Welcome to open season for COVID-19 booster shots

• The US is entering "open season" for booster shots, a drug industry analyst said Friday.
• The majority of adults who got Pfizer's vaccine are now eligible for a booster.
• There's still no guidance for people who got J&J or Moderna shots.

The booster-shot campaign in the US is here.

Despite more than a month of messy debate around boosters, most adults in the US who got the Pfizer-BioNTech vaccine are eligible to get an extra shot. The statements touting boosters are already flooding in, from President Joe Biden, governors, and pharmacies.

Dr. Rochelle Walensky, the head of the Centers for Disease Control and Prevention, overruled her agency's own advisors to expand eligibility for a Pfizer booster to more adults. The CDC's final recommendations align with the Food and Drug Administration. The following groups are eligible for a booster:

• People age 65 and older
• Residents of nursing homes and assisted living facilities
• Adults 18-64 years old with a qualifying medical condition, such as asthma, diabetes, COPD, high blood pressure, being overweight, being pregnant, sickle-cell disease, being a smoker, and substance abuse disorders.
• Adults 18-64 years old who are "at increased risk for COVID-19 exposure and transmission because of occupational or institutional setting"

If that sounds like a huge chunk of the US population, it's because it is. Biden said on Friday that about 60 million people in the US are eligible for boosters, or will be soon.

To highlight just a couple of criteria, 74% of adults in the US are overweight or obese by the CDC's definition, and therefore would qualify. Or, if you work in-person, that could be enough to put you at "increased risk for COVID-19 exposure" and qualify.

In fact, the key eligibility criteria is probably being six months removed from the second dose. Only about 50 million people in the US were fully immunized six months ago, according to CDC data.

Geoffrey Porges, a drug industry analyst at SVB Leerink, called it "open season for boosters" in a Friday research note.

The analyst said he expects "vaccination centers, clinics, and pharmacies to be swamped with vaccination appointments for 'the worried well' in addition to the truly eligible subjects at increased risk such as the elderly and the immunosuppressed or otherwise at high risk."

About 100 million people in the US have received two shots of the Pfizer vaccine, accounting for about 55% of the nation's immunizations.

The rollout of booster shots is limited, at least for now, to Pfizer vaccine recipients. The FDA and CDC have not provided guidance for people who got Moderna and J&J shots.