County of Marin - News Releases - COVID-19 Vaccines

For Immediate Release
August 17, 2021

Those with Weakened Immunity OK’d for 3rd Doses

COVID-19 vaccine intended for residents at greater risk of serious illnesses

San Rafael, CA – Marin County Public Health officials announced August 17 that a third dose of COVID-19 vaccination is now available for people who have a severely compromised immune system. Eligible individuals should contact their health care provider for consideration of the additional dose.

The expansion of vaccine eligibility follows the decision by the U.S. Food and Drug Administration to extend emergency use authorization on vaccines to allow an additional dose, as recommended by the Advisory Committee on Immunization Practices and approved by the Centers for Disease Control and Prevention (CDC).  

The CDC estimates that about 2.7% of the population of the United States is immunocompromised, including organ transplant recipients, people undergoing cancer treatment, and those with other immunodeficiencies. In Marin, approximately 10,000 residents meet that criterion. This population is more likely to become infected with COVID-19, even after vaccination, compared with similarly vaccinated but otherwise healthy individuals. They are also more likely to become severely ill due to COVID-19. 

“The rapid spread of the highly contagious Delta variant has added to the vulnerability of our immunocompromised residents,” said Dr. Matt Willis, the County’s Public Health Officer. “A third dose of vaccine adds another layer of protection from infection and serious illness.” 

A third dose is available for moderately or severely immunocompromised people no sooner than 28 days after their second dose of either Pfizer or Moderna vaccine. The FDA authorization does not extend to those who received the Johnson & Johnson vaccine. The additional dose will be matched to the initial vaccination type.

A third dose is not yet authorized by the FDA for use in fully vaccinated people who are not moderately to severely immunocompromised, as defined by the CDC. In a separate communication, the CDC signaled that a wider range of people will be eligible for booster doses possibly starting in September.

“Third doses are only available to small fraction of our residents under the current regulations, based on their immune status,” Willis said. “In a few weeks, depending on the FDA’s decision, we will likely open up to a wider range of people.”

Marin health care providers are in the process of determining which patients are eligible for third doses and inviting them for vaccine appointments when appropriate. Pharmacies across Marin – including CVS, RiteAid, Walgreens, Lucky, Pharmaca, and others – are providing third doses to people who qualify. For those who qualify for a third dose, visit to find a location.


Dr. Matthew Willis
Public Health Officer
Health and Human Services

3240 Kerner Blvd.
San Rafael, CA 94901
(415) 473-4163
Email: Dr. Matthew Willis
Marin HHS website