Vaccination Schedule

Can you help me understand the vaccination schedule?

The South African vaccination schedule is as follows:

At Birth: BCG and OPV
At six weeks: OPV, DTacP-Hib, and Hepatitis B
At ten weeks: OPV, DTacP-Hib, and Hepatitis B
At 14 weeks: OPV, DTacP-Hib, and Hepatitis B
At nine months: Measles
At twelve months: Hepatitis A pediatric and Varicella
At fifteen months: MMR
At 18 months: OPV, DTacP-Hib, Hepatitis A pediatric
At five years: OPV, MMR, and DT
At twelve years: MMR

Key:
BCG – Tuberculosis
OPV – Polio
DTacP-Hib – Diptheria, Tetanus, Pertussis and Influenza
Varicella (Chickenpox)
MMR ( Measles, Mumps, and Rubella)
DT – Tetanus and Diptheria