Why are vaccinations given at such a young age?

Question

Babies receive their first vaccine shot before 3 months old when they still rely on passive immunity from mother's milk. In the first year babies have little ability to fight off anything because of the lack of maturity of the immune system. How then can they build immunity from vaccinations at such a young age?

Answer 1

They're given at such a young age to prevent infections that can make children sick, some of which can make children die, at such a young age.  Yes, there is passive immunity from mother's milk that is thought to help protect the breastfed, but that isn't the main source of immunity.  Children who can't be breastfed or (like me) from a generation that mostly wasn't breasftfed develop perfectly good immunities early on.  A baby in its first year actually has a reasonably robust immune system, and they're acquiring immunity to all sorts of things as they explore the world by tasting it in ways that sometimes worry us parents, especially first time around.  The vaccines, whether it's inactivated pathogens or recombinant proteins, actually do stimulate an immune response at this age, and would not be used otherwise.

As you point out, nothing medical is risk-free, and vaccines are used because the benefits greatly outweigh the risks.  There would obviously be no benefit if babies were unable to mount an immune response, and I think this is the source of your confusion - they can do so, in reality.  Many pediatricians will put vaccinations off for a few months or give one at a time at the request of the parents, but that's an attempt to minimize side effects or discomfort or to please the parent, while figuring particular infections aren't likely enough to make this dangerous.  It's not because the immune system isn't ready to respond to the vaccine.

Answer 2

Clearly you don't understand how a vaccination works.  A vaccination creates the same immune response as catching the disease without the actual risk of symptoms and death.  This means that a person who actually gets the disease has the same immunities later in life as a person who received the vaccination instead.

Answer 3

i m no expert but i believe it is because your immune systume cant block it out

Answer 4

Maternal milk only conta ins antibody mediated defenses. It doesn't do anything for T-cells and other aspects of the adaptive immune system. When they say that infants do not have a 'fully working' immune system, they mean that because they have not been exposed to enough antigens in the environment to develop a good library of adaptive immune response - their own antibodies and T-cells.

The coverage by the mother's antibodies allows the infant's immune system to be exposed to the environment and develop it's own adaptive defenses, without dying in the weeklong lag it takes to generate an antibody from an uncontrolled infection.

When they say 'not fully working', again, they are generally referring to the lack of self-generated antibodies and active T-cells. The immune response works completely normal. Because the response works normally, the vaccines can be given. Essentially a vaccine is 'maturing' the immune system against that one disease, while still protected by the mother's milk.

And remember, not all women breast feed, or breast feed for as long as anyone else.

And immunology is one of the scariest and intimidating bio-sciences. Seriously, I have notes from these courses that make me want to wet myself.