Take the proper precautions and have your children vaccinated before your travels or to prevent infection from exposure at school.
Great Kids Pediatrics recommends influenza vaccine for all patients 6 months and above. Especially if your child has a long-term health problem like asthma, heart or kidney disease, immune system problems, diabetes or blood disorders you should consider an immunization for your child. If your child has a sibling less than 6 months of age, it is also highly recommended to have the older child immunized.
More information on the importance of getting your flu shots available at: https://www.healthychildren.org/English/safety-prevention/immunizations/Pages/Preventing-the-Flu-Resources-for-Parents-Child-Care-Providers.aspx