Essex County's vaccination centers will provide booster coronavirus vaccine shots to people with compromised immune systems.

The county announced the availability less than a day after the Food and Drug Administration authorized third doses of the Pfizer or Moderna vaccines for people who have had organ transplants or who otherwise have weakened immune systems.

Janet Woodcock, the FDA's acting commissioner, stressed Thursday other people who are fully vaccinated and otherwise protected don't need an additional dose of vaccine at this time.

"FDA is actively engaged in a science-based, rigorous process with our federal partners to consider whether an additional dose may be needed in the future," she said in a tweet.

The FDA's announcement didn't address booster shots for individuals who'd received the one-dose Johnson & Johnson vaccine.

Essex County will begin administering third doses of Moderna or Pfizer vaccines beginning Saturday, Aug. 14 at its centers at the former Kmart building in West Orange and Essex County College in Newark.

Both sites allow walk-ins for coronavirus vaccinations in general, but will require appointments for booster shots. Appointments can be made at or 973-877-8456. Those seeking booster shots will not need notices from their doctors or other documentation of their weakened immune systems.

County Executive Joseph N. DiVincenzo Jr. said in an announcement Essex was "committed to making getting a booster shot as easy and efficient as possible."

Hours of operation will be expanded at the centers to six days a week — only off on Sunday. The centers will be open from 9 a.m. to 5 p.m.

Booster shots will not be available at the county's mobile clinics or pop-up sites, including the vaccination event planned for Aug. 29 at the Wally Choice Center in Glenfield Park, hosted alongside the 14th annual Back 2 School supply giveaway hosted by the Montclair Sentinels 16-87.