SACRAMENTO — After the initial release of the COVID-19 vaccines in November 2020, the ongoing real-time research of the effectiveness of the vaccinations continue. 

Last week the Western States Scientific Safety Review Workgroup completed its review of the federal process and has recommended a booster dose for recipients of the Moderna and Johnson & Johnson COVID-19 vaccines. 

Recipients of the Moderna vaccine may receive a booster shot six months after completing their primary vaccination series, and recipients of the Johnson & Johnson vaccine may receive a booster shot two months after receiving their first dose.


The Workgroup also approved the “mix-and-match” strategy, endorsed by the Federal Drug Administration (FDA) and the Center for Disease Control (CDC). This allows anyone qualifying for a booster to receive any of the FDA-approved vaccines. 

Individuals may receive either the same or a different COVID-19 vaccine, depending on advice from a health care provider, individual preference, availability or convenience. 

The Workgroup, made up of nationally-acclaimed scientists with expertise in immunization and public health, has concurrently and independently reviewed the FDA’s actions related to COVID-19 vaccines. It will continue to evaluate other COVID-19 vaccines as they go through the federal process.

The Workgroup provided its confirmation to the Governors of California, Nevada, Oregon, and Washington.

“California is leading the nation in vaccinations, with 52 million administered and 86 percent of the eligible population having received at least one dose—today’s Western States Scientific Safety Review Workgroup recommendation on booster shots will help keep the momentum going as we enter the winter months. Through our investments in targeted outreach and robust community-based partnerships, our work continues to reach the hardest-hit communities. Vaccines are how we end this —I encourage all eligible Californians to visit to schedule an appointment for their first dose or find a booster shot to keep themselves and their community healthy,” said Governor Gavin Newsom. 

San Luis Obispo County 

The County of San Luis Obispo Public Health Department announced on Tuesday, Oct. 26, that they will begin to offer booster doses of the Johnson & Johnson (J&J) and Moderna vaccines by appointment to eligible community members at Public Health Clinics in Grover Beach, Paso Robles, and San Luis Obispo. 

Booster doses are also available from local pharmacies and healthcare providers. 

Booster doses for Johnson & Johnson along with Moderna vaccines have been formally approved by the U.S. Food & Drug Administration (FDA), Centers for Disease Control & Prevention (CDC), and Western States Scientific Safety Review Workgroup. 

“The most important dose of vaccine is still the first one, and I encourage everyone who has not yet started or completed their vaccine series to make an appointment today, ” said Dr. Penny Borenstein, County Health Officer. “We’re also happy to now offer this additional boost of protection, which is especially important for those most at risk of severe outcomes of COVID-19.” 

All those who received the J&J vaccine (age 18+) are eligible to get a booster dose two months or more after receiving the initial vaccination. 

Those who received the Moderna or Pfizer vaccines are eligible for a booster dose at six months or more after their initial series if they are: 

  • • 65 years and older 
  • • Age 18+ who live in long-term care settings 
  • • Age 18+ who have underlying medical conditions 
  • • Age 18+ who work or live in high-risk settings 
  • • Age 18+ who are at an increased risk of social inequities 

With this update, the FDA, CDC and Western States workgroup have also authorized “mix-and-match” (heterologous) booster shots, meaning those eligible for a booster dose may receive any type of vaccine. Public Health clinics will continue to schedule appointments by vaccine type, and residents may select their type of vaccine when scheduling an appointment. Walk-ins will be available as supply allows but may not offer a choice of vaccine type. 

“It’s held true throughout this pandemic that the best vaccine is the one available to you and which you feel comfortable getting—and that is true with boosters, too, ” said Dr. Penny Borenstein, County Health Officer. “For those seeking guidance on vaccine type based on your personal health situation, I encourage you to talk with your doctor. Since most hospitalized persons who were fully vaccinated are over 65 years old, this group should prioritize getting a booster dose as soon as possible.” 

According to the County, more than 72.3 percent of eligible San Luis Obispo County residents have received at least one dose of vaccine, and 65.5 percent are fully vaccinated. 

For updates on COVID-19 in SLO County, visit or call the recorded Public Health Information Line at (805) 788-2903. Phone assistance is available at (805) 781-5500 Monday through Friday, from 8 a.m. to 5 p.m. For more information on COVID-19 vaccine, visit