Travel bans can delay the spread of the coronavirus disease 2019 (COVID-19) by a few days but efforts to reduce transmission of the virus such as hand washing and social distancing have a greater impact on controlling the pandemic, according to a new study.

The study, published March 6 in Science, was co-authored by Elizabeth "Betz" Halloran, a professor of biostatistics at the University of Washington School of Public Health. The study’s corresponding author Alessandro Vespignani is a professor at Northeastern University. 

”Travel restrictions alone do not really do much but delay the spread of the disease, and delaying is good because it slows things down. But this idea of reducing the transmissibility is really key,” Halloran said in a news release from the Department of Biostatistics. She is director of the Center for Inference and Dynamics of Infectious Diseases based at the Fred Hutchinson Cancer Research Center. Halloran is also director of the Summer Institute in Statistics and Modeling in Infectious Diseases, hosted by the UW School of Public Health's Department of Biostatistics.

The study’s modeling found that the travel ban in Wuhan, China, where the virus first emerged, delayed the spread of COVID-19 to other areas of mainland China by three to five days. The travel ban also reduced the number of infections that spread to other countries by nearly 80% for two to three weeks, after which the number of cases resumed its growth.

The study concluded that while travel restrictions have modest effects on the spread of the virus, transmission-reduction interventions will provide the greatest impact on mitigating the pandemic. These interventions include measures for early detection and isolation of cases, social distancing such as school closures, behavior change such as frequent hand washing, and public health awareness.