Vitamin D is my top winter tool. Start supplements before the days shorten. When illness starts, boost vitamin D and vitamin C. Elderberry, quercetin, fish oil, and local honey help many families I treat. Steam, saline sprays, and humidifiers ease airways. Use bronchodilators and nebulized saline when wheeze appears. At home, reduce allergens. Control humidity to limit mold. Wash linens often and...