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 ...

The delta variant is fueling the COVID-19 surge in the United States, but experts warn that a more dangerous variant could emerge if more Americans don't get vaccinated. Delta is the most recent of ...

NEW YORK, N.Y. — Pfizer announced Wednesday that data shows a third dose of its COVID-19 vaccine can “strongly” boost protection against the highly transmissible delta variant. The pharmaceutical and ...

Here’s what the Centers for Disease Control and Prevention (CDC) says about the Delta variant, its symptoms, characteristics and other things to watch for: Viruses constantly change through mutation, ...

LAS VEGAS, NEVADA -- A California couple says they were fully vaccinated, but still contracted COVID-19 while on vacation as experts say breakthrough cases are possible, especially with the delta ...

LONDON — A newly-discovered mutation of the delta variant is being investigated in the U.K. amid worries that it could make the virus even more transmissible and undermine Covid-19 vaccines further.

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 ...

The CDC says 83% of all new COVID-19 cases in the U.S. can be attributed to the Delta variant. CBS News' Skyler Henry has more on the sharp increase in cases across the country. Then Dr. Amesh Adalja, ...