The Delta variant causes more infections and spreads faster than early forms of SARS-CoV-2, the virus that causes COVID-19.

The Delta variant is highly contagious, more than 2x as contagious as previous variants.

Some data suggest the Delta variant might cause more severe illness than previous variants in unvaccinated people.

In two different studies from Canada and Scotland, patients infected with the Delta variant were more likely to be hospitalized than patients infected with Alpha or the original virus that causes COVID-19. Even so, the vast majority of hospitalization and death caused by COVID-19 are in unvaccinated people.

1. Delta is more contagious than the other virus strains

The CDC has labeled Delta “a variant of concern” using a designation also given to the Alpha strain that first appeared in Great Britain, the Beta strain that first surfaced in South Africa, and the Gamma strain identified in Brazil. (The new naming conventions for the variants were established by the World Health Organization [WHO] as an alternative to numerical names.)

The Delta variant of the virus that causes Covid-19 is often described as highly transmissible. So, what does that actually mean?

Scientists studying Covid-19 say that Delta's increased contagiousness means we need to update our thinking about exposure risks. Because people infected with Delta carry higher levels of virus than with earlier strains, the old rules of thumb no longer apply, they say—including the conventional wisdom that it takes 15 minutes of close contact with someone to get infected.

The Delta variant, also known as B.1.617.2, can spread more easily, according. 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.

2.Unvaccinated people are at risk.

People who have not been fully vaccinated against COVID-19 are most at risk.Kids and young people are a concern as well. “A recent study from the United Kingdom showed that children and adults under 50 were 2.5 times more likely to become infected with Delta,” says Dr. Yildirim. And so far, no vaccine has been approved for children 5 to 12 in the U.S., although the U.S. and a number of other countries have either authorized vaccines for adolescents and young children or are considering them.

People who are not vaccinated against Covid-19 are two times more likely to be re-infected with deadly infectious disease, according to a study by US Center for Disease Control and Prevention (CDC)

"To reduce their likelihood for future infection, all eligible persons should be offered Covid-19 vaccine, even those with previous SARS-CoV-2 infection," it added.Although laboratory evidence suggests that antibody responses following Covid-19 vaccination provide better neutralisation of some circulating variants than does natural infection, few real-world epidemiologic studies exist to support the benefit of vaccination for previously infected persons, the CDC said.

Infectious disease experts say large-scale outbreaks among unvaccinated people are being fueled by the highly contagious Delta variant.

3.Delta could lead to 'hyperlocal outbreaks.'

If Delta continues to move fast enough to accelerate the pandemic,the biggest questions will be about the heightened transmissibility—how many people will get the Delta variant and how fast will it spread?

It lasted only a few seconds: One man walked past another man in a mall in Sydney.

When officials later watched CCTV footage of the encounter, they saw that this was the only interaction between the two. But it was enough for one of the men, who didn’t realize that he was infected with the delta variant of the coronavirus, to infect the other.

Whether someone gets sick from these exposures also depends on many variables, including the state of their own immune system, how long the infected person has been sick and their personal viral load, the ventilation in the space, and other factors.

Another worst-case scenario is a transmission documented in a Korean hospital where one person got sick after going into a shared bathroom 40 minutes after an infected person had used it.

But the publicly available government reports on the cases in Australia omit some important details, including whether the people were wearing masks (they likely were not, as they weren’t required to at the time) or whether the people who caught the virus were vaccinated (they likely were not, as Australia has been dealing with vaccine supply issues).

4. There is still more to learn about Delta.

One important question is whether the Delta strain will make you sicker than the original virus. But many scientists say they don’t know yet. Early information about the severity of Delta included a study from Scotland that showed the Delta variant was about twice as likely as Alpha to result in hospitalization in unvaccinated individuals, but other data has shown no significant difference.

5.Vaccination is the best protection against Delta.

The most important thing you can do to protect yourself from Delta is to get fully vaccinated, the doctors say.

Face masks can provide additional protection and the WHO has encouraged mask-wearing even among vaccinated people.

The CDC updated its guidance in July to recommend that both vaccinated and unvaccinated individuals wear masks in public indoor settings in areas of high transmission to help prevent Delta’s spread and to protect others,especially those who are immuno-compromised, unvaccinated, or at risk for severe disease. The agency is also recommending universal indoor masking for all teachers, staff, students, and visitors to K-12 schools.

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.