MARIN COUNTY (CBS SF) – Health officials in Marin County urged seniors to receive COVID-19 vaccine booster shots, saying few have received a third dose since the shots became available.

“Vaccines are by far our best line of defense, and to maintain that high level of protection some of us benefit from a booster. It’s that simple,” Dr. Matt Willis, the county’s health officer, said in a statement.

READ MORE: South Bay Retailer Shutters Store in Response to Smash-and-Grab Crime Wave

Health officials said hospitalizations were also rising among vaccinated residents 65 and older.

Willis also cited the recent death of Gen. Colin Powell, who died due to complications from COVID-19. Powell was fully vaccinated, but had other health ailments including multiple myeloma, a type of blood cancer that affects white blood cells and can severely compromise the immune system.

“An additional booster shot can help keep you healthy,” the health officer said.

Doctors also joined the call for seniors to get their booster shots.

READ MORE: Grieving Family Members Call for Justice for Slain Security Guard Kevin Nishita

“The virus is still active in our community and we all can be exposed,” Dr. Laura Eberhard of Kaiser Permanente San Rafael said in the county’s statement. “With the holidays approaching, getting a COVID-19 booster will allow us to safely spend time with friends and loved ones.”

While Marin boasts one of the highest vaccination rates in the state, with 95% of seniors fully vaccinated, only 25% of residents 65 and older have received a booster shot. The county has set a goal for at least half of the county’s seniors to receive their booster in the next month.

As of Tuesday, boosters are available for those who received the Pfizer vaccine more than six months ago. The FDA is expected to discuss authorizing boosters for recipients of the Moderna and Johnson & Johnson vaccines in the coming days, with health officials saying they would be prepared to expand vaccine offerings once authorization is granted.

Along with seniors, people 18 and older who live in long term care settings, have underlying medical conditions, along with those who live or work in “high-risk” settings are eligible for boosters, according to the Centers for Disease Control.

MORE NEWS: Warriors End Suns’ Win Streak at 18 With 118-96 Victory

Patients eligible for a booster shot can find vaccination locations by visiting GetVaccinatedMarin.org.