All adult Oregonians who received Pfizer and Moderna COVID-19 vaccines at least six months ago will be eligible to receive a booster shot starting this weekend.

The Western States Scientific Safety Review Workgroup, Oregon’s immunization advisory board, is expected to approve expanded eligibility for booster shots at a Friday evening meeting. The regional board’s impending decision follows the US Food and Drug Administration (FDA) and Centers for Disease Control and Prevention’s (CDC) approvals of broader booster eligibility Friday. The Western States workgroup has previously agreed with all of the FDA and CDC’s COVID vaccine recommendations.

The CDC’s new recommendations say everyone 50 and older “should” get a booster shot and everyone 18 and older “may” get a booster shot if they want to. Booster shots increase the recipient’s immunity to the virus after their initial immunity from the vaccine has waned over time.

Previously, Pfizer and Moderna booster shots were only available to people who are immunocompromised, 65 and older, or at a higher risk of contracting COVID due to their job. With the new eligibility rules, anyone 18 and older who received their second Pfizer or Moderna dose at least six months ago can get a booster shot. According to the Oregon Health Authority (OHA), the new rules will make an additional 1.25 million Oregonians eligible for the additional dose.

“Vaccine supply is unlikely to get in the way of vaccinating people who want a booster,” said OHA spokesperson Rudy Owens. “However, we continue to be concerned about the significant strain on health care and pharmacies across the state to deliver vaccinations in the face of workforce shortages, deferred care for chronic conditions, and need for COVID-19 testing services.”

That strain on healthcare systems may cause some delays in scheduling booster shot appointments. Oregonians can visit the OHA’s vaccine locator website to find their nearest vaccine clinic or pharmacy.

Federal and regional health agencies approved booster shots for Johnson & Johnson vaccine recipients ages 18 and older at the end of October. Johnson & Johnson recipients can get their booster shot two months after receiving their single dose.

As of November 18, 73 percent of people in Multnomah County and 67 percent of all Oregonians have received at least one shot of a COVID vaccine.