Hawaii’s response to the COVID-19 pandemic has been thrown another curveball, with several studies, including one involving U.S. veterans, showing a decline in vaccine efficacy over a six-month period.

In a recent study published in Science, researchers analyzed data from nearly 800,000 veterans collected by the Veterans Health Administration from February to October to see how effective the three available COVID-19 vaccines were against the coronavirus.

While the vaccines remained effective at preventing death from the coronavirus, researchers found a loss of efficacy in all three to varying degrees after six months.

The most dramatic decline was with the single-dose Johnson & Johnson vaccine, whose efficacy declined from 86% in March to 13% in September.

For the Pfizer vaccine, the e ffectiveness fell from 87% to 43% during the same period; and for Moderna, from 89% to 58%.

What does that mean for Hawaii, which has one of the highest vaccination rates in the nation, with 72.1% of the population fully vaccinated, and some of the most restrictive measures in place to protect its residents from the coronavirus?

It means that booster doses, which federal authorities say can now be mixed, will play a vital role in the ongoing battle against the coronavirus heading into the holiday season.

Whether more Americans should receive them, and when, is currently being debated at the federal level, with Pfizer having asked the U.S. Food and Drug Administration to allow boosters for anyone 18 or older. Some U.S. states, such as Colorado and California, went ahead and gave all their adult residents the green light to get COVID-19 vaccine boosters if at least six months have passed since their initial vaccine series.

The Hawaii Department of Health has no formal plans to follow suit, but Dr. Elizabeth Char, department director, said the state will continue to offer COVID-19 booster shots to everyone who qualifies and that those recommendations are quite inclusive.

“We have plenty of doses and a good supply of vaccines,” she said. “You can get a booster shot at hundreds of locations across the state.”

The Centers for Disease Control and Prevention currently recommends Moderna and Pfizer boosters for those 65 and older, or anyone 18 and up with underlying health issues or an elevated risk of exposure due to work or living situations.

Anyone who received a single- dose Johnson & Johnson vaccine more than two months ago should also get a booster shot.

As of Friday, DOH reported that nearly 126,900 third doses had been administered statewide, representing nearly 10% of the population.

Lt. Gov. Josh Green said he supports making the boosters available to all adults who want one as soon as possible to keep Hawaii on the right path.

“Right now we’re experiencing a good and reliable decrease in hospitalizations, which is the best benefit of the vaccine,” he said.

On Friday, Green said 46 COVID- 19 patients were hospitalized compared to a peak of 448 in early September.

The 46 included 34 who were unvaccinated and 12 who were fully vaccinated, with Green noting that a growing percentage of vaccinated COVID-19 patients — closer to 25% compared to 10% previously — are now ending up in hospitals.

The vaccines, however, still prove to be highly effective at protecting people against hospitalization and death, according to a new DOH analysis of breakthrough coronavirus infections.

GOVERNMENT leaders and infectious disease specialists have mixed views of the level of restrictions needed to keep COVID-19 in check in light of the research showing a decline in vaccine efficacy over time.

The issue of waning vaccines comes as no surprise to Tim Brown, an infectious disease modeler and senior fellow at the East-West Center in Manoa, who monitored studies from Israel and Singapore several months ago with similar results.

Brown said Hawaii is in a “sweet spot” right now, where the majority of the adult population has been vaccinated, which, combined with those who acquired immunity through infection, puts the state in a good position.

The seven-day average of daily coronavirus cases stood at 101 on Friday, and the average positivity rate was 1.7%. The volume of cases reached a plateau as of mid-October, while vaccination rates continue to climb.

But for Brown, waning vaccine efficacy only means masks and other restrictions are still needed to prevent coronavirus transmission in the months and possibly years ahead, especially with the highly contagious delta variant present.

“Those who got vaccines back in January and February and haven’t been boosted yet are probably only getting 50% to 60% effective protection against infection,” he said. “So yes, they’re less at risk than an unvaccinated person, but they’re still at some risk.”

Brown warned Hawaii residents to be especially cautious approaching the holiday season, when travel is popular.

“People have consistently underestimated this virus from Day One,” he said. “We’re constantly declaring victory and having the rug … pulled out from right under us. Those of us who have been watching this carefully know it’s stupid to declare victory.”

A prime example is when the CDC said vaccinated people could drop their masks indoors just as the delta surge was on the horizon and then reversed course, he said.

“That was exactly the wrong public health message to send,” Brown said. “The proper public health message is if you’re vaccinated you’re protected against severe illness, but you can still potentially contract or transmit the virus, so for now you should continue to wear your mask.”

Green agreed that indoor masking is still necessary, considering the surges occurring in Europe and other U.S. states.

Appearing on the Honolulu Star-Advertiser’s “Spotlight Hawaii” livestream program Friday, Green said indoor masking would be the last COVID-19 restriction to go, preceded by the lifting of current travel restrictions.

Eventually, he said, restrictions will be lifted, possibly in two- to three-week increments so residents can return to a sense of normalcy, which is important for their psychological and social well- being.

As long as people are getting vaccine boosters at an adequate rate and there are no hospitalization surges, the state should be able to ease restrictions, according to Green. Hawaii is on course to reach 85% to 88% immunity through vaccinations, with 6% immunity from infection.

“We have to, at the same time, return to what matters in life and what makes sense,” he said. “You cannot live under a cloud of fear forever.”

Brown, however, urged caution in lifting restrictions too quickly, based on what’s happened in other places such as the United Kingdom, Denmark and Singapore, where restrictions were dropped then reinstated after the virus resurged and hospital beds filled up again.

Safe Travels Hawaii also should require a negative COVID-19 test within 72 hours for all vaccinated travelers from the mainland as an additional safety net, he said.

And the state needs a long-term strategy for dealing with the pandemic — from planning better ventilation in indoor spaces to improving access to rapid testing so that those who contract COVID-19 get timely treatments, whether it’s antiviral pills or monoclonal antibodies — and a steady supply of vaccines and boosters.

Brown said he’s learned there is no magic bullet for ending a pandemic, and vaccines alone are not the answer.

“The mindset has to shift from finding the magic bullet to actually having a plan for dealing with this going forward, for actually living with COVID in our community,” he said.

Health officials continue to emphasize the importance of getting children ages 5 to 11, who became eligible for the Pfizer vaccine earlier this month, their shots. As of Friday, DOH said about 6% of that age group in Hawaii received the first of the two-dose Pfizer vaccine, which is given three weeks apart.

Char said while the studies show boosters are important, getting children vaccinated is DOH’s current priority.

“The priority right now is getting those 5 to 11 years old vaccinated to help further mitigate the effects and spread of COVID in our community, and help us to get back to where we want to be,” she said in a statement. “Thankfully, we have enough shots to do both the boosters and immunize the kids 5 to 11 years of age.”