During the COVID-19 pandemic, free on-demand testing was promoted in the US. This study was undertaken to support or refute the hypothesis that negative SARS-CoV-2 tests led to travel that exposed travelers to the virus in US states.

Data on daily trips outside households based on cell phone movement were matched by date to negative tests, positive tests, subsequent COVID-19 cases, and deaths lagged at various intervals in 49 US states during the first 16 months of the pandemic. Least-squares regression of weekly trips as a function of prior trips, negative tests, and cases was examined. Cases 10-14 days after negative tests and deaths 20-25 days later as a function of previous trips and positive tests were also assessed by least squares regression.

Increases in negative tests predicted increases in trips but trips declined as cases increased. Changes in trips predicted short-term changes in cases and deaths. The data closely fit the models.

Surges in cases and deaths from COVID-19 were likely a partial result of on-demand testing, without sufficient contact tracing and quarantine, which misled those who tested negative into thinking that it was safe to travel.