The highly transmissible coronavirus variant first detected in the United Kingdom, B.1.1.7, may already be dominant across the United States, according to a CNN report. A recent study published in the journal Cell investigated the prevalence and dynamics of the variant of concern in the United States. While the variant was first detected in the US at the end of December 2020, the study revealed that several independent introductions in the country occurred in late November 2020, with community transmission spreading it to most states within months.
The researchers estimated that the proportion of cases caused by B.1.1.7 was increasing at a rate of around 7.5% per day and doubling in frequency about every week and a half, suggesting that the variant would become dominant across the US states by March. "I think we are there," William Lee, the co-author of the study, was quoted by CNN as saying. However, he added that “it's hard to say for sure", given gaps and delays in the data.
According to the US Centers for Disease Control and Prevention (CDC), 11,569 cases of Covid-19 caused by B.1.1.7 variant has been reported in the US as of March 30. However, the US health agency said that the cases do not represent the total number of the variant that may be circulating in the country but only such cases that have been found by analysing positive samples.
The CDC has not revealed whether the variant is dominant across the United States but an early study by its own scientists had predicted that this would be the case by March. “The modeled trajectory of this variant in the US exhibits rapid growth in early 2021, becoming the predominant variant in March,” the study published in January said.
{{/usCountry}}The CDC has not revealed whether the variant is dominant across the United States but an early study by its own scientists had predicted that this would be the case by March. “The modeled trajectory of this variant in the US exhibits rapid growth in early 2021, becoming the predominant variant in March,” the study published in January said.
{{/usCountry}}Citing the “most recent data”, CDC Director Dr Rochelle Walensky on Wednesday said at a briefing that B.1.1.7 is “about 26% of circulating virus right now”. Walensky apparently cited the preliminary data of samples collected in the two weeks leading up to March 13, which is in line with the data shared on CDC’s website, and since then, nearly two doubling periods have passed. A CDC spokesperson told CNN that "national prevalence estimates are inherently delayed by a few weeks."