The vaccine schedule in 2012 contains several more vaccines but the number of antigens the child is exposed to by the age of two is 315.

"The most important way that parents can protect their children from very serious illnesses is to follow the recommended vaccine schedule," Altmann says.

But that small number is still too many, and some doctors have altered their vaccine schedule.

While effective in protecting against anthrax, the licensed vaccine schedule is not very efficient, involving a cumbersome five (previously six) dose injection series.

This book presents an alternative vaccine schedule alongside that of the American Academy of Pediatrics.

That's why it's important to understand and keep up with your kids' vaccine schedules.

WebMD presents this vaccine schedule, offering basic information about the most common vaccines for adults.

Some veterinarians' recommended vaccine schedules may differ from this.

Doctors say they could also adjust vaccine schedules, monitor indicators of damage to the immune system and offer other care that could improve the children's chances.

All other vaccines may be administered to contacts without alteration to the vaccine schedule, with the exception of the smallpox vaccine.