The COVID-19 Delta Variant: Here’s What We Know So Far

Updated July 9, 2021

Although the COVID-19vaccines arebeating back the virus, thelatest variant, ‘Delta,𲹻徱Բworldwideand could take aǷɱڳܱtoll onunvaccinated pDZܱپDzԲ,𳦾ydzܲԲadultsand underserved individuals,according to Dr. Roy M. Gulick, chief of the Division of Infectious Diseases at NewYork-Presbyterian/ձavɫƬ Medical Center and professor of medicine at ձavɫƬ. “Delta currently accounts for about 51% of U.S. COVID-19 cases and is the variant that is increasing the fastest throughout the country,” Dr. Gulick says.

Technically called B.1.617.2,Delta what the Centers for Disease Control (CDC) callsa,which means it is more transmissible and severe than other variants.“The Delta variant is about 50% to 60% more transmissible than the original virus,” Dr. Gulick says.

Currently,B.1.1.7orAlphathe mostprevalentvariantin the United States. ButDeltaisspreading fast.The CDC says ithas infected people in, andcomprises  of casesin India and Britain.Itcomprisedjust 0.1 percent ofcasesin the U.S.in early April, 9.5 percent by early June andapproximately20.6 percentnow,.“The Delta variant is spreading rapidly throughout the world. It is now the dominant viral strain in the United Kingdom and the U.S.,” Dr. Gulick says.

Even though there is no evidence that Delta is deadlier than other variants,its contagiousnessalone could let ittake a sizeable toll on unvaccinated pDZܱپDzԲ,especiallyadults aged 18–29 years,rural versus urbanresidents,or peoplewho are uninsured,impoverished,orlack access to a computerorInternet,

If you’re fully vaccinated--which means you’ve had two doses of the Pfizer-BioNTech orModernavaccines or one dose of the Johnson & Johnson vaccine--then you’re most likely protected against Delta. You’re far less protected, however, if you’re only half vaccinated.“Full vaccination with the mRNA vaccines (Pfizer and Moderna) protect well against the Delta variant and the other common variants. The Johnson & Johnson vaccine has not yet been tested, but likely also offers protection, though possibly at a lower rate,” Dr. Gulick says. Meanwhile, some studies haveevenfound thatcomplete vaccine regimens seem to besomewhat less effective at preventing infection from Deltathan other strains.

Either way, vaccination the best way to protect yourself and those you love,slow the spread ofCOVID-19,anddiscourage the emergence ofnew, morevirulentvariants.“Vaccines are the best tool we have to end the COVID-19 pandemic,” Dr. Gulick says. “People who can’t get vaccinated or don’t respond to vaccinations (for example, people with compromised immune systems) should continue to wear a mask, wash their hands, and practice social distancing.”

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