Over 300 local students stayed home from school Tuesday.
Lambton Public Health Supervisor Erin Courtney says the health unit has not yet received updated immunization records or proof of exemption for 346 elementary and secondary students.
Students will be suspended until those records are provided.
Records include immunizations for diphtheria, tetanus, polio, mumps, rubella and measles.
Children born in 2010 or later also require immunizations for meningitis, whooping cough and chickenpox.
Parents can contact Lambton Public Health via e-mail, fax, phone or in person.