• Covid-19 was the third leading cause of death in the U.S. in 2020, behind heart disease and cancer, according to a new CDC study.
• More than 3.3 million deaths were reported in the U.S. last year, a 16% increase over 2019.
• The deadliest weeks of 2020 were at the beginning of the pandemic in April and then in the middle of the holiday surge in late December.

The coronavirus was the third leading cause of death in the U.S. in 2020, behind heart disease and cancer, according to a new study from the U.S. Centers for Disease Control and Prevention.

More than 3.3 million deaths were reported in the U.S. last year, a 16% increase over 2019, according to provisional data published Wednesday compiled by the National Vital Statistics System, which examines and reports annual mortality statistics based on death certificates.

The deadliest weeks last year were at the beginning of the pandemic and then in the middle of the holiday surge, during the weeks ending April 11, with 78,917 fatalities, and Dec. 26, when 80,656 people died, the CDC found.

According to the study released Wednesday, Covid-19 was listed as the underlying cause for 345,323 deaths, killing more Americans than unintentional injuries, strokes, chronic lower respiratory disease, Alzheimer's disease, diabetes, influenza and pneumonia and kidney disease.

The agency's early findings were published months ahead of schedule due to "improvements in timeliness and the pressing need for updated, quality data during the global COVID-19 pandemic," researchers wrote.

Only heart disease and cancer killed more people in the U.S. than Covid-19 in 2020 — heart disease killed 690,882 people and cancer killed 598,932.

Covid-19 replaced suicide among the top 10 leading causes of death in the U.S., the study found. Overall, the annual death rate increased by nearly 16% in 2020 compared with a year earlier, the first time it's grown since 2017, the CDC said.

The highest annual death rates were reported among men, people ages 85 and older, and people who are non-Hispanic Black and American Indian and Alaskan Native, the CDC said.

However, when looking at Covid-19 alone, Hispanic and American Indian and Alaskan Native people, as well as those ages 85 and older, died from the disease at higher rates compared with every other group. Men died from Covid-19 at a higher rate than women.

CDC Director Dr. Rochelle Walensky said following the study's release that the findings should serve "as a catalyst" for Americans to drive down the spread of the virus and get vaccinated once it's their turn.

"I know this is not easy and so many of us are frustrated with the disruption this pandemic has had on our everyday lives, but we can do this as a nation working together," Walensky said during a White House Covid-19 press briefing Wednesday.

It typically takes researchers 11 months after the end of the calendar year to investigate "certain causes of death and to process and review data." While the daily total Covid death figures reported by the CDC are timely, they can underestimate the actual number of deaths because of "incomplete or delayed reporting."

"Provisional death estimates provide an early indication of shifts in mortality trends and can guide public health policies and interventions aimed at reducing numbers of deaths that are directly or indirectly associated with the COVID-19 pandemic," researchers wrote.

Some have tried to sow doubt about the true amount of deaths caused by Covid-19, claiming they may have been overstated. However, in a separate CDC study published Wednesday, the agency found that the death certificates accurately reflected the number of reported coronavirus fatalities.

The agency examined death certificates listing Covid-19 and at least one other co-occurring condition. The CDC found that in 97% of the deaths, Covid-19 was reported alongside another condition that was possibly caused by the virus, such as pneumonia or respiratory failure, or significantly contributed to its severity, such as diabetes or hypertension.

A small proportion of them — 2.5% of the certificates — documented conditions that aren't currently associated with Covid-19, the CDC found.

"These findings support the accuracy of COVID-19 mortality surveillance in the United States using official death certificates," the researchers said.