E.g. if a woman has a tetanus shot, why does the kid need one? If she has an mmr shot, why does her child need to get one? If the lady also has a shot immunizing herself from chicken-pox, why isn’t the child also immune from chicken-pox?
Wouldn’t the child be immune from the diseases/ sicknesses that the mother already got her shots for?
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Antibodies are produced in response to a memory stimulus. The original stimulus that programmed a cell to make an antibody is not passed on, and neither is the cell that makes antibodies, however some types of antibodies very much do pass on to the kid (until they degrade).
Since no one is diving into antibodies I will try to. There are 5 types of antibodies (immunoglobulins, Ig) based on their shape (A, D, E, G, and M). IgD, IgE, and IgG are all monomers, meaning they are made with one Y shaped protein. They differ by what makes the base of the Y. IgA is a dimer of two Y shapes connected by their bases. IgM is a pentamer of 5 Y shapes connected at their bases. This size is the large determinant of what passes through the placenta. IgM can not pass through the placenta or breast milk as it is too large. IgA can pass through some breast milk, and also passes in and out of our GI tract to attack invaders. IgG ABSOLUTELY can pass through the placenta and other structures and it is the primary antibody produced after exposures to foreign proteins/sugars through serial infection (I say serial since IgM is primarily produced on first infection, since its size makes it best for finding stuff) or immunizations. I’m not sure if IgE passes but it largely regulates our response to allergens and parasitic infection. It may be that it is often bound to surfaces, but I would guess it can pass on. No one really knows what IgD does but it is only found on the surface of the cells that produce antibody so it would not pass and if it did we wouldn’t know what it does.
That being said each of these antibodies have a half life of 3-4 weeks, meaning half of those proteins are degraded within a month! So even though the antibody can be passed from the mother (via placenta during gestation, or breast milk after birth) it will degrade over time and be useless. In fact when looking for antibody deficiencies you don’t even bother measuring the IgG for a newborn under 6 months since you can’t tell which came from the mom or is produced by the baby. Since the mother passes on some of her made antibodies, it can take months or up to years to discover an antibody deficiency in a baby/child.
Also I noted that IgG is the primary attacker. Some IgG is made to target red blood cells (via accidental exposure to blood, or via germs in our gut that look a lot like blood cell surface proteins). This can cause the fetus to be attacked by the mother, leading to miscarriage. To prevent this, we give Rhogam. I can explain how that works which is a surprisingly backwards solution but I hope this helps.
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