In accordance with the Texas Department of Health immunization schedule, recommendations are adopted by the Texas Board of Health and published in the Texas Register annually, a child or student shall show acceptable evidence of vaccination prior to entry, attendance, or transfer to a child care facility or public or private elementary or secondary school, or institution of higher education. 

https://www.saisd.org/Departments/Health%20Services/Immunizations.asp

ImmunizationsTexas law allows (a) physicians to write medical exemption statements which clearly state a medical reason exists and the person cannot receive specific vaccines, and (b) parents/guardians to choose an exemption from immunization requirements for reasons of conscience, including a religious belief. The law does not allow parents/guardians to elect an exemption simply because of inconvenience (for example, a record is lost or incomplete and it is too much trouble to go to a physician or clinic to correct the problem). Schools should maintain an up-to-date list of students with exemptions, so they may be excluded in times of emergency or epidemic declared by the commissioner of public health.

Instructions for requesting the official exemption affidavit that must be signed by parents/guardians choosing the exemption for reasons of conscience, including a religious belief, can be found on the Exemption Information page of this website. Original Exemption Affidavit must be completed and submitted to the school.

For children claiming medical exemptions, a written statement by the physician must be submitted to the school. Unless it is written in the statement that a lifelong condition exists, the exemption statement is valid for only one year from the date signed by the physician. More information regarding medical exemptions can be found on the Exemption Information page of this website. Original Exemption Affidavit must be completed and submitted to the school.

https://www.dshs.texas.gov/immunize/school/school-requirements.aspx