known as the reproductive number (R0) for alpha.
This value characterizes the average transmissibility of an infectious disease in a susceptible population with little to no immunity. (Back when alpha was spreading, vaccines were not yet widely available in Denmark.)
Denmark engages in more testing and genetic sequencing per capita than the United States. This means their health data more accurately reflect a week-to-week snapshot of the viral variants present, and in what proportion.
Using a method called maximum likelihood estimation, the team predicted case numbers of a new variant before the variant has been determined in positive tests.
They showed that the delta variant was about two times more infectious than alpha, and that omicron was about three times more infectious than delta in the Danish population.
By the time omicron began spreading in Denmark, about 82% of its population was fully vaccinated. Because of this, the model is estimating the advantage of omicron in a population with a high level of vaccine immunity.
Because the Danish population has a higher proportion of vaccinated people than the U.S, or even North Carolina, it is difficult to draw a direct comparison for forecasting omicron’s infectiousness here.
In North Carolina, about 35% have not received their first shot. This means there are more susceptible people than in Denmark and the advantage omicron has over delta could be different.
If you care about COVID, please read studies about this drug can block multiple COVID-19 variants and findings of this stuff adds fuel to COVID-19 inflammation.
For more information about COVID, please see recent studies about inexpensive heart drug could help treat severe COVID-19, and results showing that you need three COVID-19 exposures to get a broad immunity for omicron.
The study was conducted by Carolina economist Peter Reinhard Hansen et al.
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