Hi! Nothing to worry. During change of seasosn, fever is quite a common condition. In fact, fever is body’s natural reaction to fight against an infection. Though it is quite common, it should not be taken lightly.
Viral fevers are contagious and they just transmit from one person to other. In your case, pre-schoolers are prone to getting viral infections. As their immune system is not so strong, these kids might get from their school.
Do not send the kid to school till he recovers completely.