Kids’ Vaccine Safety, by the Numbers
Adverse events from COVID shots are mild and rare
A note: This is about vaccines for 5- to 11-year-olds. Last week, Pfizer announced that those for younger than 5 would be delayed. The company is not seeing a sufficient response to the dose being given to kids 2 to 5 and is going to move to three doses. This will take more time. I know there are some parents who are devastated by this delay, and I hear you. But I also want to reassure you that children in this age range are at extremely low risk for serious illness, substantially lower than with your own vaccine. I know I’ve said that before, and I know it is not enough, but it is still important to remember.
When COVID vaccines for 5- to 11-year-olds were first approved, it was clear to me that there were three groups of parents. Group 1: people who would kick down the door to be first in line for vaccination. Group 3: people who are not going to vaccinate their children unless it becomes required. And then there is Group 2, somewhere in the middle. Parents who aren’t necessarily opposed to vaccinating in this age group but who wanted to wait, to see the first round of vaccines, to make sure the relatively small initial trials hadn’t missed rare adverse events.
For this “waiting” group, I would suspect the decision about vaccination is starting to feel more urgent. Omicron is more contagious, even if not more serious, and vaccination provides protection for children against COVID infection. This protection means they are less likely to spread the virus to vulnerable relatives. Also, we’re starting to see more restrictions pop up in some states — kids may be restricted from recreation or school as a result of not being vaccinated. All the reasons to vaccinate your kids before (which I talked about here) are now more true.
The good news, then, is that we are now in a much better position to start talking about large-scale safety results. The American Academy of Pediatrics reports that approximately 5 million children ages 5 to 11 have received at least one dose of the COVID-19 vaccine. A subset of these children have had two doses. These sample sizes are getting large enough that even very rare events should start to show up. If there is a complication that arises 1 in a million times, we’d already expect to see at least five of them. And that’s a really, really rare complication.
Public-health officials have emphasized that we aren’t seeing concerning reports of side effects in kids. Which is a great message (and I think a correct one), but as usual it lacks detail. For at least some worried parents, they want to see the actual data behind this statement. What I want to do today, then, is dig into the data that is coming in through the Vaccine Adverse Event Reporting System, or VAERS, about the COVID-19 vaccine in kids.
What is the VAERS?
Before getting started, let’s review what the VAERS is. It is a CDC reporting system for adverse events associated with vaccinations. The CDC collates reports from individuals (including medical providers, but also patients and caregivers) about incidents possibly linked to vaccines. The agency does this for all vaccines, not just COVID, and you can access the data publicly here.
The VAERS is a valuable data set, since it gives a window into possible issues with vaccines, and it harnesses the power of distributed information to get that information quickly. However, it is often difficult to draw strong causal conclusions from what we observe in the VAERS.
To understand why, consider the following: Imagine that people believed that cutting an infant’s fingernails led to possible illness, and thus there was an adverse-event reporting system for fingernail cutting.
In all likelihood, this system would get all kinds of reports. There would be parents saying that the day after they cut their infant’s fingernails, the baby came down with a terrible fever. Others would say they had a very liquid-looking poop. You’d get reports of children who didn’t sleep well for days after the fingernail cutting, and others about babies crying uncontrollably for hours.
These would all be true things that happened. But they would not be causally linked to the fingernail cutting! Babies have weird poops and they cry a lot. In order to figure out whether there was any real link, you’d need to know the general base rate of these events — how likely people are to report them when there was no fingernail cutting. But that isn’t something we have a reporting system for. There is no website where you can report every time your kid has an unusual poop.
You’d have to try to piece together whether these adverse events really seem more common among babies whose nails are cut than those whose aren’t. This is especially hard for things that happen all the time, like “baby cried.”
In your fingernail-reporting system, you probably would also learn something. You’d get many reports of finger injury — cuts in need of Band-Aids. This is not something that happens all the time, and there is an obvious mechanism for the connection with nail cutting. So you would probably conclude that fingernail cutting is linked to accidental finger cutting, which is true.
This example extends to vaccines. If you tell people to report anything unusual that happens after a vaccine, they will share a lot of incidents. The challenge — which I will try to meet below — is to figure out what to make of them. To try to pull out the signal from the noise.
With that background, let’s dive into the data.
Overview of data
To do this analysis, I downloaded all the VAERS data for 2021. The first file has a full list of incident reports, including the text in the report (there’s a free-entry field), information on hospitalization, and characteristics of the individual like their age and sex. The second file lets you link in vaccine type, and the third has extracted some information on the main concerns so you do not have to parse the text yourself.
I merged these together and limited them to ages 5 to 11 and the COVID-19 vaccine.
When I did this, I found a total sample of 3,198 adverse events. As noted above, about 5 million children have received a first dose of the COVID-19 vaccine. If (say) a third of these children have also received a second shot, that is 6.65 million doses. This adverse-event rate would be, then, about 1 in 2,100.
But what are these events? We can see details!
Of the 3,198 adverse events, 915 are kids (nearly all of them age 11) getting the COVID-19 vaccine before they were eligible. The reason for this is that their parents lied about their age. To give you a flavor, here are a couple of examples in the text…
Patient was booked by his family in system as his 13 year old sister. Information was changed at vaccine site to this patient who was only 11 years 5 months old. This was not caught until after the patient received his shot. We are not aware of any untoward effects. Patient’s mother was informed this would be reported to the DPH and CDC. Patient’s mother indicated she was aware he was not eligible at this time. This was her second attempt to get him vaccinated as he was turned away at a previous clinic.
Father took her to a pharmacy and lied to the pharmacist about her birthday so she could get a COVID vaccine so he could go on vacation. Parents are divorced and mom has sole custody and father is not allowed to make medical decisions without her consent. He also lied to the pharmacist again when they were confirming the birthday and falsified medical documents to make it appear that the patient was eligible for the Pfizer covid vaccine.
These incidents do not have negative vaccine impacts associated with them. The adverse event is the incorrect vaccine.
Removing these, we are down to 2,283 adverse events.
Dosing issues, etc.
Of these remaining 2,283 reports, 295 of the records specifically indicate that there was no adverse event; these are generally issues with incorrect entry of the vaccine record, or some issue with preparation. Another 539 of them are cases of incorrect dosing (child given adult dose; child moves arm so full dose not delivered) or an issue with vaccine preparation. In these 539 cases, there were no additional side effects reported. The event, again, is the dosing.
Removing these, we are down to 1,469 adverse events, or an adverse event rate of about 1 in 4,500.
Most common side effects
Digging into these 1,469 cases, we can start to isolate the most common complaints. The three most common categories are nausea and vomiting (present in 18% of cases), fainting or dizziness (25% of cases; mostly dizziness), and pain (present in 12% of cases, typically at the injection site). These are minor and self-limiting side effects in nearly all cases.
This side-effect profile is consistent with what we see, for example, with the flu vaccine. During the 2019 flu season, looking at adverse-event reports for kids getting the flu vaccine, we see pain (17%), fainting and dizziness (16%), and nausea (7%) among the leading issues. For the flu vaccine, we also commonly see rash and swelling, which doesn’t show up as prominently in the COVID vaccine.
Put simply: Of the 5 million kids who were vaccinated for COVID, there are 1,469 case reports, of which 25% include a symptom of nausea or dizziness. This is a very, very small share of the overall 5 million.
There are other isolated symptoms listed in these reports. Anxiety. Neck pain. Mouth swelling. Malaise. Eye pain. Lip blister. Some of these could be vaccine-related; others are unlikely to be. This is also true if you look at symptom lists after the flu vaccine.
Putting this together, it seems that the overall profile of most of the commonly cited side effects is similar for the COVID vaccine and the flu vaccine, which is a natural comparison.
Nearly all of the adverse events reported after the COVID vaccine are mild and self-limiting. This is great. However: it is worth looking at whether there are any serious events.
There are 42 cases in which an adverse event is associated with a hospitalization. In a number of cases, the hospitalization does not seem to be a result of the vaccine. There are five cases of appendicitis. There are four cases of hospitalization with COVID-19 infection. There is one psychiatric hospitalization for depressive thoughts.
In other cases, it’s harder to tell. And if you read about those, they can seem really scary. This is a feature of these reports that is also true for the flu and other vaccines. Sometimes kids get sick and it’s scary. But in many cases, it seems to be clearly unrelated to the vaccine. There isn’t anything in these 42 or so cases that would suggest any particular vaccine-related concerns. It is likely that all of these, or nearly all, are incidental. Remember: this is on a base of perhaps 5 million children, 6.5 million vaccines. It’s really, really small.
What about myocarditis, the heart inflammation that has been cited as a side effect of the COVID-19 vaccine in male teenagers and young adults? The VAERS system does show a substantial number of reports of myocarditis in this older age group. It’s part of how we know there are risks there, and it’s a good illustration of the value of such data.
For the younger age group, we do not see anything like this. In the hospitalizations, there are two cases in which myocarditis was suspected, both in 10-year-old boys, both recovered.
Again, this is in the context of millions and millions of shots. Even if both of these were confirmed myocarditis cases, we’d be looking at a risk of perhaps 1 in 1.5 million for boys. There are many activities you do each day that carry more than a 1-in-1.5-million risk of a daylong hospitalization.
These safety data are extremely reassuring. If you’re waiting to see good evidence on the real-world safety of these vaccines, this is it.
I know some parents worry about the long term. The fact is, there isn’t any data that will tell you about vaccine side effects in 10 years. Having said that, there is absolutely no reason to think such side effects would crop up. In vaccines, side effects tend to be fast. You could make a similar case that we do not know about the potential long-term side effects of COVID itself.
Kids remain at low risk of serious illness from COVID. The benefits of vaccination are lower case rates, less risk of spread, and, at least in some locations, more freedom from restrictions. These are real benefits, and these data now show they can be achieved safely.