In a recent study posted to the medRxiv* preprint server, researchers estimated the coronavirus disease 2019 (COVID-19)-associated mortality in the United States (US) between January 3, 2020, and September 26, 2021.

During the summer of 2021, America was described as "two Americas" in the context of the COVID-19 pandemic: one with a strong demand for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination and the other with high hesitancy towards vaccination, which later progressed to widespread resistance to vaccinations and using masks. The second characteristic was most frequent in the highly populated South regions and rural areas of the US.

SARS-CoV-2 cases, hospital admissions, and mortality rose substantially in this second America during the summer. However, the evolution of SARS-CoV-2-related mortality in the US is not clearly understood.

About the study

In the present study, the researchers determined when the regional differences in the COVID-19 pandemic emerged in the US and their temporal relationship with vaccination. For this, the team evaluated the state-level weekly excess death rates prepared by the Centers for Disease Control and Prevention (CDC) for the US during January 3, 2020, and September 26, 2021. The "excess mortality rates" are the difference between the total deaths and the anticipated mortality based on previous periods.

The US states were aggregated into four regular Census regions since other ad hoc clustering may accentuate or obscure differences. Based on a preliminary review of the data, five periods were designated with significantly distinct patterns of excess deaths. Further, the vaccine coverage rates were estimated using a previously established data set.

Findings

The results demonstrate that the US experienced 895,693 COVID-19-related excess mortalities between January 3, 2020, and September 26, 2021, which was 26% higher than the reported deaths. The proportion of COVID-19-associated excess deaths was the highest in the Northeast US states, followed by South and West. Nearly 43% of the projected mortality occurred during October 4, 2020, and February 27, 2021.

Before May 31, 2020, above half of the deaths occurred in the Northeast regions, where 17% of the US population lived. Further, around 48% of the mortalities were in the South during the same period, where 38% of the US population lived. Since May 31, 2020, while the South demonstrated 26% higher COVID-19-related deaths than the entire US, the Northeast experienced 42% lower rates than the national stats.

No mortalities were avoidable during the first period, January 2 to May 30, 2020, since significant COVID-19 mitigation measures were not known during this period. However, over 316,234 of the COVID-19-associated mortalities during May 31, 2020, and September 26, 2021, were avoidable if other regions had mortality rates similar to the Northeast. Nearly 63% of avoidable mortalities happened during May 31, 2020, and February 2021, and a further 36% between June 27 and September 26, 2021. Moreover, above half of the avoidable deaths occurred in the South.

Conclusions

The study findings indicate that considerable differences in excess COVID-19-related mortalities have existed in the US from the start of the COVID-19 pandemic. The most striking variation was observed between the North and South regions of the US. Although the first wave of the SARS-CoV-2 pandemic was the most concentrated in the North, around half of the excess deaths occurred in the South since May 2020.

The COVID-19-related mortality rates were the lowest in the Northeast regions of the US, which had the highest vaccination rates, whereas the South had the low vaccination coverage and highest SARS-CoV-2-associated deaths in the summer of 2021. Thus, the high rates of excess death across the South can be correlated with the hesitancy towards vaccination and mask usage.

The study presents a variation in the impact of COVID-19 across the US regions, though the reasons are not fully comprehended. Further, excess mortality studies will be beneficial in understanding the COVID-19-associated death pattern in rural and urban areas between the states and within socio-demographic groups. Overall, the study highlights the need for a comprehensive COVID-19 strategy that includes population-level restrictions and vaccinations to halt the ongoing SARS-CoV-2 pandemic.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Shanet Susan Alex

Shanet Susan Alex, a medical writer, based in Kerala, India, is a Doctor of Pharmacy graduate from Kerala University of Health Sciences. Her academic background is in clinical pharmacy and research, and she is passionate about medical writing. Shanet has published papers in the International Journal of Medical Science and Current Research (IJMSCR), the International Journal of Pharmacy (IJP), and the International Journal of Medical Science and Applied Research (IJMSAR). Apart from work, she enjoys listening to music and watching movies.