Date of Award

January 2021

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Nathan D. Grubaugh


Coronavirus disease 2019 (COVID-19) was first diagnosed in the United States on January 15, 2020, in the state of Washington. Shortly after that, on February 29, 2020, the first case of COVID-19 was reported in New York City. From January 2020 through July 2020, there were 223,107 cases of COVID-19 that led to 18,787 COVID-19 related deaths in New York City alone. During this time, many left New York City to avoid contracting the virus or to return home. This travel seeded much of the transmission within the United States. We aimed to identify any international transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as well from New York City and quantify the number of lasting transmission events by combining traditional epidemiological methods with phylogenetic and genomic methods. By subsampling more than 450,000 SARS-CoV-2 genomes publicly available up to 2020-11-02, we estimated the number of times SARS-CoV-2 was introduced from New York City to various geographic regions, not including the United States. On average, there were 6.7 different transmission events from New York City to other regions of the world between January and July of 2020. On average, Western Europe had the most introductions from New York City, followed by Northern Europe. These results were somewhat expected based on air-travel data where we saw that most travelers from New York City flew to the Caribbean, Northern Europe, and Western Europe. Overall, this study helps show that outbreaks within the United States, such as the New York City outbreak, helped fuel the international transmission events.


This is an Open Access Thesis.

Open Access

This Article is Open Access