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Combination images of Democratic Sens. Elizabeth Warren and Cory Booker. Photo: Anna Moneymaker/Getty Images; Drew Angerer/Getty Images

Sens. Elizabeth Warren (D-Mass.) and Cory Booker (D-N.J.) announced separately Sunday that they've tested positive for breakthrough cases of COVID-19.

Why it matters: Both Warren and Booker in Twitter posts reported mild symptoms and spoke of their gratitude of being fully vaccinated against the virus and having booster shots and advocated for others to do the same, as U.S. health officials warn of a surge in cases due to the Omicron variant.

A tweet previously embedded here has been deleted or was tweeted from an account that has been suspended or deleted.

Details: Hours after Warren confirmed she'd contracted the virus, Booker tweeted that he had "tested positive for COVID-19 after first feeling symptoms on Saturday."

  • "My symptoms are relatively mild," he added. "I'm beyond grateful to have received two doses of vaccine and, more recently, a booster — I'm certain that without them I would be doing much worse."

The big picture: Omicron variant has fueled fears of a winter coronavirus surge due to the variant's high transmissibility and its ability to evade immune protection.

By the numbers: Detected in 89 countries, Omicron has caused daily caseloads to double every 1.5 to 3 days in areas where there is community spread, according to the World Health Organization.

Editor's note: This article has been updated with details of Booker's positive test result.

Go deeper

Jan 15, 2022 - Health

Experts warn of more COVID-19 variants after Omicron

Three COVID-19 testing companies place testing locations outside Grand Central Terminal on Jan. 14 in New York City. Photo: Alexi Rosenfeld/Getty Images

Experts are warning that subsequent COVID-19 variants are likely to come after Omicron, AP reports.

Why it matters: The warnings come as there's no guarantee that subsequent variants "will cause milder illness or that existing vaccines will work against them," underscoring the need for widespread vaccination, AP writes.

Updated 4 mins ago - Politics & Policy

Omicron dashboard

Illustration: Brendan Lynch/Axios

  1. Health: Pfizer and Moderna boosters overwhelmingly prevent Omicron hospitalizations, CDC finds — Omicron pushes COVID deaths toward 2,000 per day — The pandemic-proof health care giant.
  2. Vaccines: The case for Operation Warp Speed 2.0 — Starbucks drops worker vaccine or test requirement after SCOTUS ruling — Kids' COVID vaccination rates are particularly low in rural America.
  3. Politics: Biden concedes U.S. should have done more testing — Arizona says it "will not be intimidated" by Biden on anti-mask school policies.
  4. World: American Airlines flight to London forced to turn around over mask dispute — WHO: COVID health emergency could end this year — Greece imposes vaccine mandate for people 60 and older — Austria approves COVID vaccine mandate for adults.
  5. Variant tracker
Updated 1 hour ago - Economy & Business

Janet Yellen co-opts Reaganomics phrase for new Davos speech

Treasury Secretary Janet Yellen at a speech this week. Photo: Alex Wong/Getty Images

The U.S. needs to focus on increasing its productive potential, Treasury Secretary Janet Yellen told world leaders Friday, calling for what she terms "modern supply side economics."

Why it matters: She co-opted a phrase traditionally used by political conservatives to describe low-tax and deregulatory policies — and framed the Biden administration's initiatives as the best path forward to achieve greater national prosperity.