Audrey Carlsen

Ever since the coronavirus reached the U.S., officials and citizens alike have gauged the severity of the spread by tracking one measure in particular: How many new cases are confirmed through testing each day. However, it has been clear all along that this number is an understatement because of testing shortfalls.

Now a research team at Columbia University has built a mathematical model that gives a much more complete — and scary — picture of how much virus is circulating in our communities.

Updated October 21, 2021 at 9:16 AM ET

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Vaccinating a high percentage of the population against COVID-19 is a crucial part of the U.S. strategy to curb the pandemic.

Since COVID-19 vaccine distribution began in the United States on Dec. 14, more than 410 million doses have been administered, fully vaccinating over 189 million people or 57.1% of the total U.S. population.

President Trump has become the only president in U.S. history to be impeached twice.

The Democratic-led U.S. House of Representatives delivered the historic rebuke to Trump on Wednesday afternoon — exactly one week after his supporters stormed the U.S. Capitol building in a rampage that led to five deaths, including that of a Capitol Police officer.

The Democratic-controlled House approved a resolution Tuesday night calling on Vice President Pence to invoke the 25th Amendment of the Constitution to assume the powers of the presidency.

Updated May 28, 2021 at 2:50 PM ET

The U.S. Senate continues to take up President Biden's nominees for key roles.

The top figures in an administration are made up of a combination of Cabinet and high-ranking nominees who require Senate confirmation, and senior advisers tapped by the president, who don't require congressional approval.

Wildfires near cities have become commonplace in the Western United States, but this year the reach and intensity of the dangerous air pollution they produce has been the worst on record.

Many Americans in populous, urban areas endured smoke for longer than previous years. Some places experienced very unhealthy or hazardous air from wildfires for the first time ever recorded.

As COVID-19 continues to spread across the country, state and local health officials rush to try to detect and contain outbreaks before they get out of control. A key to that is testing, and despite a slow start, testing has increased around the country.

But it's still not always easy to get a test. While many things can affect access to testing, location is an important starting point.

Updated September 22, 2021 at 10:50 AM ET

This summer, Congress saw a months-long streak with no coronavirus cases among its members come to a halt, amid a national surge driven by the delta variant.

That streak was broken in July. That month, Republican Reps. Vern Buchanan of Florida and Clay Higgins of Louisiana reported infections. Buchanan says he was fully vaccinated, but that was less clear for Higgins.