One set of travelers gets off the Kahului Airport tram at the Rental Car Center, while another rushes to board Tuesday afternoon. A study conducted at the airport in November suggests that more resident and visitor travelers may be bringing COVID-19 into the state than initially thought. The Maui News / MATTHEW THAYER photos

More resident and visitor travelers may be bringing COVID-19 into the state than initially thought, according to a Maui study released earlier this month.

The report, which has not been peer reviewed, said that seven out of 1,000 travelers who bypass quarantine via Hawaii’s Safe Travels program probably have COVID-19.

State officials had said that fewer than one out of 1,000 travelers using the pre-testing plan would likely bring the illness.

“Fix the Safe Travels a little bit so it’s a little more rigorous,” Maui District Health Officer Dr. Lorrin Pang, one of the researchers behind the study, said on Monday. “If people don’t believe it, just do a post-arrival study like we did. You either believe it or you don’t.”

Credited with the rollout of the state’s Safe Travels Program, Lt. Gov. Josh Green said Tuesday that the pre-travel testing plan is safe and that an “inconsequential number of cases” comes from travel to Hawaii.

Maui District Health Officer Dr. Lorrin Pang oversees a vaccination clinic at the University of Hawaii Maui College in December. Pang and other researchers conducted a study that suggests more travelers may be bringing COVID-19 into the state than initially thought.

The state’s Safe Travels program launched Oct. 15 to allow travelers with a negative nucleic acid amplification test result from a trusted partner to bypass quarantine. For more than six months, travel to Hawaii had been largely suppressed by Gov. David Ige’s mandate that travelers on arrival must undergo a two-week self-quarantine to curb spread.

With concerns over travelers who are incubating or people infected after pre-travel testing or during transit, Maui doctors Pang and Amy Hou led a rapid field study late last year. The state Department of Health Maui District Office, state Department of Transportation and Maui County Medical Society partnered to conduct the study and enrolled participants from Nov. 20 to Nov. 30 at five departure gates of Kahului Airport.

Published March 8, the study recommends that the Safe Travels Program implement another layer of protection beyond just a single pre-travel test.

Pang, Hou and other volunteers went to departure terminals of Maui’s main airport and randomly solicited hundreds of people to take a PCR test before leaving Maui. A PCR or polymerase chain reaction test usually involves collection of a sample via a swab and detects a current infection. Saying tests will help Hawaii’s travel program, they offered participants a free Hawaii face mask.

Of the 577 people screened by researchers, 184 were excluded because they did not meet the criteria that included having a primary residence outside of Hawaii, traveling from a location other than Hawaii, taking a test 72 hours prior to departure and planning a stay of 14 days or less.

Lt. Gov. Dr. Josh Green visits Maui Memorial Medical Center in January. Green emphasized that the state’s pre-travel testing plan is safe and that an “inconsequential number of cases” comes from travel to Hawaii.

Among consecutive eligible travelers, 282 consented and 111 declined to participate — a 72 percent participation rate.

The study said two were found to be positive with COVID-19 out of 281 tested, resulting in an estimated positivity rate of seven cases per 1,000 travelers.

“In an effort to assess Hawaii’s Safe Travels Program program, a study was initially conducted and reported a COVID-19 positivity rate of 0.65 cases per 1,000 travelers; however, it had less than 10 percent participation rate and its methodology had concerns for self-deselection and distortion bias,” the study said.

While not peer reviewed, the study has been reviewed by the Institutional Review Board of the Hawaii Department of Health, which approved that the study met the criteria for public health surveillance.

Hou, who spoke on the study during a Facebook Live talk last week, said one of the positives, a California traveler, entered Maui with a negative test taken three days prior to departure. The other, a visitor from Wisconsin, also bypassed quarantine with a negative test taken three days before departure.

“Hawaii was having 10,000 (travelers) to the state in a week period,” Hou said. “That works out to be in November to December about 50 to 70 potential travelers coming in per day that were infected.”

She added that 17 to 30 potentially infected travelers were likely coming to Maui per day during that time frame. Maui’s projected capacity is 10 infections per day, according to the Department of Health.

“That’s really disturbing,” Hou said. “That’s more than we’re hoping to handle especially with the variants being potentially more infectious.”

Travelers with COVID-19 are not always recorded with the DOH as a travel-related case, Pang said during the Facebook Live talk, because most won’t know they have COVID-19 unless they become severely ill after arrival and seek medical attention.

“But you know it’s there,” Pang said. “The thing that really reinforces it is because of the variant. The travelers brought in the Californian variant. We could see it rise in Maui over the last 10 weeks when it first came.”

Due to variant strains coming into the islands, Hawaii is at a pivotal point, said Hou, who added that she feels strongly about a “post-arrival test.”

“I feel like we’re in a really critical point where we can reduce and limit the amounts of other strains coming in,” she said.

Pang said Monday that there are ways to add layers of protection, such as a mandatory second rapid test on arrival. He added that a vaccination passport can also be explored.

Leading up to the Safe Travel Program’s launch, Green said last year that fewer than one per 1,000 travelers would likely bring COVID-19 to Hawaii through the program.

He maintained the safety of the program on Tuesday.

“Two million travelers (residents, visitors and business travelers) have safely come to Hawaii and we’ve had an inconsequential number of cases coming from travel as the data collected by the Department of Health shows,” Green said via email. “What we learn from studies done by UH Epidemiologists, Department of Health Maui staff and the most recent the Lancet Study, give policy makers the information they need to create protocols that are safe and practical to execute with the resources available.”

The Lancet study said that a PCR test taken within a three-day window of traveling should screen out 88 percent of positive travelers.

Statewide, Hawaii has seen 1,883 cases so far in March, according to DOH data. Of the 1,458 cases in which the risk factor was known, 88 percent were associated with community spread, 8 percent were associated with resident travel and 4 percent with visitor travel. Maui County has recorded 608 cases so far in March. Of the 500 cases in which the risk factor was known, 96 percent were associated with community spread, 3 percent with resident travel and 1 percent with visitor travel.

Green added that the Safe Travels program will evolve and eventually allow for fully vaccinated passengers to travel without taking a pre-arrival test.

“This concept is being described as a ‘vaccine passport’ and it’s being contemplated nationally and globally,” he said. “Vaccine passports are not a new concept, they have been used in the past for other infectious diseases such as Yellow Fever.”

To view the Lancet study, visit www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00134-1/fulltext.

To view the study conducted at the Kahului Airport, visit www.medrxiv.org/content/10.1101/2021.03.06.21251482v1.

* Kehaulani Cerizo can be reached at kcerizo@mauinews.com.