(HARRIS: So Just relax back...)
Karen Harris is the school nurse at Nevada Union High School in Grass Valley.
She's been working through the summer to get 7th through 12th graders up to date on their whooping cough vaccine before school starts.
(HARRIS: A little bit of a stick….)
At this free booster shot clinic Friday morning, Harris says the district has 6-700 more students to account for.
HARRIS: Pertussis tends to peak in the fall, August, September, October, so we really want them to be vaccinated for that reason.
Families can opt out of the vaccine because of personal belief.
More than 17% of kindergarteners in this county went without vaccines for that reason last year - the highest rate in the state.
But Harris says a lack of widespread immunization during a whooping cough outbreak concerns her.
HARRIS: The people it's going to affect, are those newborns their first two months of life, sickly young young children. Really we're looking at herd immunity… protecting all of us.
Doctor Karen Milman is public health officer of Nevada County.
She says the low vaccination rates are the result of a perception of health risks from the shots.
MILMAN: We have people who come up here for the healthy lifestyle so they want the organic food, want to live away from air pollution… Unfortunately they don't see immunization as healthy and as beneficial as immunizations actually are.
Grass Valley School District starts back up August 17th.
They have 30 days after school starts to get or waive the shot.