If the reason day care or kindergarten children get sick a lot is because their immune system is sti

It makes sense that children who are for the first time being exposed to many germs will get sick a lot and that’s why it is expected for many months that the child will get sick at very high frequency.

It is said that eventually their immune system develops and they stop having that problem within a couple years.
If that is the case, then why do parents, who by extension, already have advanced immune systems that developed decades ago when they were children and are therefore supposed to already be much less prone, lament about getting sick with the child after the child gets sick from day care or kindergarten and passes the germs to the parent? If that’s the case, then how is the parent’s immune system any better? In fact, many say that they fight off the illnesses even slower than their child.

So I’m not seeing how, as an adult, I benefitted from getting sick a lot in day care and kidnergarten, if my immune system is likely no better off than theirs.
If anything, the children’s seem to be better. Most adults are much more cautious about hygiene and spreading of germs. Children on the other hand to lots of gross things and still a high percentage of the time, they don’t get sick. Meanwhile I stopped eating off the floor many years ago. At the same time, for many years, I have seldom gotten sick from germs at 21. So clearly, my immune system has a decent enough ability (even clean and hygienic people encounter plenty of germs).
Someone resolve this paradox for me. Whose (children’s or adults’) immune systems are on average more capable? And how or why?

“It is said” is often not a good starting point.

I am not a doctor, nor have I researched this, but it seems to me your initial analysis is flawed.

Kids have developing immune systems, which make them more perceptible to illnesses, and they have encountered fewer of the diseases that we can develop an immunity to. But kids also have a lot of behaviours that increase infection risk, such as touching everything, putting things in their mouth, and going to daycare where they interact more closely than adults normally do. I believe it is the latter that is the most responsible for the frequency with which kids get ill.

The majority of the diseases that kids get in kindergarten are diseases that people don’t get immune to, or that steadily develop into new versions, like the flu. So the immune system doesn’t really matter. The parents are getting sick because having a kid in kindergarten means you get exposed to more pathogens than if you don’t have a kid in kindergarten. They also, in my experience, do get sick less often than their kids, but more often than their child-free peers. So their immune system do play a difference.

The main diseases involved are rhinoviruses (“the common cold”), and influenza. We don’t acquire general immunity to them because there are many varieties of rhinovirus, and having one doesn’t protect from the others, and influenza mutates so often that having a previous version doesn’t protect from new ones.

As said, school age kids get sick a lot because (1) they are in close contact with a lot of other kids, (2) they have behaviors that promote contagion, (3) they haven’t yet been exposed to most of the rhinoviruses. Their parents have already been exposed to many rhinoviruses, so they will pick up more than non-parents, but won’t pick up everything their kids get.

You do not develop immunity to strep or bacterial conjunctivitis, which children spread readily due to close contact, and which I got from my kids several times when they brought it home from day care.

Having only been an uncle let me posit two reasons: firstly sympathy - being ill sucks for the child. And secondly, the financial impact - these days both parents work so one parent has to take time off work to care for the sick child with consequent loss of income.

Right, according to Wikipedia there are 160 recognized strains of rhinoviruses. After having caught one, you’d have resistance against it, but no protection against the other 159. if you caught 3 unique strains per year by the time you were fifty you’d have a pretty good chance of fighting off whatever came along, but of course they don’t come one at a time in a neat row like opponents in a kung-fu movie.

Actually, now that I’m close to seventy, I can’t remember the last time I caught a cold, although my school aged grandchildren spend a lot of time being disease vectors. Maybe there’s something to this.

By the time you’re were fifty there would be 160 new strains. There’s a new strain of flu every year.


Rhinoviruses are not flu. As I said, they are what are usually called “the common cold.” Symptoms include a runny nose, congestion, sore throat, sneezing, and coughing, but usually not fever. Influenza (flu) is a different virus. It has similar symptoms to a cold but also includes high fever and exhaustion.

You really notice this if you’re a doctor working with children. The first year or two you not only have a cold most of the time, you often have 2 colds running at the same time. Then it tails off, and when you’re 70 you can tell your adult children not to worry about giving you a cold-- you’ve pretty much had them all.

I always understood it to be that daycares and schools in a geographical reguon had their own “pool”, so at first your kid gets everything and brings home everything, but in time it stabilzes out.

Also, in what age range does our immune system typically fully develop?

Rhinoviruses are indeed not flu, and I don’t think I said they are, but I can see how my wording would cause the reader to misconstrue my point. And my point was that if the flu virus mutates, then other viruses such as rhinovirus probably do too. If you get immunity to any of them there’s always a new one coming along.

Wait, can you really get all the colds?

I thought that the reason you couldn’t become immune to the common cold is that it mutates so quickly. But if there really are just ~160, then couldn’t we cure the common cold with just a bunch of vaccinations?

Producing 160 vaccines would be spectacularly expensive and time consuming. You could probably combine some in a single shot, but you would still probably have to have a lot of injections. An occasional cold is a bother, not normally life-threatening, so it isn’t worth it.

The influenza virus mutates rapidly, but there is usually only one main variant at a time. It’s more serious and can be fatal in some people, which is why it’s worth developing a new vaccine every year.

Actually, they don’t. From this article on “Why haven’t we cured the common cold?”

The approach being taken now is to develop a vaccine effective against 80 different serotypes, but it seems they’re only up to around 50 so far.

One factor is that the rhinoviruses are among the smallest known viruses, while influenza is significantly larger and more complex, which provides more scope for mutating into new forms.


I doubt we really see “fully develop” so much as like everything else, an immune system that actually has to work is more efficient when it encounters an actual pathogen. Maybe a better analogy would be muscle development? (IANAD)

I read some series of articles suggesting the “let your kids get dirty” plan - that if a child’s immune system does not have random bacteria and viruses o practice on, it may instead “look for work” and develop sensitivity to things in newly encounters that are not really diseases, and this is how some allergies come about.

before kids i used to think i had a strong immune system. now i know i was just really good at staying away from people who sneeze directly into my face while reading them stories.

I remember as a resident going on rounds with a wise old (not that old, actually) infectious diseases doc, when a mom and her young child got on the hospital elevator with us. The kid was sneezing, coughing and dripping nonstop.

After the two (mercifully) got off at the next floor, the doc turned to us and said “Ah, a vector.” :eek::slight_smile: