The long-awaited COVID-19 vaccinations for children ages 6 months to 5 years old became available in San Mateo County this week, San Mateo County Health leaders said in an announcement last week.

The Food and Drug Administration authorized COVID-19 vaccines for children on June 17, and the CDC approved the emergency use of the Pfizer-BioNTech and Moderna vaccines the next day.

The county has been preparing to distribute the vaccines for weeks and was ready to roll as soon as the CDC cleared the way, they said. The shots are administered to children under age 5 at San Mateo Medical Center and at small-scale clinics, but not at county-sponsored shot clinics, Dr. Anand Chabra, county health COVID-19 mass vaccination section chief, told the San Mateo County Board of Supervisors on June 14.

The shots are also available through local clinics at Palo Alto Medical Foundation and Stanford.

In Santa Clara County, health leaders said during a June 17 news conference that the shots will be available at county-sponsored clinics and through local health care providers and pediatricians' offices.

While the vaccines might initially roll out slowly, Santa Clara County expects to eventually be able to provide 1,000 per day, Dr. Ahmad Kamal, COVID-19 director of health care preparedness for the county, said.

The Pfizer-BioNTech and Moderna vaccines come in lower doses than those given to older children and adults, Kamal said. Children receive a three-shot series of 3-microgram doses of the Pfizer vaccine or one-quarter of the adult dose of the Moderna vaccine in a two-shot series. Both are equally safe and effective, he said.

There are 100,000 children in the county in the 6-month to 5-year age group, and the health leaders urged parents to vaccinate their small children. While children tend to weather illnesses better than older adults, there are still considerable risks to not being vaccinated against COVID-19, the health leaders said.

Nationally, those under age 5 have had the highest rates of hospitalization among children. More than 400 in that age group have died, including one child in Santa Clara County, Dr. Sara Cody, county health officer, said.

Dr. Sarah Rudman, county assistant health officer and mother to a 2-year-old child, said she was surprised to learn that two-thirds of young children who contracted COVID-19 were hospitalized, and up to 5% of children who have had COVID-19 might have long-term effects.

"I'm so relieved to be able to vaccinate my child," she said.

Getting small children to wear a mask or socially distance is a difficult task; having the added layer of vaccine protection so that children don't get sick relieves families of the burden of extra work. "It's a game-changer," she said.

For parents who might be concerned about the vaccine's safety and whether they should immunize their children, Rudman said as a doctor and a parent, she has reviewed the studies for safety and efficacy.

"The vaccines are incredibly safe," she said, adding that researchers ran multiple trials for months that involved thousands of children. There also is more than a year's worth of data on millions of people in other age groups that has proven the vaccines to be safe and effective, she said.

Rudman said she expected there would be minor side effects. Children who received the vaccinations could be fussy and sleepy and might not eat as much.

"But we're not seeing scary side effects" that were a concern, she said.

The data shows the level of protection in terms of antibodies is similar to what is seen in older children and adults.

Wastewater surveillance data, which tracks the presence and quantity of SARS-CoV-2 virus in the county, is showing the virus is nearly as rampant as it was at the height of the omicron surge, Cody said. "That data generally tracks well with case data," she said.

The largest of the county's four sewersheds, in San Jose, looks as though the levels of virus are just starting to come down. The other sewersheds are "a little bumpy," but might also be starting to edge lower, she said.

Countywide for the entire population, the vaccination rate is at 86%; 70% of people who are eligible for boosters have received at least one shot, Cody said.