Vaccination schedule for children in Singapore

Age - Vaccine given

At birth - BCG & Hepatitis B
1 month - Hep B (2nd dose)
3 months - DTP (i.e diptheria/tetanus/pertussis) & Polio
4 months - DTP & Polio (2nd dose)
5 months - DTP & Polio (3rd dose)
6 months - Hep B (3rd dose)
15 months - MMR (i.e measles/mumps/rubella)
18 months - DTP & Polio (booster dose)
6 years - DT (without pertussis) & Polio (2nd booster)
12 years - DT, Polio (3rd booster) & MMR (2nd dose)

Now, here are some prominent problems associated with these vaccines:

Hepatitis B
In 1998, France withdrew the Hep B vaccine because of linkages to multiple sclerosis as well as other immuno- and neurological problems developing in children who received it.

DTP
The DTP vaccine was taken off the shelves in Japan during the 1970s, again, because of adverse reactions to the pertussis component in DTP. A milder form of the vaccine, DTaP was developed instead because the original pertussis component was too strong and caused severe reactions in people who received DTP. The Kitasato Institute states that "Whole-cell vaccine (DTP) is does(sic) not recommended for use in the Japan." DTaP was introduced in the US only in the 1990s. “aP” means “acellular pertussis”.

MMR
There is a suggested linkage between MMR and autism. This is currently a hotly debated topic with politics and egos being thrown around. Watch this space, it's going to be news.

Polio
The polio vaccine has 2 forms, one given by injection, the other orally (i.e drinking it). The oral form has been known to cause polio in some people instead of protecting them.

The issue of thimerosal or mercury in vaccines
Most of these vaccines are produced in vials and in volumes suitable for multiple doses per vial. Now, the problem with such an arrangement was the repeated introduction of the needles (albeit a different needle each time) into the vials, thus increasing the likelihood of contamination. So to overcome this problem of contamination, a chemical is put into such vaccines. This chemical is thimerosal, which is a form of mercury. So everytime a shot given, mercury is injected into the body along with the vaccine.