A controversial guideline saying people without Covid-19 symptoms didn’t need to get tested for the virus came from H.H.S. officials and skipped the C.D.C.’s scientific review process.
An unexpected upswing in positive tests at the University of Illinois at Urbana-Champaign showed how even the most comprehensive approaches to limiting the virus’s spread can break down.
The buzzy idea is impractical, critics said. And there isn’t yet real-world data to show it will work.
Most antibody tests are useful only for large population surveys, diagnosis in certain children or when initial diagnostic testing fails, according to an expert panel.
The new policy states that so-called laboratory-developed tests will no longer require F.D.A. authorization.
As the coronavirus spread on the Fort Apache reservation in Arizona, medical teams sought out residents who might have been exposed. The effort paid off in unexpected ways.
Many medical experts — including members of his own staff — worry about whether Dr. Hahn has the fortitude and political savvy to protect the scientific integrity of the F.D.A. from Mr. Trump.
Researchers in South Korea found that roughly 30 percent of those infected never develop symptoms yet probably spread the virus.
Experts are revising their views on the best methods to detect infections, setting aside long-held standards so that the spread of the virus can be more quickly tracked and contained.
Tuberculosis kills 1.5 million people each year. Lockdowns and supply-chain disruptions threaten progress against the disease as well as H.I.V. and malaria.