COVID-19 continues to be a leading cause of death in the U.S. in September 2021

COVID-19 was the third leading cause of death across most of 2020, but in December 2020 and early 2021, the illness surged and briefly became the number one leading cause of death in the U.S., far surpassing even cancer and heart disease deaths in those months.

With the rapid uptake in vaccinations in the months when vaccines first became widely available, COVID-19 deaths fell sharply. COVID-19 dropped to the number 7 leading cause of death in the U.S. in July 2021.

However, with the more infectious COVID-19 Delta variant, insufficient vaccination rates, and local and state governments easing up social distancing restrictions, COVID-19 cases, hospitalizations, and deaths increased again. Vaccination rates are particularly lagging for younger adults and people living in certain states. As of October 7, 2021, about 78% of adults (ages 18+) in the U.S. have received at least one COVID-19 vaccine dose and over 50 million adults remain unvaccinated.

This brief revisits where deaths from COVID-19 rank among leading causes of death in the U.S. We find that COVID-19 was the second leading cause of death in September 2021. We also find in September COVID-19 was the number 1 cause of death for people age 35-54 and among the top 7 leading causes of death for people in other age groups.

We also estimate how many COVID-19 deaths were among unvaccinated adults and could have been prevented since June 2021 when safe and effective COVID-19 vaccines became widely available to all adults in the U.S. From June through September 2021, approximately 90,000 COVID-19 deaths among adults likely would have been prevented with vaccination.

COVID-19 was the 2nd leading cause of death in the U.S. in September 2021

Looking at the most recent data available on deaths from COVID-19 and other causes, we estimate that COVID-19 was the number 2 leading cause of death in the U.S. in September 2021. Deaths from other causes represent the daily average deaths from January through June of this year. (Average daily deaths from accidents and suicides in the chart above are from 2020, as 2021 data are not yet available.)

The number of daily deaths from COVID-19 had decreased remarkably from the once staggering 3,135 deaths per day in January 2021 but started increasing again, in August 2021, with the Delta variant wave. In September 2021, COVID-19 took the lives of 1,899 people per day on average. By comparison, heart disease, which is typically the number one cause of death in the U.S. each year, leads to the death of about 2,000 Americans per day, and cancer claims about 1,600 American lives per day, on average.

As of October 2021, COVID-19 deaths are declining. However, an average of over 1,600 people per day continued to die of COVID-19 in the first week of October 2021, even as safe and effective vaccines have been free and widely available to adults in all states and D.C. since early May 2021. An overwhelming majority of COVID-19 deaths in the U.S. have been among unvaccinated people, as we discuss below.

The cumulative number of deaths attributed to COVID-19 in the U.S. from the start of the pandemic through October 7, 2021 is 710,659.

COVID-19 rank fell to number 7 among leading causes of death in July but is back up to number 2 in September 2021

The chart above combines data on COVID-19 mortality rates from KFF’s tracker with data from the Centers for Disease Control and Prevention (CDC) to examine weekly counts of death by jurisdiction and cause of death and monthly provisional counts of deaths by select causes. Deaths from COVID-19 and other causes in the chart above are the average daily deaths in each month of 2020 and 2021.

For most of 2020 and in early 2021, COVID-19 was one of the top three leading causes of death in the U.S. As vaccination rates increased, average daily deaths from COVID-19 decreased since the peak in January 2021. However, COVID-19 deaths have been increasing again recently. COVID-19’s rank among leading causes fell to number 7 in July 2021. Then, COVID-19 rose to the number 3 leading cause of death in August 2021, and up to number 2 in September 2021.

COVID-19 was the number 1 leading cause of death for people ages 35-54 years in September 2021

To rank COVID-19 among other leading causes of death by age groups, we looked at COVID-19 deaths for each age group in 2021 and the most recent available data for other rankable age-specific leading causes, including congenital disorders and perinatal conditions that mostly affect children.

COVID-19 was among the top 7 leading causes of death for all age groups in September 2021. COVID-19 killed more people age 25-34, 35-44, and 45-54 in August and in September than it did in any other month prior, despite the widespread availability of vaccines.

In September 2021, COVID-19 ranked as the number 1 leading cause of death above accidents for people age 35-44, number 1 above cancer for people age 45-54, number 2 above suicide for people age 25-34, and number 2 above heart disease for people age 55-64. COVID-19 ranked number 3 among people age 65 and older, above chronic lower respiratory disease for people age 65-74 and 75-84 years, and above Alzheimer disease for people age over 85 years.

Even among children age 1-14, COVID-19 was in the top 10 leading causes of death through August and September 2021. Among children age 5-14, COVID-19 ranked as the number 6 leading cause of death in August and September. Among children ages 1-4, COVID-19’s rank rose from number 13 to number 7 among leading causes of death in August 2021 and held there in September.

Over 90,000 COVID-19 deaths since June 2021 likely would have been prevented with vaccinations

COVID-19 vaccines that are free, safe, and highly effective have been widely available to all adults in the U.S. since early May 2021. Older and higher-risk adults in the U.S. had access to these vaccines months earlier. Therefore, by June 2021, adults in the U.S. generally could have been fully vaccinated and protected from most cases of severe illness or death due to COVID-19.

To estimate the number of COVID-19 deaths among adults that could have been prevented with vaccines, we looked at COVID-19 deaths among unvaccinated people in the months after vaccines were widely available (June through September 2021). We summed COVID-19 deaths in each month since June and subtracted COVID-19 deaths among children age 0-17 years. Then, we subtracted COVID-related deaths among vaccinated people with a breakthrough COVID-19 infection from total COVID-19 deaths among adults in each month. Even if all of the unvaccinated people who died of COVID-19 had chosen to get vaccinated, some of those deaths may not have been preventable since vaccines are not a 100% effective. A recent CDC study showed age-standardized vaccine effectiveness against deaths of 91% in the June 20–July 17 period and 94% in the April 4–June 19 period. Based on this study, we assume 91% of COVID-19 deaths among unvaccinated people likely would have been prevented with COVID-19 inoculations.

We find that since June 2021 over 90,000 lives likely would have been saved with vaccinations. Most of these preventable deaths occurred in the last month, well after vaccines became available. In September 2021 alone, approximately 49,000 deaths likely would have been averted if they had chosen to get vaccinated against COVID-19.

The overwhelming majority of COVID-19 hospitalizations and deaths continue to be preventable.


We used the KFF COVID-19 Tracker data for average daily and monthly total COVID-19 deaths in the United States. October 2021 average COVID-19 deaths from COVID-19 are averaged through October 7, 2021. For data on deaths due to other leading causes, we used monthly provisional counts of death by select causes, 2020-2021.  For other leading causes, we used CDC data for weekly counts of death by select underlying causes of death. For other leading causes from the weekly counts CDC file, only MMWR weeks 1-25 are included in average daily deaths for 2021. The average daily deaths for accidents and suicides are from 2020. Heart disease deaths were combined for all circulatory disease except stroke. Stroke represents cerebrovascular disease. In the second chart, respiratory disease represents chronic lower respiratory disease and the 2020 average daily deaths for accidents are reported.

For age-specific rank of COVID-19 deaths among other leading causes of death, we used CDC provisional COVID-19 deaths data by age for January – June 2021 (as of August 18, 2021) and CDC provisional death counts for other leading causes. Infants were excluded from this analysis as the 15th leading cause of death based on 2019 CDC Wonder data had a monthly average greater than the highest COVID-19 death count for this age group in any given month in 2021.  For age-specific leading causes for which 2021 monthly provisional death counts were not available, we used CDC Wonder data for 2019 for age-specific average monthly death counts.