Key takeaways from the fourth week of the Elizabeth Holmes trial.

A Theranos lab director emerged as key prosecution witness during testimony focused on problems with the company’s blood tests.

Opinion | Rapid Tests Are the Answer to Living With Covid-19

Americans need both vaccines and universal access to rapid tests to get back to more normalcy.

She Was Training for a Marathon. Suddenly, She Could Barely Walk.

What could cause so sudden a decline?

How Accurate Are At-Home Covid Tests?

When used correctly, many at-home rapid tests are good at detecting people carrying high levels of the virus.

This Lab Charges $380 for a Covid Test. Is That What Congress Had in Mind?

Insurers say it’s price-gouging, but a law left an opening for some labs to charge any price they wished.

This Lab Charges $380 for a Covid Test. Is That What Congress Had in Mind?

Insurers say it’s price-gouging, but a law left an opening for some labs to charge any price they wished.

‘I Need an Army’: Across America, Schools Cram for Their Covid Tests

Some districts have established robust virus testing programs, but many others are struggling.

‘I Need an Army’: Across America, Schools Cram for Their Covid Tests

Some districts have established robust virus testing programs, but many others are struggling.

A ‘Race-Free’ Approach to Diagnosing Kidney Disease

The most common method of assessing the condition may make Black patients seem less ill than they really are, some experts say. A new report calls for scrapping the formula.

James Mattis, a Theranos board member, ‘didn’t know what to believe,’ he says in Elizabeth Holmes trial.

Mr. Mattis, the former defense secretary, testified that board

The United States v. Elizabeth Holmes

The trial of the Theranos founder throws a spotlight on tech stardom, start-up culture and Silicon Valley hubris.

Berlin Clubs Return With a Vengeance

A discothèque successfully sued the city over its ban on indoor dancing, and clubs have reopened. But if there’s a spike in coronavirus cases, the local government has explored a backup plan.

New Mandate Raises Question: Who’ll Pay for All the Covid Tests?

The Biden administration announces a rule that workers at large companies must get vaccinations or submit to regular testing.

The Pandemic Has Set Back the Fight Against H.I.V., TB and Malaria

Prevention and treatment fell in poor countries last year as access to health care declined, according to a new report.

In Silicon Valley, Criminal Prosecutors See No Evil

The Elizabeth Holmes fraud trial is set to be a major spectacle, but tech executives generally get a pass when it comes to wrongdoing.

Covid Medical Bills Are About to Get Bigger

As some insurers focus on encouraging vaccination, temporary waivers that kept patient costs low are expiring.

Schemer or Naïf? Elizabeth Holmes Is Going to Trial.

The trial for the founder of Theranos, the once high-flying blood testing start-up, will cap a saga of Silicon Valley hubris, ambition and deception.

N.Y.C.’s Challenge: Keeping 1 Million Students Safe Amid Delta

Mayor Bill de Blasio announced the school safety reopening plan on Thursday, raising questions about the city’s readiness to bring back all its students to schools next month.

He Passed Out Three Times in 10 Days. What Was Wrong?

Could all this really be a result of a urinary-tract infection?

They Still Live in the Shadow of Theranos’s Elizabeth Holmes

Female entrepreneurs said they were constantly compared to Ms. Holmes, the disgraced founder of Theranos, who faces trial soon.