State-level COVID-19 lockdown stringency associated with increases in motor-vehicle mortality rates

Area of Science:

• Public Health
• Epidemiology
• Traffic Safety

Background:

• Motor-vehicle collision fatalities significantly increased nationwide during the COVID-19 pandemic.
• Substantial state-level variations in fatality rates were observed.
• The study investigated the link between COVID-19 public health policy stringency and these fatality rate changes.

Purpose of the Study:

• To examine the relationship between state-level COVID-19 public health policy stringency and changes in motor-vehicle fatality rates.
• To identify specific behaviors and age groups affected by varying policy stringency.

Main Methods:

• Ecological cross-sectional time-series study utilizing National Highway Traffic Safety Administration (NHTSA) Fatality and Analysis Reporting System (FARS) data.
• Exposure: Oxford University COVID-19 Government Response Tracker (OxCGRT) Stringency Index for lockdown policies.
• Outcome: Motor-vehicle collision mortality rate ratios (2020-2021 vs. 2018-2019), analyzed with univariate linear regression.

Main Results:

• A significant positive association was found between COVID-19 policy stringency and increased motor-vehicle mortality rates for intoxicated driving (β=0.025, p=0.02) and unrestrained/unhelmeted driving (β=0.013, p=0.03) among adults aged 21-34.
• Eleven of the remaining 14 analyzed groups showed a positive association, but these did not reach statistical significance.
• The findings suggest limited broad associations but highlight specific risks for younger adults.

Conclusions:

• Limited evidence connects overall state-level COVID-19 policy stringency with motor-vehicle collision fatalities.
• Adults aged 21-34 experienced higher rates of fatalities due to intoxicated and unrestrained/unhelmeted driving during stricter lockdown periods.
• Targeted prevention strategies are warranted for susceptible subpopulations experiencing behavioral changes under social restrictions.