On Apr. 23, 2023, the most comprehensive state-by-state analysis of the impacts of COVID-19 across the USA, published in The Lancet, revealed the underlying reasons why the pandemic played out in vastly different ways across the country.

The new analysis found that between January 1, 2020, and July 31, 2022, cumulative COVID-19 death rates varied widely across the USA, with Hawaii and New Hampshire having the lowest standardised rates (adjusted for age and comorbidities; 147 and 215 deaths per 100,000, respectively) and Arizona and Washington, DC having the highest (581 and 526 deaths per 100,000, respectively).

The researchers stress that states with the lowest standardised COVID-19 death rates came from different geographies and partisan influence. And the same is true for the states with the highest standardised COVID-19 death rates.

The study is the first time researchers have comprehensively examined the driving forces behind wide variations in SARS-CoV-2 infections and COVID-19 deaths across all states over a lengthy period and adjusted for factors outside policymakers’ immediate control (e.g., age, population density, key comorbidities).

Using state-level data from public databases, researchers analysed government policy responses and population behaviours (e.g., mask use, vaccination, mobility) in all 50 US states and Washington, DC, from January 1, 2020, to July 31, 2022, to assess states’ efforts in mitigating the impact of SARS-CoV-2 infections and COVID-19 deaths, and whether better COVID-19-related outcomes offset economic, educational, and employment losses.

Results of this analysis were used to answer five-key policy questions that have emerged during the pandemic around wide state-by-state variations in COVID-outcomes: 1) the role of social, racial, and economic inequities; 2) whether states with greater health care and public health capacity performed better; 3) the influence of politics on the results; 4) whether states that imposed more policy mandates and sustained them longer did better; and 5) whether there were trade-offs between a state having fewer cumulative SARS-CoV-2 infections and total COVID-19 deaths and better economic and educational outcomes.

The analyses found that US states with higher poverty, lower rates of educational attainment, less access to quality health care, and lower levels of interpersonal trust (trust in others) experienced disproportionately higher rates of SARS-CoV-2 infections and COVID-19 deaths.