The total death rate in the U.S. spiked above the coronavirus death count in the early weeks of the pandemic, The Washington Post reported Monday.

An analysis of federal data conducted by a team headed by the Yale School of Public Health found that the U.S. recorded 15,400 excess deaths between March 1 through April 4, almost twice the number attributed to the coronavirus. In that time period, 8,128 coronavirus fatalities were reported.

Excess deaths measure the difference between the number of deaths expected to occur without the pandemic and the number of actual deaths recorded by the National Center for Health Statistics (NCHS). The center released data for the five weeks on Friday.

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The excess deaths do not automatically mean the fatalities were a result of the coronavirus, although some could have died because of the pandemic if they were hesitant to go to the hospital, the Post reported.

The higher than expected number of deaths helps scientists determine the overall impact of the coronavirus pandemic. It also shows the early reported numbers that were cited when states decided to shut down were likely to be incomplete.

New York City, which has been hit hard by the virus, recorded 6,300 excess deaths in the five-week period, while the city publicly reported 2,543 coronavirus deaths. Its neighbor New Jersey found there to be at least 2,100 excess deaths, while reporting 846 COVID-19 deaths.

Daniel Weinberger, the leader of the research team, told the Post the analysis shows the death toll is significantly higher than what was reported.

Undercounting during a pandemic is not rare, and many countries around the world are struggling to keep their numbers accurate and up to date, the Post noted. Experts say America’s data may be incomplete because of reporting lags and since the initial death counts in almost every state only included those who tested positive for coronavirus.

The U.S. has documented almost 55,000 deaths from the coronavirus, according to data from Johns Hopkins University.