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Forecasting of Influenza Activity and Associated Hospital Admission Burden and Estimating the Impact of COVID-19 Pandemic on 2019/20 Winter Season in Hong Kong
38 Pages Posted: 1 Dec 2023
More...Abstract
Background: Like other tropical and subtropical regions, influenza viruses can circulate year-round in Hong Kong. However, during the COVID-19 pandemic, there was a significant decrease in influenza activity. The objective of this study was to forecast influenza activity during the year 2020 and assess the impact of COVID-19 public health social measures (PHSMs) on influenza activity and hospital admissions in Hong Kong.
Methods: Using weekly surveillance data on influenza virus activity in Hong Kong from 2010 to 2019, we developed a statistical modeling framework to forecast influenza virus activity and associated hospital admissions. We conducted short-term forecasts (1-4 weeks ahead) and medium-term forecasts (1-13 weeks ahead) for the year 2020, assuming no PHSMs were implemented against COVID-19. We estimated the reduction in transmissibility, peak magnitude, attack rates, and influenza-associated hospitalization rate resulting from these PHSMs.
Findings: For short-term forecasts, mean ambient ozone concentration and school holidays were found to contribute to better prediction performance, while absolute humidity and ozone concentration improved the accuracy of medium-term forecasts. We observed a maximum reduction of 46·7% (95% CrI: 38·0% - 53·8%) in transmissibility, 75·4% (95% CI: 73·0% - 77·3%) in attack rate, 40·6% (95% CI: 17·2% - 53·7%) in peak magnitude, and 58·7% (95% CI: 55·2% - 61·6%) in cumulative influenza-associated hospitalizations during the winter-spring period of the 2019/2020 season in Hong Kong.
Interpretation: The implementation of PHSMs to control COVID-19 had a substantial impact on influenza transmission and associated burden in Hong Kong. Incorporating information on factors influencing influenza transmission improved the accuracy of our predictions.
Funding: Health and Medical Research Fund, Hong Kong
Declaration of Interest: BJC received honoraria from AstraZeneca, Fosun Pharma, GSK, Haleon, Moderna, Novavax, Pfizer, Roche, and Sanofi. The authors report no other potential conflicts of interest.
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