Hawaii health officials remind the public to remain vigilant and continue wearing face masks as required even as restrictions on Oahu are eased and the state’s average number of daily coronavirus cases continues to trend downward.

A Centers for Disease Control and Prevention study published Wednesday offers lessons learned from an Oahu cluster last summer traced to three fitness centers.

The investigation for the study, led by the Hawaii Department of Health’s acting state epidemiologist, Dr. Sarah Kemble, found that SARS-CoV-2 is highly transmissible in certain settings such as indoor fitness facilities, and reinforces how important it is for their staff and patrons to wear face masks, particularly during high-intensity activities.

At the time, face masks were not required — but are now — at fitness facilities.

The study’s findings come as Oahu moves to Tier 3 in its reopening framework today, which allows gyms and fitness facilities to operate at 50% capacity, up from 25% under Tier 2. Also, indoor group fitness classes can now include up to 10 participants, up from five under Tier 2.

On Wednesday, the state Health Department reported four new coronavirus-related deaths and 50 new infections, bringing Hawaii’s totals since the start of the pandemic to 435 fatalities and 27,320 cases.

Two of the latest deaths were a man in his 60s and woman in her 90s with underlying conditions on Oahu. The two others, a man in his 60s, and a woman in her 80s, also with underlying conditions, were on Maui.

The new infection case count on Monday included 16 on Oahu, 24 on Maui, two on Hawaii island, one on Kauai and seven residents diagnosed out of state, officials said.

As of Wednesday, 318,542 doses of COVID-19 vaccine had been administered in the state, up more than 6,000 from the previous day, according to preliminary data from the state Health Department. Statewide, nearly 14% of Hawaii’s population has received at least one dose.

Hawaii is still in Phase 1-B of its vaccine rollout, which includes kupuna 75 and older, and front-line essential workers.

CVS Health on Wednesday said starting today it would offer COVID-19 vaccines at four new Longs Drugs locations in addition to the ones initially announced, through its Federal Retail Pharmacy Program.

Study’s findings

The CDC study examines a cluster that began in late June, when a fitness instructor, 37, who was asymptomatic at the time, unknowingly transmitted the virus to students in a high-intensity stationary cycling class. No one in that class wore a mask.

Another instructor, 46, took his class, and in turn transmitted the virus to his students in early July during personal training sessions and kick-boxing lessons at another fitness center prior to the onset of symptoms.

Both instructors tested positive for COVID-19, and the second one was later hospitalized in intensive care.

Investigators observed no transmission at a third gym, where the first instructor, wearing a mask, taught an hourlong yoga class more than two days prior to symptom onset.

Altogether, the Health Department said more than 30 participants tested positive for COVID-19 from this cluster. Researchers said the number may have been much higher since some who were asymptomatic were not tested.

At the time, face masks were not required in fitness centers, and community transmission in Hawaii was also low, at a daily average of two to three cases per 100,000 individuals.

Since July 22, Honolulu’s amended rules have required all people to wear face coverings in fitness facilities, whether exercising or not.

The study found that the rate of transmission was highest on the day of symptom onset for both instructors, which is consistent with findings from a previous study.

In addition, the transmission occurred even though the fitness bikes were spaced at least 6 feet apart, and researchers believe it was “likely facilitated by extended close contact, poor room ventilation, and not wearing face masks.”

Researchers believe that shouting instructions and encouragement throughout the one-hour class may have “contributed to transmission as aerosol emission during speech has been correlated with loudness.”

To reduce coronavirus transmission in fitness facilities, the study recommended that gyms enforce consistent and correct mask use and physical distancing of at least 6 feet between all people.

There should also be a limit on physical contact, class size and crowded spaces.

In addition, facilities should improve ventilation by maximizing fresh air, increasing filter efficiency, using portable air cleaners, and ensuring fans do not direct air from one patron to another.

Also, gyms need to offer plenty of opportunities for “hand hygiene” through hand sanitizing stations, and should constantly remind patrons and staff to stay home when ill.

When all is said and done, offering exercise activities entirely outdoors or virtually could further reduce risks of transmitting the coronavirus.

The study, “Community Transmission of SARS-CoV-2 at Three Fitness Facilities — Hawaii, June–July 2020,” was published Wednesday in CDC’s Morbidity and Mortality Weekly Report.

CDC also offers public guidance on the use of gyms, fitness centers and studios.