The Delta variant of the SARS-COV-2 virus is a version/mutation of the virus that causes COVID-19 in humans that happens to be significantly more transmissible than previous variants. This means that when the delta variant is introduced to a region, it will “take over” and become the predominant variety of SARS-COV-2 that is circulating. Because it is easier to transmit/catch, the number of cases also tends to go up in that region.

All of the following graphs are from the great covariants.org website. I encourage you to check it out and look at all of the country and state graphs.

For example, in the country of India, Delta (dark green in the graphs) was at 7% of all sequences in the March 8-22nd timeframe, and grew to 91% in the May 3-17th timeframe.

This pattern of Delta out-performing all other variants repeats in other countries and US states where it is introduced.

How does this apply to Florida specifically?

The Delta variant has been introduced to Florida, but as of June 14-28th, it is currently only found in 34% of sequences (Dark red is the Alpha variant currently at 40%). If patterns in other countries and US states continue in Florida, over the month of July, the Delta variant will expand it’s share of the “market” (humans to infect) until it is over 90%.

Most individuals don’t care which specific variant they are infected with, but from a population perspective, the Delta variant is significantly more transmissible, meaning that it will drive more infections. Combined with the elimination of non-pharmacological interventions (masking & social distancing) in Florida, we will see large numbers of infections in the un-vaccinated. (And even a few breakthrough infections in the vaccinated.)

Fortunately, current vaccines used in the US (Pfizer, Moderna, J&J) all do a good job protecting vaccinated individuals against the Delta variant. [It is possible a vaccinated individual can still catch and pass it on, but they are much less likely to develop severe life threatening symptoms.] Unfortunately, only 59% of the   population (12+ eligible for vaccination) have received at least one dose, leaving a good portion of the population (children under 12 and the un-vaccinated) susceptible.