This story was updated July 21, 2021. 

July 12, 2021 -- As the COVID-19 pandemic continues across the world, public health officials are watching certain coronavirus mutations and variants that may be more contagious or deadly than the original strain. Viruses constantly change to adapt and survive, and variants emerge when a strain has one or more mutations that differ from others.

The CDC and World Health Organization (WHO) monitor these variations to find out if transmission could lead to a surge in COVID-19 cases and deaths, as well as whether current vaccines can provide protection. The U.S. classifies them as either a “variant of interest,” which may lead to outbreaks but isn’t widespread in the country; a “variant of concern,” which shows evidence of increased transmission and more severe disease; or a “variant of high consequence,” which makes vaccines and treatments much less likely to work well.

So far, the U.S. hasn’t classified any coronavirus variants as “high consequence,” but numerous strains have been labeled as “variants of concern” that need to be followed closely. In particular, the Delta variant has drawn focused attention during the past month due a rapid increase in COVID-19 cases in several countries, including the U.S.

Here’s what you need to know about the Delta variant:

What is the Delta variant?

The Delta variant, also known as B.1.617.2, can spread more easily, according to the CDC. The strain has mutations on the spike protein that make it easier for it to infect human cells. That means people may be more contagious if they contract the virus and more easily spread it to others. It is now the dominant strain in the U.S.

In fact, researchers have said that the Delta variant is about 50% more contagious than the Alpha variant, which was first identified in the U.K., according to The Washington Post. Alpha, also known as B.1.1.7, was already 50% more contagious than the original coronavirus first identified in China in 2019.

Public health experts estimate that the average person who gets infected with Delta spreads it to three or four other people, as compared with one or two other people through the original coronavirus strain, according to Yale Medicine. The Delta variant may also be able to escape protection from vaccines and some COVID-19 treatments, though studies are still ongoing.

What is the Delta Plus variant?

The Delta Plus variant, also known as B.1.617.2.1 or AY.1, is considered a “subvariant” of the Delta version, according to CBS News. It has a mutation that allows the virus to better attack lung cells and potentially escape vaccines.

First identified in India, Delta Plus has now been found in the U.S., U.K., and nearly a dozen other countries. India has labeled it a variant of concern, but the CDC and WHO haven’t.

Where did the Delta variant come from?

The Delta variant was first identified in India in December 2020 and led to major outbreaks in the country. It then spread rapidly and is now reported in 104 countries, according to a CDC tracker.

As of early July, Delta has become the dominant form of the coronavirus in the U.S., U.K., Germany, and other countries. In the U.K., for instance, the Delta variant now makes up more than 97% of new COVID-19 cases, according to Public Health England.

What are the symptoms of the Delta variant?

The symptoms are similar to those seen with the original coronavirus strain and other variants, including a persistent cough, headache, fever, and sore throat.

At the same time, COVID-19 patients in the U.K. have reported that some symptoms are slightly different for Delta, according to data from the ZOE COVID Symptom Study. Cough and loss of smell seem to be less common. Headache, sore throat, runny nose, and fever seem to be more common.

Is the Delta variant more deadly?

Scientists are still tracking the data to determine how deadly it is. Based on hospitalizations in the U.K., the Delta variant does seem to be more likely to lead to hospitalization and death, particularly among unvaccinated people, according to a recent study published in The Lancet.

What does the Delta variant mean for the unvaccinated?

People who haven’t been fully vaccinated against COVID-19 are most at risk, Yale Medicine reported. In the U.S., communities with low vaccination rates have seen a jump in cases, particularly in Midwest and Southern states such as Missouri and Arkansas. Outbreaks have also been found in Mountain states, such as Wyoming.

Kids and younger adults who haven’t been vaccinated may be susceptible as well. In the U.K., children and unvaccinated adults under age 50 were 2.5 times more likely to become infected with Delta, according to a recent study published by Imperial College London.

What does the Delta variant mean for the vaccinated?

Scientists are looking at how the Delta variant can cause breakthrough cases, or infections among people who are fully vaccinated. So far, they seem to be rare.

In a preliminary analysis, two doses of the Pfizer or Moderna vaccine appeared to be about 88% effective against disease and 96% effective against hospitalization with the Delta variant, according to Public Health England. The AstraZeneca vaccine, which has not been authorized for use in the U.S., was about 60% effective against disease and 93% effective against hospitalization.

Johnson & Johnson has also reported efficacy from its one-shot vaccine against the Delta variant, which researchers estimate to be similar to the AstraZeneca results. However, a study released July 19 on a preprint server – meaning it has not been peer reviewed – found the Johnson & Johnson vaccine’s protection decreased significantly over time, hinting that people who get the J&J shot may need a booster shot.

Now vaccine makers are testing booster shots to find out if they can better protect against the Delta variant and other variants that emerge in coming months. Pfizer announced that it will seek FDA authorization for a booster dose in August, according to CNN.

What is the Delta variant situation in the U.S.?

The Delta variant is present in all 50 states and now accounts for 52% of new infections in the U.S., The Washington Post reported. In Iowa, Kansas, Missouri, and Nebraska, it makes up about 80% of new cases.

Public health officials aren’t yet sure how the Delta variant will ultimately affect the U.S., though it has led to more cases across the world, according to NBC News. Lockdowns and curfews have been put in place in Australia, Bangladesh, and South Africa, and new travel restrictions were set in Germany, Hong Kong, and Taiwan to reduce the number of flights from countries with widespread transmission.

What is the Epsilon variant?

The Epsilon variant, also known as B.1.427/B.1.429, was first detected in Southern California. Lab studies suggest that Epsilon has three mutations in the spike protein that may make COVID-19 treatments and vaccines less effective, according to a recent study published in Science. It has now been reported in more than 30 countries.

Epsilon has about 20% higher transmission, according to the CDC. It was downgraded from a “variant of concern” to a “variant of interest” on June 29 due to a decrease in cases across the U.S. and data that showed vaccines are effective.

What is the Lambda variant?

The Lambda variant, also known as C.37, was first identified in Peru in August 2020. It has spread throughout South America, and the WHO designated it a “variant of interest” in mid-June.

Lambda has several mutations that are similar to other contagious variants, The New York Times reported, but scientists aren’t yet sure how risky it is. The variant accounts for less than 1% of cases in the U.S.

Show Sources

CDC: “SARS-CoV-2 Variant Classifications and Definitions: Variant of Interest,” “SARS-CoV-2 Variant Classifications and Definitions: Variant of Concern,” “SARS-CoV-2 Variant Classifications and Definitions: Variant of High Consequence,” “Selected Characteristics of SARS-CoV-2 Variants of Concern: B.1.617.2,” “COVID Data Tracker: Global Variants Report,” “Selected Characteristics of SARS-CoV-2 Variants of Interest: B.1.427.”

The Washington Post: “What you need to know about the highly contagious delta variant.”

Yale Medicine: “5 Things To Know About the Delta Variant.”

CBS News: “Delta Plus: As U.S. grapples with Delta variant, India raises alarm over a new COVID strain mutated from it.”

Public Health England: “SARS-CoV-2 variants of concern and variants under investigation in England, July 9, 2021,” “Vaccines highly effective against hospitalisation from Delta variant.”

ZOE COVID Symptom Study: “What are the new top 5 COVID symptoms?”

The Lancet: “SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness.”

Imperial College London: “REACT-1 round 12 report: Resurgence of SARS-CoV-2 infections in England associated with increased frequency of the Delta variant.”

CNN: “Pfizer says it’s time for a Covid booster; FDA and CDC say not so fast.”

NBC News: “The delta variant: Everything you need to know.”

Science: “SARS-CoV-2 immune evasion by the B.1.427/B.1.429 variant of concern.”

The New York Times: “Covid’s Lambda Variant: Worth Watching, but No Cause for Alarm.”

© 2021 WebMD, LLC. All rights reserved. View privacy policy and trust info