A recently published study in JAMA provides the estimates of coronavirus disease 2019 (COVID-19)-related mortality and excess all-cause mortality in the US and 20 peer countries during the delta and omicron waves of infection.
The COVID-19 pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused significant damage to the healthcare and business sectors worldwide. The highest number of COVID-19 mortalities was observed in the United States. The country has also experienced higher all-cause mortality than other countries in 2020.
With the rapid deployment of effective COVID-19 vaccines, a significant decrease in new cases and mortality has been observed worldwide. However, with the emergence of new virus variants, a gradual decline in vaccine effectiveness has been noted over time.
In the current study, scientists compared COVID-19-related mortality and excess all-cause mortality in the United States and 20 Organization for Economic Co-operation and Development (OECD) peer countries during the delta and winter omicron waves.
The scientists collected the US COVID-19-related mortality, all-cause mortality and immunization data from the US Centers for Disease Control and Prevention (CDC). The analysis considered all US data and the ten most and least vaccinated states.
For other peer countries, they collected COVID-19 mortality data from the World Health Organization (WHO), all-cause mortality data from the OECD databases, and immunization data from Our World in Data.
Mortality rates were estimated over two time periods: the delta-dominated period (June 2021 to December 2021) and the omicron-dominated period (December 2021 to March 2022). Mortality in each period was compared to mortality in 2015-2019 to estimate excess all-cause mortality.
Estimated US COVID-19-related mortality rates were 61 per 100,000 and 51 per 100,000 during the Delta and Omicron periods, respectively. The US all-cause mortality rate and the federal immunization status mortality rate were significantly higher than those observed in other comparator countries.
A significant difference in mortality rates was observed between high and low immunization coverage states. In particular, states with high immunization coverage (73%) had 75 deaths per 100,000 people; in contrast, states with low immunization coverage (52%) had 146 deaths per 100,000 people.
The overall mortality rate in the US was estimated at 145 per 100,000 people, which was significantly higher than other comparable countries. However, the excess all-cause mortality rate in states with high immunization coverage was comparable to that in other peer countries during the combined Delta and Omicron period.
Looking at each period individually, significantly higher all-cause mortality was observed in these states during the Omicron period compared to many peer countries. However, significantly lower all-cause mortality than COVID-19 mortality was observed in these states during this wave.
Estimated Mortality Rates
According to the predictions, made by matching US COVID-19 mortality to that of the ten most vaccinated states, the country would have prevented 122,304 deaths during the combined Delta and Omicron period.
Similarly, assuming identical excess all-cause mortality between the US and the top ten most vaccinated states, the US would have prevented 266,700 deaths over the entire period.
Assuming identical mortality rates between the US and other peer countries, the US would have prevented 154,622-357,899 deaths in COVID-19 and 209,924-465,747 in all-cause mortality.
The study estimates that the US experienced significantly higher COVID-19 mortality and excess all-cause mortality than other peer countries in 2021 and early 2022. However, the states with high vaccination coverage do not reflect a similar situation. This finding underscores the importance of COVID-19 vaccination in reducing mortality.