The Delta variant and Covid-19 vaccines: what you need to know

the Delta variant of Covid-19 virus, the dominant strain in the United States, increases the cases in particular where vaccination rates are lower.

Also known as B.1.617.2, the variant was first identified in India in late 2020. It has spread to at least 85 countries, according to the World Health Organization, and has it- even mutated to produce another version which is causing concern in India.

Vaccines from Moderna Inc., Johnson & Johnson and Pfizer Inc. and its partner BioNTech SE – the three injections authorized in the United States – have been tested primarily in large clinical trials for their effectiveness in preventing symptomatic disease, rather than their ability to completely prevent infection. While vaccines appear to be slightly less effective in preventing symptomatic Covid-19 from the Delta variant, research has shown that they remain very effective in preventing serious illness and hospitalizations.

Overall, the share of eligible Americans fully vaccinated against Covid-19 has been stuck for weeks at about 57%.

Here’s what we know so far about the Delta variant and the vaccines.