As the pace of Hawaii’s COVID-19 vaccinations slows, some say that the state should consider people who caught the coronavirus in its analysis of how much progress Hawaii has made toward herd immunity — and by extension, when the state should resume normalcy.
Honolulu is currently in Tier 5, which includes limitations on social gatherings, restaurant patrons and more. The governor says he will not remove pandemic restrictions until the state reaches a 70% vaccination rate.
As of Tuesday, more than 58% of people in the state have completed their vaccine doses. At least 65% have received at least one vaccine shot, far more than most states.
“That’s fantastic,” says Abba Gumel, a professor at Arizona State University who specializes in mathematical biology and has been modeling COVID-19 herd immunity in the U.S.
But vaccination progress has slowed in Hawaii and it’s unclear how long it will take to hit that 70% target. Recent surveys found 9% to 12% of Hawaii’s residents don’t plan to get vaccinated at all. Others lack access to the vaccine, although the state has been focusing on improving access and education for people in rural communities.
Lt. Gov. Josh Green is a proponent of doing surveillance testing to figure out how many people who caught COVID-19 got vaccinated and then adding the number of people who got the virus to the state’s calculation of how many residents have immunity.
“I feel very strongly it would be smart to tease out the number of people who had COVID-19 and developed natural immunity out of the population because that does contribute to how safe or vulnerable we are,” Green said.
But that comes with a risk of double-counting people who got both sick and vaccinated, including Green himself. The Centers for Disease Control and Prevention recommends that everyone who caught coronavirus get vaccinated.
Green thinks surveillance testing will lessen the risk of double-counting. He said that much of Hawaii’s population includes children under 12 who aren’t eligible for the vaccine yet and noted that Hawaii is unusual in its target of vaccinating 70% of the state population instead of 70% of those eligible for vaccines.
“It’s not imperative that we do this but the more information we have, the better decisions we should make,” Green said. “If we actually have achieved adequate immunity … then we should back off of restrictions and open up.”
But there’s a lot of reasons why Ige’s Department of Health is hesitant to do what Green is suggesting. Brooks Baehr, a spokesman for the state agency, says there were so few coronavirus cases in Hawaii that adding them wouldn’t make a big difference in terms of reaching that 70% target.
“Hawaii has done well with controlling cases during the COVID-19 pandemic, so the number of confirmed cases in our state is quite small in proportion to those vaccinated, and would have minimal impact on our overall picture of population immunity,” Baehr said in an email.
But Green thinks the statewide COVID-19 case count is a significant undercount of how many people in Hawaii actually got the coronavirus, and thus have immunity.
Tarquin Collis, chief of the Department of Infectious Diseases at Kaiser Permanente, says it’s possible five to 10 times as many people may have caught COVID-19 in Hawaii than the official reported numbers.
“A lot of people never come to medical attention especially when it carries stigma and workplace exclusion, and a lot of people are just asymptomatic,” Collis said.
That’s based on studies from other locations, he said. He added it’s “not at all unreasonable” to consider people who caught the virus in the state’s analysis of how many residents have immunity. But actually doing so is challenging.
“The short version is that it’s not as simple as a yes or no,” Collis said.
Jim Ireland, director for the city’s emergency services department, agrees that it’s helpful to consider natural immunity but that it’s complicated.
“I think it should definitely be a consideration in the overall strategy for reopening but how you use that data is not for me to say,” he said. “That’s part of the equation, that’s part of the data that should be considered but it’s a little less concrete.”
The simplicity of vaccination rates is one reason why the health department is sticking with that metric.
“In the end, since herd immunity is determined by the virus and we don’t know exactly what percentage of population coverage will get us there, it is best that we focus on simple, clear vaccination targets that will bring us measurably closer to the goal of herd immunity, while watching for the desired outcomes of fewer cases, clusters, hospitalizations, and deaths,” Baehr wrote in an email. “Those outcomes are what will really tell us we have reached herd immunity.”
Baehr said another reason the state isn’t counting people who caught the coronavirus in its analysis of immunity is that it’s unclear how long such immunity lasts, and immunity from vaccination is believed to be stronger than immunity from having had the virus.
Gumel from Arizona State University said more data and clinical trials are needed.
“The jury is still out on the level of protection natural immunity (provides),” he said.
Gumel said people who caught the virus “should contribute somehow to herd immunity,” but noted that there’s a lot of uncertainty about how people who got sick from the coronavirus will react to new variants.
There’s also the fact that state borders are porous. Even if Hawaii does very well with vaccinations, the increase in tourism and movement of residents who travel out and back into the state increases the possibility that new variants will be introduced.
While Gumel said it makes sense to set a vaccination target of 70% of the eligible population, he doesn’t think Hawaii should let its guard down until 65% of the country is vaccinated against COVID-19.
“Hawaii is leading the charge — 65% — we also have to think, the rest of the country has to follow,” Gumel said. “Then we can all have a collective sigh of relief.”
“It only takes a few cases to kickstart an epidemic,” he added.
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