A public health expert says that fully vaccinated Americans are helping spread the Indian 'Delta' variant of the novel coronavirus across the country.
The variant, which is 50 percent more transmissible than the Alpha variant that originated in the UK, currently makes up more than half of cases in the U.S.
But because the Centers for Disease Control and Prevention (CDC) recommends that vaccinated people not get tested for COVID-19 unless they're symptomatic, it could mean that the true prevalence is much higher.
'We actually have states where hospitalizations are going up more than cases,' Dr Christopher Murray, the director of the Institute for Health Metrics and Evaluation at the University of Washington, told Insider.
'We're probably missing a bunch of transmission in vaccinated individuals...There's no doubt in my mind.'
It could explain why states with high vaccination rates such as California, Illinois, New York and Washington are seeing a rise in cases.
A public health expert says he believes the Indian 'Delta' coronavirus variant is partly being spread due to transmission from vaccinated Americans, even in highly vaccinated pockets of the country (above)
In Los Angeles, where 60% of residents aged 16 and older are fully vaccinated, COVID-19 infections have risen by 165% in a week (above)
In New York City, where 63% of all adults have completed their vaccine series, new cases have risen by 295 since June 24 (above)
According to CDC data updated on Tuesday evening, the Delta variant, also known as B.1.617.2, makes up 51.7 percent of all new infections.
That's up from the 26.1 percent of cases previously linked to the variant, meaning its prevalence has nearly doubled in two weeks.
The Delta variant has been detected in all 50 states and accounts for more than 80 percent of new infections in Midwestern states such as Iowa, Kansas and Missouri, where vaccination rates are lagging.
About half of all states have been seeing COVID-19 cases increase as the variant spreads, a DailyMail.com analysis of Johns Hopkins data earlier this week found.
But unvaccinated communities are not the only regions reporting increases in infections.
Los Angeles County, where 60
