Chu specializes in maternal immunization, with a particular focus on influenza and human orthopneumovirus.[5] She is part of Seattle Flu Study, a multi-institutional community-wide virus surveillance platform that began in 2018.[6][7] Traditionally, people rely on hospital admissions to know when the flu season begins and ends, but Chu believes that it spreads around the community through asymptomatic carriers who do not get admitted to hospital.[7] As part of this study, Chu collects nasal swab samples from patients to better "detect, monitor, and control outbreaks" in Puget Sound.[8][9] She makes use of a network of kiosks all around Seattle to collect these samples.[4] She then sequences the genome of influenza viruses to track the flu as it moves around the city.[10]
During the COVID-19 pandemic, Chu became concerned that human – human transmission of SARS-CoV-2 was occurring in Seattle. Whilst it would have been simple to repurpose the nasal swabs from the Seattle Flu Study to test for coronavirus disease, Chu was not given federal approval to do so.[8] In an interview with The New York Times, Chu said, “We felt like we were sitting, waiting for the pandemic to emerge. We could help. We couldn’t do anything,”.[8] In late February, Chu decided to test for coronavirus disease anyway, even without federal approval.[11][12] Not long after she started testing, Chu identified a positive coronavirus disease test in a local teenager with no relevant travel history.[8] Chu was the first physician in the United States to identify community transmission of coronavirus disease.[13]Eric Feigl-Ding, epidemiologist at the Harvard T.H. Chan School of Public Health, said that Chu “is a true American hero, [who] actually broke this epidemic identified in Washington state when no one else wanted her to test for the virus,”.[14] Despite this, Chu was told that she could not go on testing; because she did not have the correct clinical certification to run coronavirus disease tests.[8] Chu believes that community transmission had occurred well before active surveillance began.
The Seattle Flu Study partnered with public health officials to launch a Seattle Coronavirus Assessment Network, who collect nasal swabs from people across Seattle in an effort to understand the spread of coronavirus disease.[9] Chu shifted her research to focus on the identification of patients who had become infected with SARS-CoV-2.[6] In early March Chu was awarded permission from the Food and Drug Administration to start COVID-19 testing.[10] She conducted an investigation into the prevalence of coronavirus disease, enrolling participants online and rapidly distributing home testing kits. Kits were delivered with same-day delivery, sometimes within hours of people registering on the site, and samples were analysed within two days.[6] Alongside her own research program to better understand the transmission and biology of SARS-CoV-2, Chu is involved with the National Institutes of HealthCOVID-19 vaccine trials and clinical trials into the use of antiviral drugs.[15]