State health officials are warning the public of a COVID-19 cluster stemming from a youth football tournament held on the mainland. Thus far, 13 Oahu and Maui residents who returned home this week were sickened and tested positive.

The Department of Health urges anyone who attended the Pylon Mecca 7v7 tournament in Utah and Nevada to take a COVID-19 test and to quarantine for at least 10 days and monitor themselves for four days thereafter, including players, parents and spectators.

While the Pylon Mecca 7v7 tournament was played in Utah and Nevada, Hawaii health officials said symptoms in 13 Hawaii residents began roughly within 48 hours after exposure at the games in Mesquite, Nev., last weekend.

The Health Department shares details of clusters only when there is an imminent health threat to the public, and experts think there is a rapidly developing threat, said DOH spokesman Brooks Baehr. “We want to squash this as quickly as we can.”

Meanwhile, on Kauai there has been a steep rise in the number of COVID-19 cases, with 55 active cases reported Friday.

Although COVID-19 vaccinations are open to those age 16 and older, the Centers for Disease Control and Prevention has still not approved any vaccine for children 15 and younger.

Kauai Mayor Derek Kawakami reported that the island, which had enjoyed the lowest rates in the state, had 16 new cases Friday, including four children and 12 adults. Of those, 14 were community-acquired.

“We know that as an island we have let our guard down a little, being that we were so safe for so long,” Kawakami said. “Based on Department of Health data, our mask compliance is the lowest in the state.

“Wearing a mask helps to prevent you from unknowingly spreading the virus to others, especially our children and those that cannot get vaccinated.”

Most of the cases involved Kauai residents who traveled interisland, and most were unvaccinated.

State health officials said Friday that the youth football tournament cluster involved seven Maui residents and six Oahu residents so far, but officials expect more cases.

The ages were not disclosed at a news conference held Friday via Zoom.

“We’re trying to be proactive in this situation … before it became larger,” DOH lead contact tracer Telle Matagi said. “We wanted to make sure that everyone knows that we’re not pointing fingers. We’re not blaming anyone, but instead what we’re looking to do is support them and make sure we minimize exposure and we contain it.”

She urged people to answer calls from contact tracers, who can help find a place to safely quarantine, outside the home, if necessary, so that the virus is not spread to family members and communities.

The cluster involves two community league teams with players ranging from high schoolers down to children 14 and below, and not from any particular school or area.

The mainland-based tournament was played April 24-25.

Those in attendance began returning home Sunday night and Monday at Honolulu and Kahului airports, and others were still en route to Hawaii, Matagi said Friday.

The first cases developed Wednesday and Thursday. Those sickened experienced chills and fever, Matagi said.

As participants in the Safe Travels program, testing for the coronavirus had to be done three days prior to their return travel, so most of the testing was done prior to the April 24 commencement of the games.

Matagi said they do not yet have any information on whether mainland participants in the tournament have contracted COVID-19. She said many of the Hawaii participants have family members who live on the mainland.

“It looks like the source, at least from our very beginning of our investigation, appears to be the tournament because that seems to be the event that everyone was a part of, and then within 48 hours became symptomatic or tested positive,” she said.

Those who displayed symptoms after their return home went to their doctors and were advised to be tested.

The Health Department advises any who attended the tournament or were in close contact with anyone who has tested positive to monitor themselves for symptoms such as fever, chills, cough, shortness of breath, fatigue, loss of smell or taste, head and body aches, sore throat or congestion.

They also should isolate themselves in a separate room and stay away from others, and wear a mask if it is necessary to be around others. Have a separate bathroom, but if that is not possible, clean thoroughly after use. Also, use separate plates and cutlery.

Matagi said she believes scholarship opportunities was one of the reasons the families took the risk of attending the tournament during the pandemic.

“Every family has to make whatever decision they make is what’s best for their family,” she said. “We don’t judge them. Whatever happens, we’re there to support them.”

Matagi urged that even if people are outside, if they are closer than 6 feet, they should still wear a mask.

According to DOH, Kauai’s seven-day positiv­ity rate was 2.5%, up 38% from the previous day, compared with the statewide 1.5% rate. The Health Department reported 118 cases new cases Friday statewide.