"The app collects daily information from individuals in the community about whether they feel well, and if not, their specific symptoms and if they have been tested for COVID-19," said senior author Andrew T. Chan, MD, PhD, Chief of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital (MGH) and Director of Cancer Epidemiology at the MGH Cancer Center. The app is designed to provide insights on where the COVID-19 hot spots are and new symptoms to look out for, and it may be useful as a planning tool to inform guidelines around self-isolation, identify regions in need of additional ventilators and expanded hospital capacity, and provide real-time data to prepare for future outbreaks.

The COVID Symptom Tracker was launched in the UK on March 24th and became available in the US on March 29th. Since launch, it has been used by more than 3 million people.

"This work has led to the development of accurate models of COVID-19 infection rates in the absence of sufficient population testing," said Dr. Chan. "For example, the UK government has acted upon these estimates by providing advanced notice to local health authorities about when to expect a surge of cases." Researchers are also using results from the app to investigate risk factors for infection, as well as the effects of COVID-19 on patients' health.

Dr. Chan also pointed out that the app does not have any contact tracing function in contrast with software that is being rolled out in the future by some states in collaboration with Apple and Google. "Our app is designed to be entirely voluntary so that they can share information about how they are feeling in a way that safeguards their privacy."

The team is asking individuals, even those who are feeling well, to download the app and participate in this effort to provide critically valuable information related to COVID-19. The study was conducted by a team led by researchers at Massachusetts General Hospital (MGH), King's College London, and Zoe Global Ltd.