Kids, Germs and the Flu Vaccine

Last week I was at a public play area with my eleven month old daughter.  Most of the other kids were older and she found them fascinating.  One 22 month old knelt in front of her, excitedly calling to his mother about the baby he had discovered.  After a few moments, he suddenly leaned over and licked her face, cheek to eyebrow.  His mother swooped in with impressive speed and my daughter looked a little forlorn as her new friend was carted away.

The concepts of germs and infection are not something we are born understanding.  The germ theory of disease was not popularized until the late nineteenth century.  For the under five crowd, the entire relationship is fairly abstract.  I have recently started introducing the idea to my three year old.  Our conversations usually go something like this:

"Honey, don't put that in your mouth.  That's yucky."

"Why is it yucky?"

"Because there might be germs on it that could make you sick."

"Oh... No, I don't see any germs."

My most recent blog post featured a little girl with influenza whose mother wanted to know if it was too late for her other children to get the flu vaccine.  My dad was not impressed that I did not answer the question.  So here goes.  The short answer is yes and no.

Influenza virus is primarily spread through respiratory droplets.  These are the particles of mucous or saliva ejected when someone coughs or sneezes.  They are fairly heavy and usually do not travel more then three feet.  Influenza virus can also survive on a hard surface for up to eight hours.  People can be contagious one to two days before they start showing symptoms and are most contagious for the first three to five days of illness.

Based solely on my observations (and not data) it is my impression that small children are just as likely to use their hands and sleeves as they are to use a tissue to wipe their noses.  Their hand washing skills leave something to be desired (like soap). Siblings hug and spit and snuggle and fight.  They play with the same toys, read the same books, and color with the same markers.  Small children are known to use someone else's spoon or straw or toothbrush without a second thought.  They lick other people's faces and they do not see any germs.  In a family where one child has been contagious for over two days, there is a good chance that the other children are already infected.   

The flu vaccine takes up to two weeks to take effect. Meaning, after receiving the influenza vaccine, it takes your body about two weeks to develop the antibodies that will protect against the actual influenza virus.  If you have not gotten your flu vaccine and your body is invaded by the influenza virus, getting the vaccine at that point will not protect you from getting sick.

That being said, each flu season features multiple strains of influenza.  The influenza vaccine usually protects against 3 or 4 different kinds of influenza virus.  If you have the flu, you will develop antibodies to the strain of virus you were infected with, not the other kinds that are out there.  Getting the flu vaccine, even after you have had the flu, can protect you against the other strains of flu virus.

It is never too late to get the flu vaccine but it is most beneficial if given prior to actual infection.

Is It Too Late To Get the Flu Shot?

February of my intern year in residency I was assigned to the Emergency Department.  The season of respiratory illnesses was in full swing.  Before each shift, I would wade through a packed waiting room.  The air in the ER was buzzing, the rooms were full, and a rack of charts belonging to patients yet to be seen greeted me.  Influenza, respiratory syncytial virus and flu-like illness were diagnoses I made daily.

On a bed in the hallway, a five year old girl sat with her mother.  She had a fever, a runny nose and was generally feeling miserable.  I ran through the usual history taking, narrowing the diagnosis and checking for red flags.  “Did she get her flu shot this year?”  I asked. 

“Oh, we never get a flu shot,” the mother stated, proudly.

“We recommend that all kids get one every year,” the words came out automatically at this point in the month.  I felt like a recording.  “It is the best way to prevent the flu.”  She did not respond so I finished the history and examined the child.  She had no signs of a bacterial infection and was well hydrated.  I explained that it was most likely a virus and that I recommended checking for the flu.  She had been ill for less than 48 hours so treatment with antiviral medication was a possibility.

The test was positive for influenza A.

I wrote a prescription for tamiflu and explained that antivirals are different than antibiotics.  With antibiotics for an ear infection of strep pharyngitis, you expect to be feeling significantly better in 1 to 2 days.  The antivirals just helped make influenza a little less severe, a little shorter in duration.  “Also,” I told her, “Recent reports have indicated that this year’s strain of influenza A do not seem all that susceptible to tamiflu.  The medicine may only help a little bit.”

“Is she contagious?”  

“Well, yes,” I explained.  “The flu is very contagious.  I would keep her home from school until she has not had a fever for a full 24 hours.  Even then, she may still feel pretty crummy.  She will probably be out of school for the rest of the week.”

“Is it too late to get the flu shot?”

“I’m sorry?”  I was a little confused by the question.

“I have three other kids at home.  I don’t want them to get sick too.”