At least seven strains of the new coronavirus have been circulating in California.
This is since the COVID-19 outbreak in the United States started, sources at UPI have revealed.
The findings suggest that the cases of the disease likely originated from several sources.
"While the sample size is small, this study suggests that there may have been multiple introductions of the virus into the United States," Brandon Brown, associate professor of social medicine population and public health at the University of California-Riverside
This includes overseas travelers and also visitors from other states, like Washington.