The family trip to Hawaii was full of precautions: Both parents had been fully vaccinated and tested negative for the coronavirus before leaving, as the state requires of visitors who want to avoid a long quarantine.

But still, the couple’s young son developed symptoms of covid-19 shortly after arriving in Hawaii from another state. The child, who had underlying health conditions, was taken to a hospital and later died.

The department did not provide the boy’s exact age. He was younger than 11, according to a news release.

“Possible sources of exposure are still under investigation,” Brooks Baehr, a spokesman for the Hawaii Department of Health, said in an email. “Symptoms developed within hours after arrival in Hawaii, so it is unlikely the child was exposed here.”

It was the state’s first pediatric covid-19 death, the Health Department said late Tuesday. The state has reported 479 deaths in which covid-19 was a contributing factor.

In the United States, there have been about 3.7 million cases of coronavirus in children and at least 296 deaths as of earlier this month, according to the American Academy of Pediatrics. That is compared to nearly 32 million total cases and almost 570,000 deaths, according to data from the Centers for Disease Control and Prevention.

The date of the child’s death was not available, but Baehr said it was recent. His home state was not released, nor was any other information about the trip.

Hawaii has strict entry requirements for tourists age 5 and older: either self-quarantine for 10 days upon arrival or take a coronavirus test from an approved partner within 72 hours of departure. In this case, while the child’s parents tested negative, he did not undergo testing before traveling.

“This was an unusual and unfortunate situation,” Baehr said. “Broader vaccination coverage in the general population increases protection of susceptible individuals who have not yet had the opportunity to be vaccinated, such as young children. This is another good reason to get the shot when it is your turn; this helps protect others in the community.”

Hawaii reopened to tourism in October and has had a steady increase in visitors, even with its testing requirement. The state announced recently that it will start to ease restrictions for vaccinated travelers, beginning with residents who were vaccinated in Hawaii. They will be allowed to bypass testing rules when traveling between islands starting May 11.

The exception is expected to follow for tourists from the continental United States later in the summer. In a news conference about the decision earlier this month, Gov. David Ige (D) said the move was possible because of the state’s collective action in helping to keep infections and mortality rates low.

“While we mourn all victims of covid-19, today’s announcement of the death of a child from this virus is especially heartbreaking,” Ige said in a statement Tuesday, offering condolences to the boy’s family. “The state and counties will continue to make responsible decisions on COVID restrictions based on science, with the goal of protecting the health and safety of the people of Hawaii.”