When it comes to children, my preferred essential oil is thyme linalool
(Not to be confused with thymol). It is a powerful yet gentle essential oil
that is effective against many types of infection (bacterial, fungal,
parasitic, viral).

Therefore, it helps the body to eliminate microbes that weaken the
immune system (increasing vulnerability to illness). You can take it orally (1
drop suffices): prepare to grimace! For young children, it works just as well
when rubbed on the throat or the soles of the feet. Warning: It is not
recommended to administer thyme linalool essential oil to children under 3
years of age.

Using Massage to Boost your Child’s Immune System: 

According to my friend, who has been a massage therapist for over 17
years, the most effective and commonly used massage technique to calm
hyperactive children is Swedish “effleurage” (light, skimming touch) along the
spine. With both hands, make circular motions from the upper to lower back.
This performs a lymphatic drainage that simultaneously stimulates the immune
system while calming the nervous system. By adding lavender or chamomile oil to
your hands or oil the calming effect will be enhanced. Sharing this bedtime
ritual with your child will help them sleep and is easily done while they are
sitting on their knees with their head resting on your lap. They will surely love
it.