The extraordinarily transmissible Delta variant of the coronavirus, which overtook all different variants in the USA only a few months in the past, now represents greater than 99 p.c of circumstances tracked within the nation, based on the information from the Facilities for Illness Management and Prevention.
The variant brought on caseloads to surge in Britain and India this spring and summer time, and in each international locations outbreaks resurfaced after circumstances had gave the impression to be on the decline. The Delta variant has been fueling outbreaks in the USA all through the summer time, its contagiousness benefiting from the quantity of people that have resist Covid vaccinations.
The information on Delta’s prevalence, contained within the C.D.C.’s newest biweekly report of virus sequencing, exhibits it climbing from simply over 1 / 4 of circumstances in mid-June to close complete dominance in September.
“It’s not sudden, as a result of it’s extra transmissible, however it’s also a robust reminder that we have to have steady vigilance,” mentioned Dr. Saskia Popescu, an epidemiologist and assistant professor at George Mason College.
The C.D.C.’s COVID Data Tracker, reporting results for the two-week period ending on Sept. 11, put the B.1.617.2 lineage of Delta at 99.4 percent among variants of concern, with two other Delta lineages tracked at 0.2 percent and 0.1 percent, the Mu variant — first detected in January in Colombia — at 0.1 percent and several other, unidentified variants at 0.2 percent. That data is based on thousands of sequences provided every week through the C.D.C.’s national genomic surveillance efforts, according to the agency’s website.
The country recently experienced a rise in hospitalizations, despite the availability of highly protective vaccines, and the Delta variant has been cited as the cause.
“We’re seeing more children in the hospital now because the Delta variant is more readily transmissible among everybody, adults and children,” Dr. Anthony S. Fauci, the nation’s top infectious disease doctor, told The New York Times on Sept. 9.
Dr. Popescu said the rise of Delta should help Americans and health officials realize the coronavirus remains a serious public health threat.
“The biggest piece is, ‘Don’t let your guard down.’ We need continuous surveillance, genomic sequencing, access to testing and public health interventions,” Dr. Popescu said.
Vaccination and wearing masks can help, she said.
“We have transmission occurring with very limited exposure, and that means that, for example, times without a mask, when you are out and around others, become much more of a risk,” Dr. Popescu said.