C.D.C. Internal Report Calls Delta Variant as Contagious as Chickenpox

Infections in vaccinated Americans are rare, compared with those in unvaccinated people, the document said. But when they occur, vaccinated people may spread the virus just as easily.

A Group of Scientists Presses a Case Against the Lab Leak Theory of Covid

In a review of recent studies and comparisons to other outbreaks, a group of virologists contends that there is more evidence to support a natural spillover from animals to humans.

Opinion | Where Did the Coronavirus Come From? What We Already Know Is Troubling.

Even if the coronavirus did not emerge from a lab, the groundwork for a potential disaster had been laid for years, and learning its lessons is essential to preventing others.

A Top Virologist in China, at Center of a Pandemic Storm, Speaks Out

The virologist, Shi Zhengli, said in a rare interview that speculation about her lab in Wuhan was baseless. But China’s habitual secrecy makes her claims hard to validate.

A Top Virologist in China, at Center of a Pandemic Storm, Speaks Out

The virologist, Shi Zhengli, said in a rare interview that speculation about her lab in Wuhan was baseless. But China’s habitual secrecy makes her claims hard to validate.

The Latest Coronavirus Comes From Dogs

A newly identified coronavirus may not pose a serious threat, but the finding highlights the need to monitor animal viruses more proactively, scientists say.