Original Articles By Dr. Lavin Featuring Expert Advice & Information about Pediatric Health Issues that you Care the Most About

Back to School Primer: A Reminder of Common Illnesses at School

By Dr. Arthur Lavin

Over the next 3-4 weeks, all of America’s children will be returning to school.

We will be writing about the work they face, but in this post, we offer a few links to past detailed accounts of three of the most common infections that soar once we have our children sit in a room with 1-3 dozen other kids for 6-8 hours, 5 days a week.

This gathering of children boosts the number of infections because germs operate on the mathematics of the chain reaction.  Not all interactions chain react.

For example, going to work leads to an accumulation of pay, but that is a simple addition of money to our accounts.  If this week you make $100, and you don’t get a raise and don’t change your work, you will make $100 the next week, it doesn’t naturally increase, sadly.

But infections don’t work that way.  If you have a cold, you could infect 10 people easily over the course of that cold.  If each of the 10 people who catch your cold infect 10 others, now 100 are infected.  If each of them infect 10, now 1,000 people get infected.   This is an exponential pattern of growth called a chain reaction because each link in the chain explodes the numbers.   If this pattern of spread went on uninterrupted, then everyone in the world would catch that cold in a few weeks, but that doesn’t happen, why not?

The main reason is that viruses fail a lot.   We breathe in about 5 million viruses, every day!  But we tend to have about 8 viral infections across an entire year.  That means only 1 in 225 million viruses that we breathe in cause an illness.  That’s pretty amazing.  Also, some kids in the class will have had that virus already and will never get sick from that cold.

So putting that altogether, going to school vastly increases exposure to viruses and strep, and infections grown by chain reaction, not uncontrolled chain reaction, but chain reaction nonetheless.  So when school starts, many illnesses really roar.

Here is a sentence or two on three such illnesses, with links to  more detailed discussion about them:


Colds happen in all seasons, but they really ramp up once school convenes.  We see it every year.  There are a handful of colds seen in the summer, but by mid-September colds are really raging, and we see many, many every day until school is out.  Colds are the most common of illnesses, hence common cold, and if they remain colds (that is, do not turn into ear infections or other infections), are harmless, meaning once you recover you are as healthy as before you got sick.  Schools tend to be far more tolerant of colds than the other two illnesses listed before.  We don’t tend to hear about schools sending home notes to inform parents that their child has been exposed to another child in the classroom with a cold.

Given the rush of colds about to descend on all families, you may find more details about colds of interest in our previous articles:
How Long Do Colds Last?
The ABC’s of Vitamins Failing to Help with Colds: Time to add the D
The Wonderful Story of Linus Pauling, Vitamins, and Colds
‘Tis the Season, Not the Temperature: The Cold Does Not Cause Colds


Pink Eye

Pink eye refers to conditions in which the whites of the eyes are reddened from inflammation.   Aside for itchy eyes from allergies, the vast majority of pink eye is viral, and not any different from having a cold.  But schools have a special aversion, bordering on panic, about this infection.  Despite all the worries, viral pink eye is not terribly contagious and totally harmless.

Given that this is a viral illness, it really does become much more common when school starts.

Take a look here for further details about pink eye:
The Eyes Have It: Three Real Causes of Pink Eye, and the Mythic Pink Eye that Never Was but is Always Feared



Strep, as noted in a post from this summer (liinnk) is now seen year round, but like colds and pink eye, it is far, far, far more common once we pack together in school.

More than any other infection, strep commands the now familiar note home.  Schools feel a deep obligation to send a note home duly informing every parents in a classroom that a child in that class, if they are known to have strep, has exposed all the children.  We find this a rather useless action for the following interesting reasons:

  1. A study of American classrooms swabbed the throats of every school child every school day for many months, most of the school year.  They found that at any point in time, every classroom had 10% of the class positive for strep, whether the children had symptoms or not.
  2. This makes much sense because if you looked at every child in America who was infected with strep right now, you would find 1/3 had a sore throat, 1/3 had cold symptoms but no sore throat, and 1/3 felt fine with no symptoms at all.   That means 2/3 of kids infected with strep have no symptoms suggesting they have strep and never get diagnosed or treated.
  3. With all this in mind, if it truly of any value to inform you that your child has been exposed to strep on any given day, the school would need to send their strep exposure notice home to you every school day, because every child is exposed to strep in school every day.

These points remind us that exposure is truly a constant part of life, and matters so much less than actually being ill, which as we have noted, happens infrequently after exposure, even to someone contagious.

Strep has all sorts of interesting properties, for more detail on them, here are a few of our previous articles on them:
Summer Strep Throat- Why has Winter Invaded Summer?
On the Best Timing to get Tested for Strep Throat



  1. School opens soon, next week for many.  As we have our children return to sitting with dozen(s) of other children in a room for many hours a day, viral and strep infections will start roaring as they do every year by mid-September.
  2. Exposure to viruses and strep is, in fact, a daily, constant event, and therefore one day is not really much different than another, even if one or more children are discovered to have strep or a virus.  No about a contagious child or not, there are contagious children in every classroom every day.
  3. Colds, strep, and pink eye are very harmless infections, children all get them, and unless a very odd and rare complication occurs, recover without harm at all.

So we hope the return for school goes well, we remain available to help you if these illnesses appear and raise concern.

To your health,
Dr. Arthur Lavin


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