COVID-19 Transmission Potential and Policy Changes in Hawaii and Guam March 2020-April 2022

Document Type

Presentation

Presentation Date

11-2-2022

Abstract or Description

Introduction: We aimed to assess how the SARS-CoV-2 transmission potential changed over time in Hawaii and Guam, given the public health interventions, behavioral changes, vaccination rate, and the impact of the Omicron variant through estimating the time-varying reproductive number (Rt) and analyzing the Google mobility data from March 2020-April 2022.
Methods: Rt was estimated using the instantaneous reproduction number method utilizing the R EpiEstim package. Five categories (retail and recreation, grocery and pharmacy, parks, workplace, and residential) of Google mobility data of Hawaii were analyzed to assess the correlation between population mobility trends in each category with incidence case count and 1-week sliding window Rt.
Results: Hawaii had three waves (Summer 2020, Summer 2021, and Winter 2021), and the highest number of daily new cases was recorded in Winter 2021. The median Rt estimates of Hawaii fluctuated around 1 for most of the study period, except the Rt estimate temporarily reached 2 in December 2021 as the Omicron became dominant in the US. Guam had four waves (Spring 2020, Summer and Fall 2020, Summer 2021, and Winter 2021), and the highest number of daily new cases was recorded in Winter 2021. The median Rt estimates fluctuated around 1 most of the time and reached 3 in January 2022. All of the time-lag correlation coefficients between mobility trend and incidence case count were significant (p<0.0001), e.g., the retail and recreation category correlated positively (r=0.237), and the residential category correlated negatively (r=-0.144). All of the time-lag correlation coefficients between mobility trend and 1-week sliding window Rt estimates were significant (p<0.0001), e.g., the workplace category correlated positively (r=0.525), and the residential category correlated negatively (r=-0.445).
Conclusion: Hawaii and Guam experienced sustained COVID-19 transmission (Rt≥1) despite the best efforts of public health interventions. Increased mobility for work and social activities were associated with increased COVID-19 transmission.

Additional Information

Georgia Southern University faculty member, Isaac C.H. Fung co-presented COVID-19 Transmission Potential and Policy Changes in Hawaii and Guam March 2020-April 2022 in the The American Society of Tropical Medicine & Hygiene, Annual Meeting, November 2022.

Sponsorship/Conference/Institution

The American Society of Tropical Medicine & Hygiene, Annual Meeting

Location

Seattle, WA

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