The new study is the largest to date to suggest that a handful of cases popped up in the U.S. weeks before the virus was recognized by health officials.

More in category

Tokyo Olympics live updates: Women's 100m could be historic, USA baseball in action and Djokovic falls
July 31, 2021USA Today
Tokyo Olympics live updates: Women's 100m could be historic, USA baseball in action and Djokovic falls
Simone Biles withdrew from two individual gymnastics events
July 31, 2021CNN
Simone Biles withdrew from two individual gymnastics events
A third of eligible people aren't vaccinated. Here's what we know about them
July 28, 2021CNN
A third of eligible people aren't vaccinated. Here's what we know about them
Austin health officials warn there's only 16 ICU beds left in the region
July 30, 2021CBS
Austin health officials warn there's only 16 ICU beds left in the region
Lollapalooza sparks COVID worries as concertgoers flock to Chicago
July 30, 2021CBS
Lollapalooza sparks COVID worries as concertgoers flock to Chicago
CDC says
July 30, 2021CBS
CDC says "pivotal discovery" prompted new mask guidance
CDC says
July 30, 2021CBS
CDC says "the war has changed" in document about COVID vaccines
Ron Johnson Against Vaccine Mandate, Unless Disease Is 'Incredibly Deadly'
July 31, 2021Newsweek
Ron Johnson Against Vaccine Mandate, Unless Disease Is 'Incredibly Deadly'
Two Georgian judo athletes ejected from Olympics after going on Tokyo sightseeing trip
July 31, 2021USA Today
Two Georgian judo athletes ejected from Olympics after going on Tokyo sightseeing trip
Tokyo Olympics live updates: Women's 100m, Team USA baseball vs. Korea to close out Saturday; Novak Djokovic fails to medal
July 31, 2021USA Today
Tokyo Olympics live updates: Women's 100m, Team USA baseball vs. Korea to close out Saturday; Novak Djokovic fails to medal
The two largest wildfires in the US have burned land nearly the size of New York City, Los Angeles and Chicago combined
July 31, 2021CNN
The two largest wildfires in the US have burned land nearly the size of New York City, Los Angeles and Chicago combined
Simone Biles sparks nationwide conversation on mental health
July 31, 2021The Hill
Simone Biles sparks nationwide conversation on mental health
CDC Head: There Won't Be a Federal Vaccine Mandate, 'Understands Pushback'
July 30, 2021Newsweek
CDC Head: There Won't Be a Federal Vaccine Mandate, 'Understands Pushback'
Inmates are Dying in Connecticut's Prisons Due to Medical Negligence
July 31, 2021Newsweek
Inmates are Dying in Connecticut's Prisons Due to Medical Negligence
As COVID Concern Grows In Kansas, So Does Confusion Over Who Is In Charge
July 31, 2021NPR
As COVID Concern Grows In Kansas, So Does Confusion Over Who Is In Charge
UK, Grenada, Saudi Arabia: More countries open to fully vaccinated travelers
July 31, 2021CNN
UK, Grenada, Saudi Arabia: More countries open to fully vaccinated travelers
Five takeaways on the science behind CDC's latest mask guidance
July 31, 2021CNN
Five takeaways on the science behind CDC's latest mask guidance
Delta variant drives concerns of long-term care facility outbreaks
July 31, 2021MSNBC
Delta variant drives concerns of long-term care facility outbreaks
The unvaccinated Covid surge is only beginning, experts warn
July 31, 2021CNN
The unvaccinated Covid surge is only beginning, experts warn
COVID hospitalizations increasing in Alameda County
July 30, 2021KRON4
COVID hospitalizations increasing in Alameda County
Search resumes for missing runner in Pleasanton
July 30, 2021KRON4
Search resumes for missing runner in Pleasanton