The number of coronavirus deaths in the United States crossed 300,000 on Monday, as the hardest hit nation rolled out its first vaccine inoculations on Monday.

The staggering death toll comes as the nation begins a historic inoculation campaign using a vaccine developed by Pfizer Inc and BioNTech SE. Moderna Inc’s vaccine could get approval as soon as this week.

The vaccine comes as COVID-19 cases explode across the nation and hospital intensive care units run out of beds.

Daily coronavirus cases and deaths have set records multiple times since Thanksgiving holidays with daily fatalities topping 3,000 for the second time last week on Friday, the same day the vaccine got approval from the Food and Drug Administration.

It took 27 days to go from 250,000 total U.S. COVID-19 deaths to 300,000 – the fastest 50,000-death jump since the pandemic began. Some models project that deaths could reach 500,000 before vaccines become widely available in the spring and summer.

In recent weeks, South Dakota and North Dakota have led the nation in deaths per capita. Overall, New Jersey and New York, early epicenter of the US outbreak, lead the nation in per capita deaths.

The United States recently crossed 16 million confirmed cases – the most in the world.

According to Reuters analysis, the United States is reporting 91 deaths per 100,000 people, seventh worst in the world on a per capita basis and 2.5 times the rate in Canada.

The nation’s hospitals are flooding with COVID-19 patients, threatening to overwhelm healthcare systems and providers.

There are over 108,000 hospitalized COVID-19 patients, the highest since the first coronavirus case was detected in the country in January.