An 8-month-old receives a vaccination in Dallas on March 8, 2019. (Vernon Bryant/The Dallas Morning News/AP)

A TETANUS vaccine shot costs about $30 a dose. Five doses are enough to prevent a child from contracting the disease, which means immunization runs whoever is paying for care $150.

A 6-year-old unvaccinated boy diagnosed with the neuromuscular disease in Oregon spent 47 days in an intensive care unit and 10 more in a pediatric hospital before he was transferred to a rehabilitation center. His medical charges in the hospital were $811,929. That’s nearly 5,413 times the cost of vaccination — plus more than a month of misery for a very sick child. When physicians told the family their son should receive a follow-up dose of the tetanus vaccination, they refused.

Study after study has disproved the common fear that keeping up with your shots can lead to autism. Still, ignorance and misinformation are dragging vaccination rates down. Several measles outbreaks have already occurred in the United States this year, prompting necessary calls for legislative change. Only three states require vaccinations for children to attend kindergarten without any nonmedical exceptions. Nearly 20 allow personal objections that are not religious.

The argument that states should permit only narrowly defined religious objections to vaccination hinges on the idea of herd immunity, which prevents contagious diseases from spreading if a high enough proportion of a community is vaccinated. This is why vaccination requirements are linked to a child’s ability to attend school. Parents’ right to choose what happens to their own children is outweighed by the state’s interest in protecting all children.

Tetanus, while not itself infectious, is included in vaccination requirements because the shot immunizing against it also protects recipients from whooping cough and diphtheria. But the Oregon case is a reminder that the vaccination controversy is not only about whether parents have a right to endanger other people’s children. It is also about whether they have a right to endanger their own. The six-figure cost in Oregon is startling enough. The cost to the 6-year-old boy, who could barely walk when he was transferred out of the ICU, is tremendous.

Child-endangerment law already recognizes that parental control over children’s lives is not absolute, even when it comes to medical decisions. Judges, for instance, have ordered that children with cancer receive chemotherapy despite their families’ objections. Parents have substantial leeway to weigh risk as they see fit — but when does a parent’s right to be irresponsible run up against a child’s right not to contract a life-threatening illness? As states consider taking steps to combat anti-vaccination fervor, and as the federal government considers intervening where they fall short, herd immunity can’t be the only consideration.