Delta variant: 5 things to know about the dominant strain of COVID-19 in the US

A variant of the COVID-19 virus has become the dominant version of the infection in the United States and is outpacing the original virus in much of the world.

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The Delta variant — so named by the World Health Organization which has chosen to name coronavirus variants after Greek letters — has been identified by the Centers for Disease Control and Prevention as the dominant strain of COVID-19 in the United States.

According to modeling by the CDC, the Delta variant became dominant in the country during the two weeks that ended July 3. During that period, 51.7% of the reported cases in the US were linked to the variant, first identified in India.

According to the WHO, the variant has been reported in 104 countries.

What is a variant? How is the Delta variant different from the original COVID-19 infection? Here is what we know about the new strain of the virus.

1. What is a variant of a virus?

A variant is a version of a virus that exists because the virus is constantly mutating, or changing, to adapt to its host. The Delta variant is a version of the COVID-19 virus that has changed in order to survive, something viruses do all the time.

2. How is the Delta variant different from the COVID-19 virus?

Experts say the Delta variant is different from the original COVID-19 virus because it is more contagious due to the fact it has become better at attaching itself onto cells in our bodies.

Monica Gandhi, an infectious disease expert at the University of California at San Francisco, told The Washington Post the Delta variant is “the one that is most likely to latch onto cells in a host, and it attacks that host better than the other variants because it can replicate itself better.”

The symptoms of the Delta variant may also be different. Doctors say they are seeing symptoms that are more cold-like with the Delta variant, such as runny nose, sore throat and headaches.

With COVID-19, the predominant symptoms reported were loss of taste and smell, shortness of breath, fever and a cough that would not let up.

3. Is the Delta variant more dangerous than the original virus?

While the Delta variant appears to be more transmissible, there is not enough evidence to say that the variant is more deadly, according to some scientists.

According to the Post, Public Health England and researchers in Scotland suggest that the variant may be associated with a higher risk of hospitalization.

Hospitals serving areas where the Delta variant is gaining a foothold have reported admitting more young and middle-aged COVID patients, the Post reported. That could be because fewer people in that age group have been fully vaccinated, health officials said.

According to The Wall Street Journal, health officials in Wyoming were able to see the difference in those who had COVID-19 during the height of the pandemic and those who have come in recently with the Delta variant.

According to Sodienye Tetenta, a critical-care physician at the Cheyenne Regional Medical Center, younger patients started coming in about two months ago with symptoms of COVID-19 that progressed from mild illness to respiratory distress more quickly than patients treated earlier in the pandemic.

“We could see that this was not the COVID of last year,” Dr. Tetenta said.

4. Will the vaccines protect against the Delta variant?

According to The Wall Street Journal story about the Wyoming hospital’s experiences with the Delta variant, the majority of those who contracted the version of COVID and suffered more debilitating symptoms were unvaccinated.

CDC Director Rochelle Walensky added to the conversation about vaccinations and the Delta variant when she suggested in a July 1 briefing that the variant may be to blame for a sharp increase in hospitalizations in areas of the country that have low COVID-19 vaccination rates.

The vaccines currently being used in the U.S. — Moderna, Pfizer and Johnson & Johnson — appear to work well against the variant, according to the CDC.

What researchers say they are seeing is a strong response from the vaccines against the Delta variant, and, more importantly, an ability to prevent severe sickness and deadly outcomes for people who have contracted the virus.

Researchers in England studied how effective the two-dose AstraZeneca and Pfizer-BioNTech vaccines were against the Delta variant, finding good protection from both vaccines.

Two doses of the Pfizer-BioNTech vaccine had an effectiveness of 88% in protecting against symptomatic disease from the Delta variant, according to the British study.

A similar study released in June out of Scotland found that the Pfizer vaccine was 79% effective against the variant.

Last weekend, a team of researchers in Canada found Pfizer to be 87% effective against the variant.

However, on Monday, a study out of Israel said the effectiveness of the Pfizer vaccine was 64% against all coronavirus infections.

The difference in numbers have some vaccinated against the COVID-19 virus confused. If they are fully vaccinated with the Pfizer vaccine, are they protected?

“We just have to take everything together as little pieces of a puzzle, and not put too much weight on any one number,” Natalie Dean, a biostatistician at Emory University, told The New York Times.

The Times story goes on to explain that not all studies are conducted in the same way, and that this is often the reason for the differing results.

“I am afraid that the current Israeli MoH (Ministry of Health) analysis cannot be used to safely assess it (Pfizer’s effectiveness), one way or another,” Uri Shalit, a senior lecturer at the Technion Israel Institute of Technology, wrote on Twitter.

Dr. Marc Lipsitch, a public health researcher at the Harvard T.H. Chan School of Health, put it another way.

“If there are five studies with one outcome and one study with another, I think one can conclude that the five are probably more likely to be correct than the one,” Lipsitch told the Times.

As for the Moderna vaccine, the Canadian study released on Saturday found that it was 72% effective 14 days after the first dose. There was not enough data to determine the effectiveness after two doses.

5. Do you need to wear a mask again?

If you are fully vaccinated, CDC guidelines say you no longer need to wear a face mask. However, the WHO in June underscored its recommendation that everyone should wear masks to stem the spread of the virus.

White House Chief Medical Adviser Dr. Anthony Fauci said Sunday that even those who’ve had two doses of the vaccine should still wear a mask when traveling to places with low vaccination rates.

People who are not vaccinated are encouraged to continue wearing face masks.