By Marissa Perlman

ROSEVILLE (CBS13) – In Placer County, The Grounds clinic in Roseville is opening up eligibility to anyone 16 and up, just days before the state is set to do the same.

The county says the 50-64 age group wasn’t filling up appointments and they wanted to put the vaccines to good use.

READ MORE: Citrus Heights Police Investigating Saturday Night Homicide

But Placer County Public Health leaders say that’s normal, calling it the “ebb and flow” of what they’ve seen throughout the vaccination process.

“We have an initial big rush and then we see appointments sitting. That’s been our trigger to know we need to move on,” said Katie Combs- Prichard with Placer County Public Health.

The website Vaccine Spotter tracks open appointments, based on where you live, and as of Monday, there’s wide availability across the region.

For months, supply wasn’t meeting demand, but now there’s little wait, and more options for those that want them.

“There’s an imbalance for where there’s demand and adequate supply, and where there’s less demand and oversupply,” said Dr. Jeffrey Klausner, an Infectious Disease Expert with USC.

READ MORE: Pedestrian Dies After Being Hit By Car In Sacramento

He says there is vaccine hesitancy from some groups across the state, pointing to studies that say those under 45 and Republican men are less likely to get the shot. But he says access will make a bigger impact, overall.

“The biggest factor when it comes to getting high vaccination rates is access, and having a variety of different strategies, mega pods, drive up- vaccination programs, in different, targeted communities,” he said.

But if the state does see vaccine hesitancy, how will herd immunity be impacted?

Dr. Klausner says in some pockets of the population it may be harder to achieve.

“To achieve full population herd immunity — that ultimately will result in no new infections. That may take a lot of time, or that won’t happen at all,” he said.

At least 70 to 85 percent of the population needs to get vaccinated in order to reach herd immunity.

MORE NEWS: Fawn Fire Grows To 8,537 Acres, 35% Containment

Dr. Klausner says about one-third of people are immune or will be immune to COVID because they already have had the virus. He says that will help overall herd immunity.

Marissa Perlman