Study: A mutant coronavirus has emerged, even more contagious than the original

The new strain appeared in February in Europe, migrated quickly to the East Coast of the United States and has been the dominant strain across the world since mid-March, the scientists wrote.

In addition to spreading faster, it may make people vulnerable to a second infection after a first bout with the disease, the report warned.

The 33-page report was posted Thursday on BioRxiv, a website that researchers use to share their work before it is peer reviewed, an effort to speed up collaborations with scientists working on COVID-19 vaccines or treatments. That research has been largely based on the genetic sequence of earlier strains and might not be effective against the new one.