ATLANTA - EXCLUSIVE: The Centers for Disease Control and Prevention on Tuesday will announce that the delta strain of COVID-19 is a "variant of concern" in the U.S., but that two doses of the Pfizer ...

Vaccine effectiveness against COVID-19 infection dropped from 91% to 66% once the delta variant accounted for the majority of circulating virus, according to a study published Tuesday by the U.S.

The more contagious Delta variant of Covid-19 now makes up 83% of sequenced samples in the United States, US Centers for Disease Control and Prevention Director Dr. Rochelle Walensky said Tuesday.

A growing number of public-health experts are urging the Centers for Disease Control and Prevention to recommend that even fully vaccinated people wear face masks in public amid the resurgence of ...

ATLANTA, Ga. — The delta variant that’s now the dominant strain of coronavirus in the U.S. appears to be as transmissible as chickenpox, according to an internal document from the Centers for Disease ...

Differing strains of the coronavirus continue to appear around the world and a new COVID-19 variant, the so-called "Delta" variant, has health experts concerned. The variant, otherwise known as B.1617 ...

A new study released Wednesday by the Centers for Disease Control and Prevention says people who suffered a previous COVID-19 infection were protected from another infection or hospitalization during ...

The delta coronavirus variant surging across the United States appears to cause more severe illness and spread as easily as chickenpox, according to an internal document from the US Centers for ...