My son is having borderline autism. He was diagnosed at 3.5 years age. Now he is 7 years. He had not taken any vaccination for past 2 years due to the fear of some preservation chemical in vaccines which causes autism. Can the pending dose of vaccinations be given at a later stage? His physique is also very very thin. Even if he eats all kinds of food in ample quantity but he doesn't gain weight at all. Kindly advice.