Federal officials waited months before making all American adults eligible for a COVID-19 booster shot — meaning millions of Americans may not have the strongest possible protection as they head into holiday travel, Axios' Caitlin Owens writes.

Why it matters: Vaccinated people, even without a booster, still have very strong protection against serious illness or death.

• But a third shot drastically increases people's defenses against even mild infections, which could in turn help reduce the virus' spread.

What they're saying: "We have a consensus. Boosters are very important in maintaining people's defenses against COVID. We need to get as many people vaccinated and boosted [as possible] as the winter sets in," David Kessler, the chief science officer of Biden's COVID response, said in an interview.

Context: Preliminary data released months ago suggested a significant decline in the vaccines' effectiveness at preventing infection, although they held up well against severe disease.

• Based on that data, the Biden administration had hoped to begin allowing booster shots in September for any American adult who was at least eight months removed from their second dose.
• The CDC and the FDA opted instead to only authorize boosters for seniors and people with high-risk medical conditions, before opening them to everyone last week.

In the meantime, red and blue states alike decided to ignore the CDC and open up booster eligibility on their own.

• Millions of people who weren't technically eligible for boosters got them anyway, and a large portion of the most vulnerable patients still haven't gotten one.
• Where it stands: Only 41% of vaccinated Americans 65 and older have received a booster shot, as have 20% of all vaccinated adults, per the CDC.

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Two-in-three Americans will celebrate this Thanksgiving with friends or family outside their immediate households, and about half of those say their gatherings could include unvaccinated people, Axios' Margaret Talev writes in the latest installment of the Axios/Ipsos Coronavirus Index.

Why it matters: Vaccinations and booster shots are giving more people the confidence to resume traditions like sitting around a packed table with masks off. But many are doing so with heightened awareness of what they don't know when it comes to their holiday companions.

• This year, 31% see a large or moderate risk in seeing friends or family for Thanksgiving — way down from 64% a year ago.
• People's assessment of overall risk of returning to their normal pre-COVID lives is also down, with 44% seeing it as a large to moderate risk this year compared with 72% last year.
• But when Americans are asked how concerned they still feel about the virus, the numbers haven't diminished all that much: 69% compared with 85% a year ago.

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Private equity firms Bain Capital and Hellman & Friedman acquired Athenahealth, an electronic health records vendor for physician practices, for $17 billion, Axios' Bob Herman writes.

Why it matters: This is one of the largest leveraged buyouts of the year, and it means the previous private equity firms that took Athenahealth private in 2018 — Veritas Capital and Evergreen Coast Capital, a subsidiary of Elliott Management— tripled their investment.

By the numbers: Athenahealth is now almost as valuable as Cerner, the dominant hospital electronic health records vendor, which has a market cap of $21.6 billion.

The big picture: Private equity firms have flocked into health care over the years, especially in 2021.

• Some of the other major, most recent PE-backed deals involve medical supplier Medline, hospital chains LifePoint and Kindred, outsourcing firm QHR Health and a new mental health provider called Geode Health.

The American Hospital Association, the American Medical Association and the American Nurses Association teamed up to release a new "Forever Grateful" TV and digital ad campaign on Monday to thank health care workers.

Why it matters: The campaign comes in the face of record levels of reported health care worker burnout tied, in part, to the prolonged emergency response to COVID-19.

• The AHA also released a new video thanking health care professionals working in America’s hospitals and health systems for their work.

• Harris announces $1.5B investment in health care workforce. (ABC News)
• More than 90% of federal workers got COVID shot before deadline. (Axios)
• Could one shot kill the flu? (The New Yorker)