FAIRFIELD (CBS13) — A number of teachers in the Travis Unified School District were kept out of their classrooms on Wednesday after school officials learned their clearances had expired.

Initially it was discovered that 15 teachers had expired clearances. Three were able to take care of the issue quickly

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According to the district at noon on Wednesday, 12 teachers were waiting for TB skin tests to come back.

Tuberculosis is an infectious disease, and some types can be contagious.

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The district says it maintains records for teachers staff and TB data and isn’t sure how It missed the expiration dates for the teachers

Twelve substitutes were hired at a cost of more than $1,300 a day.

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State law says teachers cannot be in a classroom if a TB clearance test has expired.Most of the teachers have been cleared with only three remaining out but the district tells me 80 employees will have their clearances expire next month.