U can give Syp bevon / a to z 5 ml once a day for 5 yrs old kid 7.5 ml once a day for 9 yr old kid Also vitamin c is very necessary for immunity boosting up so you have to include at least one fruit from banana papaya mango orange in children's diet everyday.. You can also make some herbal tea made from mixture of fudina Tulsi ajma Ginger turmeric jaggery lemon in water..

Good morning You can start with any multivitamin syrup like zincovit, Ato Z, bevon, Ferroglobin B12 etc. As you have not mentioned weight of the kids you can start with 5 ml once a day (syrup not drop) for both. For covid situation rather it is better to have a healthy and nutritious diet and follow strict hand hygiene, use mask and keep social distancing. Thanks