The Delta variant (B.1.617.2, formerly India variant) of SARS-CoV-2 originated and rapidly spread in India, and is emerging in the United States, as well as in many other countries. On June 15, 2021, the CDC designated the Delta variant a variant of concern (VOC) in the United States.
Variants of SARS-CoV-2 continue to emerge. The Delta variant is highly transmissible. Data indicate that Delta is 40-60% more transmissible than Alpha and almost twice as transmissible as the original Wuhan strain of SARS-CoV-2.
The Delta variant of SARS-CoV-2 is highly transmissible; vaccination is the most important strategy to prevent severe illness and death. On July 27, CDC recommended that all persons, including those who are fully vaccinated, should wear masks in indoor public settings in areas where COVID-19 transmission is high or substantial.
The delta variant is characterized by the spike protein mutations T19R, Δ157-158, L452R, T478K, D614G, P681R, and D950N. Several of these mutations may affect immune responses directed toward the key antigenic regions of receptor binding protein (452 and 478) and deletion of part of the N-terminal domain.
P681R is at the S1–S2 cleavage site, and it appears that strains with mutations at that site may have increased replication, which leads to higher viral loads and increased transmission.
Symptoms of Delta tend to be a little different than other strains, but that does not necessarily mean the associated symptoms are more severe.
Delta variant Covid-19
