A COVID-19 variant first identified in India is spreading well beyond and risking the relative comfort that has come with vaccine rollouts in the US. The Delta variant, B.1.617.2, is now the dominant strain in the UK, making up more than 60% of cases in some areas, reports NPR. "We cannot let that happen in the United States," where it accounts for more than 6% of cases, says Dr. Anthony Fauci. He noted the variant may bring more severe outcomes than the Alpha variant, B.1.1.7, first detected in the UK, per CNN. One epidemiologist says Delta may be 60% more transmissible than Alpha, per Reuters. The good news is vaccines appear to work against it. A study from Public Health England found the Pfizer vaccine was 88% effective against symptomatic disease from the Delta variant two weeks after the second dose, and 93% effective against Alpha.
Two doses of the AstraZeneca vaccine offered 60% effectiveness against Delta and 66% against Alpha. The bad news is the results are less promising after one dose. Both the Pfizer and AstraZeneca vaccines were 33% effective against symptomatic disease from the Delta variant three weeks after the first dose and 50% effective against the Alpha variant. That's why the Delta variant serves as "a powerful argument" to get vaccinated, says Fauci, who previously noted vaccines offer better protection than immunity from prior infection. Research shows variants aren't easily recognized by antibodies alone. But immunization against the original COVID-19 strain provides other immune responses, including the production of so-called "killer" T-cells, which help fight variants, writes Dr. Onyema Okolo, per Yahoo. (Read more COVID variants stories.)