Unvaccinated contacts are not at risk of becoming seriously ill with the weakened flu vaccine virus, either through being in the same room where flu vaccine has been given, or by being in contact with a recently vaccinated pupil. No ‘mist’ of vaccine virus escapes into the air and therefore, there is no need for any child or staff member to be excluded from school during the period when the vaccine is being offered or in the following days.
The tiny number of children who are extremely immunocompromised (for example those who have just had a bone marrow transplant), are already advised not to attend school because of the much higher risk of contact with other infections that spread in schools. Although vaccinated children do shed vaccine virus for a few days after vaccination, the virus is less able to spread from person to person than the natural infection.
The amount of virus shed is normally below that needed to spread infection to others and the virus does not survive for long outside of the body. This is in contrast to natural flu infection, which spreads easily during the flu season. In schools where vaccine is being offered therefore, the overall risk of contact with influenza viruses is massively reduced by having most children vaccinated.