COVID-19 exacted a higher infection-related and excess all-cause death toll from the United States than from 20 peer countries throughout the pandemic but had less of an impact in the most-vaccinated states in the Delta and Omicron surges, suggests a study published late last week in JAMA.
The United States had 155,000 to 466,000 more deaths than peer nations in the second half of 2021 and early 2022, the investigators estimated.
Both COVID-related and all-cause deaths
Researchers from the Brown School of Public Health and the University of Pennsylvania compared the United States overall, the 10 most- and least-vaccinated states, and 20 Organization for Economic Co-operation and Development (OECD) countries with a population exceeding 5 million and a per-capita gross domestic product higher than $25,000 in 2021.
The team analyzed the US COVID-19 death rate, the all-cause death rate, and vaccination data from the Centers for Disease Control and Prevention (CDC) and, for other countries, mortality data from the World Health Organization, all-cause mortality data from the OECD, and vaccination data from Our World in Data.
The COVID-19 per-capita death rate was calculated for the Delta variant from Jun 27, 2021 (week 26), to Dec 25, 2021 (week 51), and for Omicron from Dec 26, 2021 (week 52), to March 26, 2022 (week 12).
To estimate excess all-cause deaths, the researchers compared mortality in each period with that in 2015 to 2019. For both periods, they estimated potential US lives saved if the country had experienced the death rates seen in peer countries.
Most-vaccinated states fared best
Two-dose COVID-19 vaccination rates in the 10 most-vaccinated US states as of Jan 1, 2022, ranged from 71.3% in Washington, DC, to 79.0% in Vermont, for an average of 73% coverage. The other top-tier states were (from lowest to highest vaccination rate) New Jersey, Maryland, New York, Massachusetts, Hawaii, Connecticut, Maine, and Rhode Island.
Vaccination rates in the 10 least-vaccinated states ranged from a low of 48.9% to 53.4% in Indiana, for an average 52% coverage. The other bottom-tier states were (from lowest to highest vaccination rate) Wyoming, Mississippi, Louisiana, Idaho, Georgia, Arkansas, Tennessee, and North Dakota.
COVID-19 vaccination rates in peer countries ranged from a low of 64% in Israel to 82% in South Korea. Overall US vaccination coverage was 63%. The other peer countries were Canada, Australia, New Zealand, and others in Europe, Asia, and the Middle East.
US per-capita COVID-19 deaths overall and in both state subgroups significantly exceeded those of all peer countries, with 370,298 COVID-19 deaths (112/100,000) during Delta and Omicron (61/100,000 and 51/100,000, respectively). But COVID-19 death rates were significantly lower in the 10 states with the highest vaccination coverage (73% coverage; 75 deaths/100,000 people) than those in the 10 least-vaccinated states (52% coverage; 146/100,000).
Excess all-cause mortality in the United States exceeded COVID-19 mortality (145/100,000) and that of peer countries, as did excess all-cause death in the 10 US states with the lowest vaccine uptake. In the 10 most-vaccinated states, however, excess all-cause death rates were similar to or less than that of several peer countries during both Delta and Omicron.
While excess all-cause death rates in the most-vaccinated states significantly exceeded those of many peer countries amid Omicron, those states saw significantly lower all-cause than COVID-19 death rates in that wave (29/100,000 and 47/100,000, respectively).
As many as 466,000 avoidable deaths
If the COVID-19 death rate in the rest of the United States would have been the same as that of the 10 most-vaccinated states, the country may have been able to avert an estimated 122,304 deaths. Similarly, 266,700 deaths may have been avoided in the United States if its excess all-cause mortality rate was the same as that in those 10 states from Jun 27, 2021, to Mar 26, 2022.
If the United States had matched the death rates of peer countries, an estimated 154,622 to 357,899 COVID-19 deaths and 209,924 to 465,747 all-cause deaths may have been prevented.
"The US continued to experience significantly higher COVID-19 and excess all-cause mortality compared with peer countries during 2021 and early 2022, a difference accounting for 150,000 to 470,000 deaths," the authors wrote.
The muted difference in the 10 most-vaccinated states could also have been influenced by high vaccination in peer counties, more targeted vaccination to older age-groups, and differences in health and social infrastructure, they said.
"This study also highlights the value of excess mortality in understanding effects of COVID-19," the researchers concluded. "Excess all-cause mortality began to fall below COVID-19 mortality in several countries and highly vaccinated states during Omicron, perhaps owing to reductions in non–COVID-19 deaths. However, cross-location differences may also reflect differences in COVID-19 death coding."