UH researchers forecast ‘worst case’ COVID Delta variant spread


There is still potential for COVID-19 case growth in Hawaii, and unvaccinated residents will be the primary driver of its spread and resulting hospitalizations.

Those are the key takeaways identified by a University of Hawaii research team, funded by the National Science Foundation, as it revisits COVID-19 case numbers in Hawaii, taking into account the more contagious Delta variant and the return of pre-pandemic visitor numbers.

The team is lead by UH mathematics professor Monique Chyba, working in partnership with the Hawaii Pandemic Applied Modeling Work Group (HiPAM).

Among their observations:

  • Mutations are a cause for concern, especially the Delta variant, currently dominating in the U.S. Daily cases have been increasing in Hawaii, and doubling in the U.S. as of July 13, 2021 compared to June 23, 2021.
  • Cases had been trending downwards since late May, despite a lower vaccination rate, the end of the mask mandate for outdoors, and an influx of tourists. The numbers started to climb back up around July 7.
  • Cases have gone up despite a decrease in testing in July, which is cause for concern.
  • Among the four main identified variants of COVID-19, the Alpha variant was dominant in May but prevalence has fallen consistently since. The Delta variant is the only variant with increasing numbers today.

“Reopening and lifting mitigations measures such as mask mandate must be done cautiously,” the group reported. “While daily cases and hospitalizations are under control currently, a surge cannot be excluded, especially if restrictions are lifted too early.”

Just today, Los Angeles County announced that it would again require masks to be worn when indoors due to a surge in COVID cases there. This a month after a long-awaited and celebrated reopening.

“It can be clearly observed that the majority of hospitalizations are due to unvaccinated individuals,” they added. “Vaccination is key to controlling the spread of the virus!”

Chyba and her team also prepared a worst case scenario for Honolulu County, assuming vaccination rates stop at 65 percent of the population, and assuming that all new cases are the more contagious Delta variant.

The forecast shows daily new cases exceeding 150 and daily hospitalizations nearing 90 by November 2021.

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