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Delta variant now dominant COVID strain in the U.S.

The Delta variant now accounts for over half of COVID-19 cases in the United States. Photo/Web MD.

Mary Beth Sallee

Jobe Publishing, Inc.


Although it seems like things are getting back to normal as restrictions lift and states reopen, COVID is continuing to remind everyone that the pandemic is not quite over.

The Delta variant, a highly contagious form of COVID-19, has spread quickly and is now accounting for over half of the coronavirus cases within the United States.

As of July 8, Kentucky had 26 confirmed cases of the Delta variant, including 5 cases in fully-vaccinated individuals. However, Governor Andy Beshear stated during a press conference that that number is likely higher than realized. The number of new COVID-19 cases in Kentucky, as well as the statewide positivity rate, are again on the rise.

Just as flu can have variants, so can COVID-19. According to the Center for Disease Control and Prevention (CDC), genetic variants of SARS-CoV-2, the virus that causes COVID-19, have been emerging and circulating around the world throughout the entirety of the pandemic.

The Alpha variant, or B.1.1.7 variant, which was first identified in the U.K. and was the dominant U.S. strain in April, now makes up 28.7% of COVID-19 cases in the U.S.

The Delta variant, also known as B.1.617.2, was first detected in India. It represented just 10% of COVID-19 cases in the U.S. about a month ago and around 30% of cases between June 6 and June 19.

According to CDC estimates from the two week period between June 20 and July 3, the Delta variant now accounts for 51.7% of COVID-19 cases across the U.S.

The CDC monitors 10 regions across the nation. In one of those regions that covers Iowa, Kansas, Missouri, and Nebraska, the Delta variant already accounts for 80.7% of cases in that particular region. In a second region, which covers Colorado, Montana, North Dakota, South Dakota, Utah and Wyoming, the Delta variant accounts for 74.3% of cases.

To put the Delta variant’s contagiousness into perspective, the Alpa variant of COVID-19 was already 50% more contagious than the original COVID-19 strain first detected in Wuhan, China.

The Delta variant, however, is between 40% to 60% more contagious than the Alpha variant and is twice as likely to lead to hospitalization.

Although previous reports have stated that COVID-19 vaccines from Biotech firms Moderna and Pfizer are highly effective against the most recent strains of COVID-19, the Delta variant has caused a surge in cases even in highly vaccinated countries. Those highly vaccinated countries, like Israel, have either prolonged or reintroduced restrictions to combat the rapid spread of the Delta variant.

According to data from Israel’s health ministry, studies have proven that Pfizer’s COVID-19 vaccine is significantly less effective at preventing infection with the Delta variant than previous strains of the coronavirus. The study suggests that a full course of the Pfizer vaccine is 64% effective at preventing symptomatic COVID-19, much lower than previous estimates of 90% or more.

Other data is showing that the Pfizer vaccine still appears to be highly effective at 93%, although this is lower than earlier studies suggested and lower for other variants such as the Delta variant. Pfizer, however, has recently announced that it will be seeking U.S. authorization for a third dose of its COVID-19 vaccine. The company stated that a booster shot within 12 months could increase immunity and perhaps provide additional support against the most recent variants of the disease.

The Moderna vaccine, which is based on the same type of technology as the Pfizer vaccine , said its vaccine remains effective against the Delta variant. Janssen Pharmaceuticals, the company responsible for the one-shot Johnson & Johnson vaccine, stated that its vaccine is also effective against the variant.

Data from the U.K. indicates that high vaccination rates are proving the difference between severe symptoms and death. This has prompted the U.K. government to make the controversial decision to end nearly all social restrictions on July 19, despite the country having one of highest rates of new cases across the world.

Overall, the research of how effective vaccines are against the Delta variant is incomplete due to the speed at which the variant has spread.

The symptoms of an infection caused by the Delta variant more closely resemble a common cold including a runny nose, a sore throat, and a headache. making it easier for people to unknowingly transmit the virus.

With the Delta variant causing increased infections among unvaccinated individuals, particularly in children and young individuals, the World Health Organization (WHO) has advised vaccinated Americans to still wear masks. However, the CDC has so far declined to follow the WHO’s advice on this matter, and the White House has already released a statement that decisions on new pandemic restrictions will be left up to individual states.

For more information about the Delta variant, visit the CDC website at

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