Parents who do not vaccinate their children have expressed worries about side effects, concerns over cost, moral or religious objections, and fears that vaccines lead to autism — an idea that has been widely debunked.

But health experts say a resistance or refusal to vaccinate can raise the chances of an outbreak by putting at risk people who cannot be immunized for medical reasons. The World Health Organization identified “vaccine hesitancy” as one of this year’s 10 notable threats to global health.

Tetanus, a life-threatening disease that is transmitted through open wounds and causes painful muscle spasms, declined drastically in the United States after the introduction of a vaccine in the 1940s. A series of shots are recommended in infancy and childhood, as well as at certain other times throughout life.

Today, the disease occurs “almost exclusively” in people who have not been vaccinated or who have been undervaccinated, another article in the Morbidity and Mortality Weekly Report said last year.

In Oregon, the boy, who was not identified, had not received any immunizations, Dr. Guzman-Cottrill said.

When he arrived at the hospital, he was alert and asked for water, but could not open his mouth. Doctors gave him medicine, including an initial vaccine for tetanus, known as DTaP, according to the article. But his condition was perilous. He spent more than a month on a ventilator, the article said.

He also stayed in a darkened room for weeks, where he wore earplugs and was exposed to little stimulation to avoid making his spasms worse, Dr. Guzman-Cottrill said. His pain was so bad, she said, that doctors took care not to trigger him even with their voices. “We had to whisper,” she said.