Welcome to our Community! You are our first member from Vietnam.
So yes, the good news is that IVIG is an excellent preventive therapy for SCLS, including in children, but the bad news is that IVIG is very expensive to produce (from blood donations), and because SCLS is a fairly newly diagnosed illness, patients, caregivers and medical doctors must obtain IVIG for SCLS on a case-by-case, exceptional basis from their private or government-run insurance programs. This is true even in the United States, where I live.
I have just sent you several, recent scientific articles on IVIG for SCLS, including for children, which you can use to show to your doctors and insurance company that IVIG for SCLS is no longer an experimental treatment but, rather, the most recommended and effective treatment available.
I have some suggestions. First, your government insurance plan must have some appeal process, so you should appeal every denial. In case you haven't done this already, you should get the ICU doctor who treated and diagnosed your son to write a letter on hospital stationery supporting your appeal and your son's treatment plan. Second, you should submit the articles I have just sent you to the government insurance company. Third, you should make an appointment with Dr. Vu Chi Dung, head of the department of endocrinology, medical genetics and metabolism in Hanoi's National Hospital of Pediatrics (18/879 La Thành, Láng Thượng, Đống Đa) because he is your country's leader in terms of rare diseases, especially in children. If he agrees with your son's diagnosis, and he reads the scientific articles I have sent you, I am sure that he too will write a letter -- or do more than that -- to support your appeal. Another person to speak with there is Tran Minh Dien, deputy director of the NHP. I read that the NHP even has a patient support group called (in English) the Rare Disease Patient Club, so you should join it to find out what others have done to obtain treatment for their illnesses.
Trust me, many of us -- including me -- have had to work very hard to get our treatments, so we understand your situation even though we don't live in Vietnam. Your son is actually very lucky to live in Hanoi, and not in other cities -- never mind in rural areas -- of Vietnam.
Let us know what happens,