Coronavirus: why could the US be the next country hit with the delta variant?

The United States is has administered more doses of covid-19 vaccines than any other country in the world. However, this does not mean all are immune.

The US is averaging around 13,997 confirmed cases a day, and more than 12,000 people remain hospitalized. Another threat looming is the emergence of variants, coupled with high vaccine hesitancy among some demographic groups.

What is a variant of concern?

To better distinguish between variants of the virus that pose a greater risk to the public, the Centers for Disease Control and Prevention (CDC) has described some strains as variants of concern. The organization defines a variant of concern as one where “there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), a significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures." 

The CDC has categorized the delta variant (B.1.617.2) as a “variant of concern” along with “B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.427 (Epsilon), and B.1.429 (Epsilon).”

Why is the CDC concerned about the delta variant?

This specific strain of the virus contributed to the unprecedented spread, hospitalization, and death in India earlier this year. Scientists believe that the delta variant poses an increased threat to the public as it can be transmitted more easily, and some monoclonal antibody treatments and vaccines may be less effective in treating or preventing the disease.

Currently, the dominant strain in the US is the alpha variant which originated in the United Kingdom. The alpha variant has shown that it is about 20% more transmissible compared to previous strains. On Tuesday, 22 June, Dr. Anthony Fauci highlighted recent reports that show the delta variant may be as much as 60% more transmissible. In his comments, Dr. Facui also stated that the variant "is currently the greatest threat in the U.S. to our attempt to eliminate Covid-19."

In early June, the alpha variant formed around sixty percent of total infections. However, what concerns scientists is how the delta strain is quickly forming a larger percent of infections. Dr. Fauci told reporters that the spread of delta is increasing "with a doubling time of about two weeks if you look from the May 8th with 1.2, to 2.7, to 9.9, and as of a couple of days ago, 20.6 percent." 

In April and May, the CDC estimated that it formed between 1.5 to 3 percent of infections, by early June, this figure increased to anywhere between 6.5 and 13 percent.

The CDC has also published information showing that the specific variant is most prevalent in two regions:

At the rate the variant is growing, some public experts worry that it could become the dominant strain of infection. Further concerns are driven by some indicators that the delta variant is more resistant to treatments and vaccines, meaning it could take the US more time to see the pandemic come to an end.

Additionally, with high levels of the population not yet vaccinated, the US could be increasingly impacted by the spread of the delta variant, which is more easily transmitted.