Your child need proper set of exercises as well as proper orthotics to correct the angle which needs to be progressive in nature.
So please visit a good physiotherapist as well as occupational therapist to manage it properly.
Its. Good That the problem was noticed early. As the child Grows the Angle would probably increase and would cause more harm which could result in decreased lung capacity, reduced and changed heart functions.
Two options you can go with now.
a) Rehabilitative .
Minimal Risk involved at present. long duration, effective.
Uses customized jackets ( to treat scoliosis) and bony Traction (to treat kyphosis) and post few weeks going for a good rehabilitation involving manual stretchings by (occupational Therapist / physiotherapist) will do the job.
People involved (TEAM) : You and your Child, Orthopaedic surgeon (major Function3), orthotist (major Function1), Occupational therapist / Physiotherapist.(major Function2)
Much Risk as Surgery is Complicated at present, Quicker, Effective (if successful) .
for this method i will recommend you choose a surgeon with a good reputation and experience (not only on basis of Position the surgeon holds makes him/ her best surgeon among lot) do talk to few of his/her cases before finalizing the surgeon.
TEAM would be same instead major function would be of the Surgeon and then the therapist (rehab personnel) and then orthotist.
Decide and Consult as soon as possible , it is good to take decision soon.
DO NOT LET YOUR CHILD TAKE / SIT / LIE DOWN IN INAPPROPRIATE POSTURES YOU MUST USE PILLOWS AND CUSHIONS TO CORRECT POSTURE (CONSULT YOUR THERAPIST FOR THE SAME). STAY HEALTHY