U.S. Covid-19 Update: U.K. Variant Now Dominant Cause Of New Infections

UPDATED with latest: U.S. Covid-19 have risen in the past three weeks, the Centers for Disease Control reported on Wednesday. CDC officials also reveealed that the more infectious variant first discovered in the U.K. — often called B.1.1.7 — has become the chief source of new infections in the country.

CDC Director Dr. Rochelle Walensky said on Tuesday that B.1.1.7 is now dominant not just among the different variants, but over and above what had been called the “wild variant,” which has accounted for the majority of infections to date. “It is the most common lineage, period,” she said. See below for a CDC chart demonstrating the growth of B.1.1.7 over the wild variant in the U.S., known as B.1.2.

Walensky said last week she felt a sense of “impending doom.” That may have been prescient. While key data across the country is undeniably better than at any time during the winter surge, some of the numbers are beginning to swing in the wrong direction.

According to the New York Times, the U.S. is concerned about reports of increasing cases in and around childcare centers and youth sports teams. Hospitals are apparently seeing more people in their 30s and 40s with “severe disease” being admitted. The nature of the U.K. variant may be the cause.

CDC Director Dr. Rochelle Walensky said that the highly contagious variant of the coronavirus first discovered in the UK is now the most common strain of the virus in the U.S. and urged Americans to get vaccinated as soon as possible https://t.co/bgtKzwMyVs pic.twitter.com/XNVTsqRBVJ

— Reuters (@Reuters) April 7, 2021

The CDC says B.1.1.7 is not only 50% more transmissible, but is thought to be less susceptible to monoclonal antibody therapeutics and convalescent and post-vaccination sera, according to the CDC. Those are treatments used to address infections. In addition, B.1.1.7 is likely creating “increased severity based on hospitalizations and case fatality rates.” That may account for the rise in severe cases among younger patients, who are generally less well vaccinated than Americans over 50.

uk-variant-covid-cdc — Chart noting attributes of U.K. variant CDC

Outbreaks in Michigan, Minnesota and Illinois are under scrutiny, and numbers released by Los Angeles health officials this week indicate a rise of B.1.1.7 in the nation’s second-largest metropolis, as well.

The majority of samples genomically analyzed in Los Angeles County last week turned out to be variants of concern. That list was led by the U.K. variant.

While B.1.1.7 has been present in CA for months, its surge in L.A. is surprising because for at least the past four weeks the homegrown “West Coast” variant — B.1427/B.1429 — has predominated in the state by a very wide margin. Numbers in the chart below demonstrate that, with the total instances of West Coast variants identified in the county to date sitting at 415 and the number of U.K. variants identified to date at 169. That’s 42% of all tests coming back with as B.1427/B.1429 and 17% B.1.1.7.

The spread at the state level is even more pronounced. As of April 1, 851 cases of the U.K. variant had been reported in CA. That same report shows, however, that a total of close to 10,000 cases of the West Coast variants had been identified to date.

But last week in L.A., B.1.1.7 spiked to 64% of the variants detected. B.1427/B.1429 was at just 20%.

The “why” may lie in the CDC finding that, while the U.K. variant is 50% more transmissible, the West Coast variant is only 20% more so. The U.K. variant, then, may be outcompeting the less-infectious West Coast strain.

PREVIOUSLY on March 1: The United States crossed the 30 million Covid-19 case threshold on Wednesday, according to Reuters and the New York Times. The milestone comes spring break parties happen across the country and, according to Reuters, “cases are trending higher in 30 out of 50 states.”

Among those states, New York recorded the most significant spike in cases on Wednesday, according to data from the Washington Post. The Empire State had a 7-day rolling average of over 7,300 daily cases. Florida was next with over 4,600, followed by New Jersey with about 4,150 and Michigan with an average of about 3,750 daily cases.

Indeed, CDC Diretor Dr. Rochelle Walensky said on a White House Covid Response Team Zoom conference that “cases continue to increase slightly” across the U.S. On Wednesday, that number was about 55,000. This week’s 7-day rolling average vs. last week’s is up about 3%.

The U.S. on Wednesday had recorded about 545,000 deaths related to the virus.

WATCH NOW: Dr. Fauci and Dr. Walensky are joined by Andy Slavitt to share updates on the latest science, the state of the pandemic, and progress we’ve made in our vaccination program. https://t.co/ePVsNJBF6B

— White House COVID-19 Response Team (@WHCOVIDResponse) March 24, 2021