Scavenger hunts and blow-up animals greeted children at some of California’s vaccination sites Wednesday as children aged 5 to 11 got their first COVID-19 shots a day after the federal government approved kid-size doses of the vaccinations.

As part of an ambitious plan to offer coronavirus vaccinations to California’s 3.5 million children in that age group, the state intends to offer the vaccines at locations including school clinics, pharmacies, pediatrician offices and county sites, many of which will launch in the coming days. Health officials said they are expecting 1.2 million initial doses of the pediatric vaccine.

Santa Clara County, the home of Silicon Valley, starting doling out shots early Wednesday, and appointments quickly booked up. The county expects to receive about 55,000 doses this week and will open additional clinics at 80 school sites and send out mobile vaccine teams to low-income neighborhoods.

“This is an important step in protecting our children and our community, providing relief for families, and creating an additional level of protection to maintain in-person learning for our schools,” Santa Clara Health Officer Sara Cody said in a statement. Many of Santa Clara’s county sites were decorated with kid-friendly motifs like animals and included games like scavenger hunts, while others handed out coloring books and prizes, officials said.

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Pop-up clinics in Los Angeles County also started giving doses to children on Wednesday, the county department of health said. The county is the nation’s most populous with 10 million residents, including about 900,000 children between 5 and 11 years old.

California has one of the highest vaccination rates in the country, and has also had some of the strictest masking and vaccination requirements, but new cases and hospitalizations have plateaued recently after a steady two-month decline that saw California boast the nation’s lowest infection rate. State models show a gradual increase in hospitalizations in the next month as colder weather and holidays drive people inside.

Gov. Gavin Newsom announced last month that California would have the nation’s first coronavirus vaccine mandate for schoolchildren — about 6.7 million public and private school students in the nation’s most populous state — once the federal government has given final approval for the shots. The mandate will be phased in and will likely not take full effect until next July.

Newsom hailed the new availability Wednesday, saying the pandemic “has taken a heavy toll on the well-being of our kids.”

Also Read: Turning point in battle, says Biden after CDC approves Pfizer for kids

Kid-sized doses of the Pfizer-BioNTech vaccine cleared two final hurdles Tuesday: a recommendation from advisers with the Centers for Disease Control and Prevention, followed by a green light from Dr. Rochelle Walensky, director of the CDC.

The federal government has promised enough vaccine to protect the nation’s 28 million kids in this age group, with many enthusiastic parents rushing to get their younger children inoculated before the holiday season.

Some Kaiser Permanente hospitals in Northern California will start offering the Pfizer COVID-19 vaccine to children as soon as Monday, officials said.

“Now parents can kind of take a collective sigh of relief,” said Dr. Keedra McNeill, a Kaiser pediatrician and mother of two daughters ages 6 and 8.

Kaiser, one of the nation’s largest health care providers, participated in the Pfizer pediatric vaccine trial in Northern California, which found the vaccine for children ages 5 to 11 had an efficacy rate of over 90%, said Dr. Nicola Klein, director of the chain’s vaccine study center.

“We’ve been doing clinical trials for 30 years and I feel very comfortable and confident that the clinical trials that were done for these children, children ages 5 to 11 were … done with the same high-quality standards that have been done for all the other vaccines that we’ve been studying for the last 30 years,” she said.

Many counties planned to begin their rollout at mass vaccination sites this weekend.

In Marin County, officials expect to be able to vaccinate 1,000 children per day at rotating sites, while Contra Costa County plans to open county clinics Saturday to start doling out the 20,000 doses of the pediatric vaccine expected this week.

“I know a lot of parents have been waiting a long time to be able to get their younger kids vaccinated,” said Diane Burgis, chair of the Contra Costa County Board of Supervisors. “We’re almost there. If everything goes right, parents will be able to get their children fully vaccinated before the winter holidays.”