Our blood has various types of cells Red blood cells and different types of white blood cells(Neutrophils, lymphocytes, monocytes, basophills) the relative percentage of which changes as a reaction to any infection. So these are just indicators of how our body responds to infection. The response is different for bacterial vs viral infections. Neutrophils increase in early bacterial and viral illess. Lymphocytes in viral infections predominantly. If the child is better already then these tests don't matter.