We knew this moment would come eventually: Pfizer/BioNTech has applied to the Food and Drug Administration for authorization of its vaccine in children 5 to 11 years old. The good news is that many kids will soon be protected against covid-19, along with their families and communities. The bad news is that we’re eventually in for a hell of a fight over whether to mandate those vaccines as a condition of school attendance.

Yes, we should. But that answer would be hotly contested even if there weren’t good arguments for the other side. And the other side does have some strong arguments, which proponents of a mandate will have to contend with if they are going to prevail.

The argument for the coronavirus vaccine is obvious: It protects kids against a small but real risk of complications from contracting the virus. Nearly 30,000 children were hospitalized for covid-19 in August, and complications can include myocarditis or even death, so this is a big deal. Vaccines also help protect the families and communities that kids would otherwise infect, because groups of children, with their naive immune systems and uneven personal hygiene, make ideal reservoirs for highly contagious diseases such as covid-19.

There is a reason that mumps, measles and whooping cough were known as “childhood diseases” before vaccines were available for them, and it’s not that those pathogens have special affinity for kids. Children were just so darn efficient at spreading such illnesses among themselves that almost everyone caught them before they reached the age of 18.

Today, we reach “herd immunity” against those diseases with childhood vaccines so that even the small percentage of people whose vaccinations haven’t produced immunity, or the larger percentage whose immunity wanes over the years, remain protected. Many will undoubtedly ask why we should vaccinate kids who are at low risk to protect higher-risk adults. The answer is that this has always been a consideration with childhood vaccination, as many childhood diseases are much more serious in adults than they are in children. My grandfather, who caught mumps as an adult, suffered severely for weeks; his children got off with mild cases.

Childhood vaccination would be a powerful weapon to add to our arsenal against covid-19 as well. And to acquire that weapon, we will need a mandate, as we learned in the fight against measles, mumps and whooping cough. Vaccines that aren’t mandated stall out well below the population coverage needed to produce herd immunity.

But as with any weapon, there are some dangers, and we can be sure that opponents of mandates will point them out, loudly and often.

The main danger is the physical side effects of the vaccines. There seems to be a link between the vaccines and an increased — though still low — risk of myocarditis, especially in teenage boys. This is not entirely surprising, since myocarditis is a serious risk of the disease itself, even in children. But many parents understandably worry — and worry, too, about possible longer-term side effects we haven’t yet identified. What if some terrible complication takes 40 years to develop?

That’s unlikely, since vaccine side effects tend to show up pretty quickly. The bigger problem with that argument is that it’s just as true of covid-19. Right now, we know some children do suffer complications that require hospitalization. We can’t completely eliminate the possibility that longer-term complications may materialize later.

That leaves the undoubted infringement on personal liberty and parental rights that comes with a mandate. That’s obviously an infringement our society has already decided is acceptable in principle, but in practice, in this particular instance, it still has to be justified.

I think the data does justify it, amply: Even among children, covid-19 is not wildly less deadly than other diseases we do mandate vaccines for, such as chickenpox or mumps.

Of course, a lot of parents are clearly going to disagree. And that adds another risk: that if vaccines are required for their kids to attend school, some parents may decide to pull their kids out rather than comply.

That’s not a problem if all those parents are conscientious home-schoolers who will make sure their kids are healthy and well-educated. But not all of them will be. We have seen devastating learning loss during the era of remote schooling. Some school systems have lost track of a bunch of vulnerable kids entirely. That is a real issue that we need to contend with, and address, if we go ahead with mandates.

Then again, so is an ongoing pandemic. And more lives lost. And more kids losing parents. And forcing kids to spend their school day masked, lest a stray virus escape.

The virus has left us with no good choices, only better or worse ones. Mandatory vaccination may not be a great option. It is nonetheless the best one we have.