HOUSTON, Texas (KTRK) -- Just days before school starts for the year, volunteers in Spring Branch are offering free vaccinations.The Spring Branch Family Development Center is teaming up with Spring Branch ISD to offer free vaccinations and health services to families on Saturday, Aug. 10. The event starts at 8 a.m., but many families in the past have lined up the night before."Historically, we have become the largest single-day immunization drive in Houston," explained Executive Director Ricardo Barnes. "Last year, we immunized 1,500 kids and 240 parents."The center opened 18 years ago to serve the traditionally under-served area around it.Some 6,000 residents live within walking distance, and many of them have no transportation or English language skills."Without the immunization records up to date, they cannot attend school," Barnes said. "So, we want to make sure the kids are able to start on the first day of school.'