Delta Variant Seen in a Fifth of U.S. Covid Cases, CDC Says

A healthcare worker wearing protective gloves places a vial containing a Covid-19 test swab into a box at a United Airlines Covid-19 testing site inside San Francisco International Airport. (Photographer: David Paul Morris/Bloomberg)

Delta Variant Seen in a Fifth of U.S. Covid Cases, CDC Says


The delta variant is spreading rapidly in the U.S. and now accounts for a fifth of recent coronavirus cases, the head of the Centers for Disease Control and Prevention said.

Rochelle Walensky said in an appearance at the Milken Institute Future of Health Summit on Wednesday that the rapid growth in the delta variant, which first emerged in India, was seen after the strain accounted for just 3% of cases analyzed several weeks ago.

The delta variant is predicted to be the second most prevalent lineage nationally for the two weeks ending June 19, and it’s already become the predominant lineage in some regions, according to the CDC.

The numbers given by Walensky align with other recent data suggesting the delta variant is gaining a foothold in the U.S.

Genomics-testing firm Helix analyzed about 20,000 samples from Covid-19 tests across more than 700 U.S. counties. It found that the delta variant cases appear to be growing far faster in counties with lower vaccination rates than in areas that have higher levels.

Not only is the strain more transmissible, but there is also some concern that it may lead to more severe illness, Walensky said.

Data are showing the mRNA vaccines made by Pfizer Inc. and Moderna Inc. should work well against the variant, and the CDC is examining how the Johnson & Johnson vaccine performs, she said.

Given the J&J vaccine is similar to the AstraZeneca vaccine, which looks to protect against severe and deadly disease from the variant, the agency anticipates the J&J vaccine will also work well at preventing severe disease, she said.

Despite the rise of the delta variant, virus cases broadly are at their lowest levels since March 2020, Walensky said.

©2021 Bloomberg L.P.

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