by Raywat Deonandan, PhD
Epidemiologist & Associate Professor
University of Ottawa
(I add my credentials to these COVID-19 blog posts in case they get shared. I want readers to know that my opinion is supposedly an educated and informed one)
Someone recently asked me to comment on COVID vaccination and children, specifically to offer guidance on whether they should get their child vaccinated.
Here’s the thing: I’m not comfortable telling parents whether or not to vaccinate their children against this disease. This is ultimately a personal choice, and is qualitatively different from the well established pediatric vaccines, like those for polio, rubella, diptheria, rotovirus, and measles, all of which I will heartily encourage your child to receive.
Instead, I will offer an approach for how to navigate this decision for yourself.
As always, I offer this disclaimer: I am a PhD scientist, not a medical doctor. So I cannot and will not offer clinical advice. As well, I own shares in all of the companies that manufacture COVID-19 vaccines for Canada. (Worth hundreds! Hundreds of dollars!) And I have done paid consulting work for many drug companies, most recently for AstraZeneca for whom I served on a medical advisory panel to react to their vaccine efficacy and safety data. If this disclosure compels you to discount my opinion on these matters, that is certainly your right.
Ultimately, this is about balancing risk vs reward. Specifically, how do we weigh the risk posed by the vaccine vs the reward offered by vaccination?
So let’s break it down like that.
1. Risks Posed by the Vaccine
Presently, the only COVID-19 vaccine authorized in Canada for use in children is that made by Pfizer.
Their recent trial enrolled 2,260 American kids aged 12-15. A total of 18 COVID cases were observed in the trial, all of which were in the placebo group of 1,129 people. None of the 1,131 people who got the vaccine contracted the disease.
This means that, according to these data, the vaccine has 100% efficacy on adolescents. Follow-up showed strong immunity a month after the second dose.
100% efficacy! That’s astounding. But do remember that it was found to be 95% efficacious among adults, so this isn’t too surprising. And real life effectiveness will always be a little less than trial-computed efficacy. So this number will come down as millions of kids are vaccinated.
(Pfizer and other companies are presently pursuing studies on children as young as 6 months. But no data are yet available for that cohort.)
While the full data have not yet been published, no serious safety signals have yet been indicated. Do remember, though, that there were only two thousand or so children in this trial. As millions become vaccinated, rarer effects will be observed. This is to be expected, but of course is not necessarily comforting.
But we can look at how the vaccine has been experienced by adults to get a good sense of how children will react. And tens of millions –possibly hundreds of millions– of adults have taken the Pfizer jab.
So what do we know about the safety of the vaccine among adults? Let’s look at Ontario data. Out of almost 5 million doses of the Pfizer vaccine given as of May 15, 2021, there were 57 “serious” adverse reaction reports. That works out to about 0.001% of injections resulting in a serious event.
What’s a serious event? One that “results in death, is life-threatening, requires in-patient hospitalization or prolongs an existing hospitalization, results in persistent or significant disability/incapacity, or in a congenital anomaly/birth defect”, according to the WHO standard definition.
In the Ontario adverse reaction data, three of the 57 were deaths. Yikes. That’s not good, right?
But hold on: “One report of death occurred in a resident of a health-care institution with significant co-morbidities. The cause of death was not attributed to the vaccine. The second report of death occurred in a community dwelling senior with complex cardiovascular and renal conditions, wherein the [adverse event] may have contributed to but was not the underlying cause of death. The third report of death occurred in a community dwelling senior with multiple comorbidities including heart disease and an autoimmune disorder. The cause of death was not attributed to the vaccine.”
In other words, none of the three deaths were caused by the vaccine. And even if they were, it would work out to a risk of death of 0.00006%.
2. Rewards Offered by the Vaccine
Now this is a little trickier to compute. We all know by now that children who contract COVID-19 are far less likely than adults to develop symptoms, to be hospitalized, and to die. The risk of the disease to them is very small… but not zero.
Though the infection fatality rate for young people is very small, we still expect that for every million 12-15 year old who contracts this disease, 20-30 will die from it.
This works out to a risk of death if you get COVID of 0.003%, which while vanishingly small, is still at least 50 times greater than the risk of dying from the vaccine.
But there are two remaining issues. First, this isn’t just about death, but also about illness. And second, the risk of death or illness from COVID must be multiplied by the probability of actually getting COVID in the first place.
In the USA alone, there have been thousands –nay, tens of thousands— of children hospitalized for COVID. We should not become overly comfortable with our children becoming infected with this virus.
As Gideon-MK puts it, “So the acute to children risks are relatively low. They are a bit higher than the risks from regular seasonal influenza, a bit lower than the risk of some of the nastier childhood diseases like measles, but they are much lower than the risks that adults face from coronavirus infections.”
It’s that second part that confounds me: what is the risk of your child contracting COVID in the first place? This is the most important metric in my mind, and I don’t have a good answer for you. It comes down to the incidence rate. Is it low enough?
We all agree that the best way to keep children safe from this disease, especially in schools, is to keep it out of the community in the first place.
If the incidence rate is high, then the probability of your child encountered an infected person is high, therefore their probability of becoming infected is high. As that probability approaches 100%, the more the risk of death approaches the IFR of 0.003%. But if the incidence is low, then the probability of getting the disease is also low, and the risk of death approaches zero.
So the risk of death –and of illness– hinges on how much disease is currently in the community. As adults become vaccinated, and as our strong mitigation efforts bear fruit, it seems highly likely that the incidence rate will drop fast in most parts of Canada.
3. What About Herd Immunity?
Well now we’re into another realm. The risk of the vaccine harming your child is really really small. But the risk of your child being harmed by COVID if the incidence rate is low is also really really small. So what’s the tie breaker?
Some will argue that the tie breaker is that vaccinated children contribute to herd immunity.
If we assume that herd immunity for COVID-19 kicks in at the point at which 75% of the population has immunity, and that our vaccines are 95% effective, then 80% of the Canadian population must be fully vaccinated for this magical threshold to be reached.
Guess what the percentage is of Canadians who are adults? Yep, about 80%. This means that 100% of adults would have to accept vaccination before we can have the herd immunity conversation. And as we all know, there is sufficient vaccine hesitancy an skepticism that getting 100% acceptance is nigh impossible.
So if children were also vaccinated, our chances of achieving that magical goal go up substantially.
Really, this to me is the most compelling reason for pursuing vaccination among children. It’s not necessarily to protect the children, who have a very small overall COVID risk, but rather to protect other people. Those other people might be an unnamed greater population who benefit from herd immunity, or it might be the relatives of these children who have a higher risk profile than the children themselves. Though it is assumed that these relatives would themselves be vaccinated.
The ethical pushback against this mindset is that we have no other precedent that I can think of wherein we ask children to accept a risk —albeit a vanishingly tiny risk– to protect others from a disease that poses a similarly vanishingly small risk to the children themselves.
There is another ethical issue having to do with why low risk children are eligible for vaccination at all when there are still unvaccinated seniors among us in parts of the world where the disease is raging, and while there are seniors still awaiting their second doses in places like Ontario.
But for the parent, this comes down to a decision based on individual risk vs individual reward. As noted, I am reticent to offer explicit advice on this matter. I just hope my thoughts here have been useful in helping to understand the issues. For a deeper dive into this question, I recommend Gideon M-K’s full post on the issue, “Vaccinating Children Against Covid-19: Should we be protecting kids from coronavirus infections?“