Allisandra Kummer
Allisandra G. Kummer is a 1st year PhD student in the Department of Epidemiology and Biostatistics at the Indiana University School of Public Health-Bloomington with a minor in Informatics and is a research assistant in the Laboratory for Computational Epidemiology and Public Health. Her goals and research interests focus on computational and mathematical modeling of infectious disease dynamics and the role of social human behavior in disease transmission. Her ambition is to develop models that inform public health policy and infectious disease surveillance. In addition, she wishes to pursue a career in academia to share her passion for research and inspire future epidemiologists.
Measuring the Seasonality of Human Contact Patterns and Its Implications for the Spread of Respiratory Infectious Diseases
Considerable uncertainties surround seasonality of respiratory infectious diseases. To which extent the observed seasonality is associated with biological reasons (e.g., virus survival rates, host immune dynamics) or human behavior remains unclear. We investigated the association between temperature and human contact patterns using data for 965 individuals collected through a contact diary-based survey between December 24, 2017 and May 30, 2018 in Shanghai. We fit the data to a negative binomial regression and found a significant inverse relationship between number of contacts and temperature seasonal trend (p=0.003) and temperature daily variation (p=0.009), with contacts increasing from 19.6 (95%CI: 14.9-22.2) in December to 24.4 (95%CI: 19.0-28.0) in January and declining to 10.9 (95%CI: 10.1-11.9) in May. This seasonal trend in number of contacts translates into a seasonal trend in the basic reproduction number – mean number of secondary cases generated by a typical infector in a fully susceptible population. By setting the basic reproduction number at 1.4 on December 24, weekly mean estimates showed a clear increasing trend during the fall from 1.14 (95%CI: 0.78-1.39) in October to 2.02 (95%CI: 1.60-2.35) in February and remaining below 1 in the summer. Epidemic dynamics comparable with those of seasonal influenza are obtained through homogenous, compartmental model simulations when the infection is seeded in October; however, their dynamics become more complex when seeded after February (e.g., double peaks or no epidemic in summer). Our findings indicate a distinct seasonal trend among human contact patterns and highlight a behavioral mechanism contributing to seasonality of respiratory infectious diseases.
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