As a sequel to last week’s blog regarding the non-impact of vaccine additives, let’s explore the grand impact of the vaccine itself on the immune system… One of the questions I address most often with my patients’ parents is “Do you think an infant can handle so many shots at once?” The desire to space out vaccines is a strong one for many families – 3 shots just seems like too many for a 2-month-old – especially because combination vaccines are given at this time and the child may be receiving 8 vaccines at a single visit.

So, are there greater side effects associated with getting 8 vaccines versus 1 vaccine at once?

The simple answer is no… but let’s understand why. Each vaccine presents the developing, but not totally naïve, immune system with a certain number of antigens. As discussed last week, the Hepatitis B vaccine in particular, deploys 1 antigen per injection to stimulate the development of antibodies against this virus. Subsequent injections of this vaccine seek to intensify this antibody response, so that if the actual disease enters your child’s bloodstream, he or she can effectively disarm it. How does this compare to the antigen load of a cold, strep throat, food, sucking on fingers, mouthing a toy etc.? The AAP and CDC estimate that each day we are exposed to thousands (not hundreds but thousands) of antigens via the above means.

Per Dr. Paul Offit, pediatrician and infectious disease specialist, ‘Although we now give children more vaccines ,the actual number of antigens they receive has markedly declined. Whereas previously one vaccine, smallpox,contained about 200 antigen proteins per shot, now the 11 routinely recommended vaccines contain fewer than 130 proteins TOTAL.’ We do not routinely give 11 vaccines simultaneously but stagger them as advised by multiple well-orchestrated studies. However, even if a physician was trying to “catch-up” immunize a child, and thus gave 11 vaccines at one time, then approximately 0.1% of the immune system would be temporarily “used up.” This borders on being a non-impact to an infant’s young, although still thriving, immune system.

But if such a small effect, then why do some babies become extremely fussy or run a temperature after vaccine administration? Well, because even though the immune system can handle a much greater onslaught if necessary, an antibody response is still generated for each presenting antigen. Inflammation occurs as disease fighting cells are called to respond, antibodies are generated and the offending agent is destroyed and engulfed. This can make anyone feel a little off. However, the disease never takes hold. Because vaccines are killed or attenuated, the presentation of the foreign material stimulates an immune cascade that inherently cannot be overwhelmed or defeated by a vaccine. But, next time, if the actual pathogen presents itself to the immune system, the child is literally armed and ready.

The take-home point is this: The shots recommended at each visit by the CDC and AAP are recommended for a reason – the antigen exposure of multiple vaccines administered at one time is easily tolerated by an infant’s immune system. They are fighting so many forms of bacteria, viruses, fungi etc. are on a day -to-day basis, that they are more than equipped to manage this metaphorical ‘drop in the bucket’. Even before a baby is born, the immune system is beginning to generate cells that can distinguish foreign from innate. The protective mechanisms are complex and highly developed from the start, but they do need guidance. The questions, as parents, we really need to be asking– What diseases could ravage an infant? What illnesses, although perhaps rare today, could literally debilitate my child? And if there is a vaccine that can prevent one of these dangerous diseases, then please protect my child from it.