First reported in India late 2020, the SARS-CoV-2 Delta Variant is more than twice as infectious as the original virus and more potent among vulnerable, unvaccinated demographics including children. It comprises over 80% of the new infections within the US and has verifiably spread to 129 other countries according to the CDC.

Variants amongst viruses are expected – think of influenza and the yearly flu shot – constant mutations usually cause inconsequential differences in the genetic makeup of the original. However,  they occasionally hit upon an arbitrary correct sequence that allows it to be more contagious and more severe than other strains. Such mutations may aid the virus in penetrating the immune system more effectively or increasing the transmission rate.

One such strain that won the grotesque mutational lottery was the Alpha Variant. First reported in late 2020 in the UK, it is labelled as a Variant of Concern (VOC) alongside the Beta, Gamma, and Delta variants. Estimated to be 80-150% more infectious than the original strain, it overtook much of the UK’s cases throughout early 2021 according to YaleMedicine.

Delta’s mutations overlap with the Alpha variant in some places but uniquely contain mutations which affect the spike protein. The spike protein is the operating part of the virus which is attached to the membrane and binds to cells in the body allowing the virus to infect the host. In a preprint study by the Cambridge Institute of Infectious Disease, Delta was found to have an increased replication of S proteins, which factor heavily into what makes it more transmissible.

Preliminary studies done by Public Health Scotland also indicate that Delta may cause more severe illness than previous strains. Risk of hospitalization approximately doubled compared to the Alpha variant and was especially notable in those with present illness or medical conditions. This may be owed to mutations that allow Delta to more effectively evade the immune system, other variants including Alpha have also shown to contain such mutations according to the New England Journal of Medicine.

Vaccination still remains the single best way to protect people against infection. Even the variants of COVID are susceptible to vaccination. Most COVID vaccine developers focused on a relatively new style of mRNA vaccines. These vaccines inject mRNA code for the S protein into the muscle cells which then produces the protein. The body, recognizing it as foreign, produces the proper antibodies making it prepared for any coming infection, Pfizer and Moderna both use mRNA (over 90% effective in both).

There are conflicting anecdotes and studies on whether Delta leads to more breakthrough infections amongst vaccinated populations or not, with the latter being far more supported. For example, a study by the Public Health England validated the Pfizer-BioNTech to be 88% effective against symptomatic disease and 96% effective against hospitalizations for the Delta Variant.

Even though this recent surge in cases seems like a regression, the recent FDA clearing of the Pfizer-BioNTech vaccine will likely lead to an even greater uptick in vaccinations. Getting vaccinated and remaining diligent about proper sanitation will continue to be the foremost tools in combating this surge.