COVID-19 has had lasting effects on transit ridership, with the worst declines seen in high-income, better educated, urban neighborhoods. However, declines among immigrant and/or low-income households was well documented prior to the pandemic, as more gained access to private vehicles. This has created a unique challenge for transit agencies to bring riders back to transit in cases where they may have already switched to traveling by car or consciously chose to make fewer trips. To better understand ridership during the pandemic, we documented the recovery of bus ridership in Los Angeles County and its relationship with COVID-19 vaccinations between April and December 2021, before the Omicron COVID-19 wave. We then developed a statistical model that relates LA Metro bus ridership as a percentage of October 2019 levels with the percent of adults fully vaccinated by ZIP code. We tested whether the relationship between vaccinations and bus ridership varied by two events: first, the full reopening of businesses in California and second, the wave of COVID transmission caused by the subsequentDelta variant.

Public transportation has been blamed for facilitating the spread of COVID-19 in dense, urban areas. As a response to the COVID-19 pandemic, transit agencies have reduced service and implemented mask-wearing mandates and social distancing aboard transit. Some prior studies that address public transportation provide some evidence that negative COVID-19 outcomes are linked to high transit use. One early study of COVID-19 transmission on trains in China found that transmission is also affected by the density of passengers, seat spacing, and length of time traveled with other passengers aboard the trains.