Post #1317: COVID-19 Vaccine side effects in children ages 5-11

Posted on November 9, 2021


I saw an article yesterday listing out all of the extremely likely side-effects you should expect if you get the COVID-19 vaccine for your 5-to-11-year-old child.  It made it look like a terrible gamble.  If I’d seen that article, and nothing else, I’m not sure I’d have gotten my kid vaccinated.

The only problem is, they showed the numbers for vaccinated children ages 5-11 in complete isolation.  They didn’t show how young children fared, relative to teens.  And they didn’t compare to the placebo group.  Or to typical self-reported side-effect rates for (e.g.) flu vaccine.

If your job had been to scare parents away from vaccinating their kids, you could not have done a better job of it than by cherry-picking that exact bit of information.  And showing zero context.

Just to be clear about how these numbers arise, if somebody had asked me if I’d felt fatigue or muscle pain in the past week, the answer would have been “yes”.  As it would, pretty much any week of the year.  If I’d been part of the study, by responding honestly to that question, I’d have been contributing to the reported potential side-effect rate of the vaccine, as shown in the popular press.

This isn’t to dismiss the side effects.  They sometimes occur.  It’s more that you need some context to make sense of the reported side-effect rates.

I thought I’d get the actual data, and show how the side-effect rates for children look in proper context. 

Here’s the original slide of results, as presented to the U.S. CDC, which I will now simplify to highlight the main findings:

Source:  Presentation to CDC, “BNT162b2 (COVID-19 Vaccine, mRNA) Vaccine in Individuals 5 to <12 Years of Age”, November 2nd 2021, Alejandra Gurtman, MD, Vice President. Vaccine Clinical Research and Development, Pfizer Inc

Point 1: The side effects … were generally milder and less frequent in 5- to 11- year olds than they were in adolescentsPutting aside that most of the side effects disappear within one to three days, little kids actually had lower rates of side effects than teens and adults.  That’s what these pairs of bars below are showing.  So if you weren’t too worried about vaccinating your  sixteen-year-old, you should be even less worried about vaccinating your six-year-old.


Point 2:  Side effect rates were only modestly higher for children actually getting the vaccine, compared to placebo.   These contrasts below are between vaccine and control groups.  If I had to condense it, it would say that compared to children who got the placebo, the vaccinated children were:

  • 10% more likely to report fatigue or headache
  • 5% more likely to report fever or chills
  • 3% more likely to report muscle or joint pain.

Point 3:  And again, to be clear “If they arise, side effects generally are gone within one to three days.”

There’s another potential point of comparison, which is the rate of the same reported side effects for standard flu vaccine.  One might reasonably ask how frequently these same side-effects get reported for flu shots.  That’s a vaccine that most of use get annually without a thought in the world of having a significant adverse reaction.  (N.B., a flu shot is recommended in the U.S. for everyone over the age of six months, so it’s a vaccine that is definitely recommended for this 6-11 age group.)

It’s tough to get any hard numbers on that, probably because the flu vaccine has been considered safe for so long.  Here are a few bits and pieces.

Of the side effects tracked above for COVID-19 vaccine, the one article I found listed these rates of side-effects in adults, for flu vaccine:

  • fever (perceived) 15.2%.
  • fatigue (17%)
  • muscle pain (17.7%)

Here are the side effect rates for Fluzone in adults:

  • Muscle pain 18.9%
  • Headache 13.1%
  • Shivering 4.8%
  • Fever 0.9%

I’m not going to beat this point to death, because my point is simple.

Side effects are not some new thing that just happened with the COVID-19 vaccine for young children.  The common side-effects of the COVID-19 vaccine in children are the same as the common side effects, for the same vaccine, in teens and adults.  And the same as the common side effects of the flu vaccine. 

The rate of side-effects from the COVID-19 vaccine, in young children, is less than in teens and young adults.  And, very roughly speaking, the rate of side effects of COVID-19 vaccination in children is not grossly different from the rate of the same reported side effects from flu vaccination in adults.

If you didn’t hesitate to get your teenage kids vaccinated, there’s no new reason to hesitate about younger children.  And if you get the flu vaccine every year for you and yours, you have arguably taken on as much risk of adverse events with that as you will with the COVID-19 vaccine.

It is all-but-impossible to get those conclusions out of standard mainstream news reporting about this.  It’s just too dog-bites-man, I guess.  It doesn’t fit into the modern style of fear-oriented journalism.  Instead, what will catch your eye is some chart showing an apparently high rate of side effects.  With no way for you to know that this is completely normal, no different from the experience of other age groups, and not hugely different from the side-effect rates for flu vaccine.