Even as many people are growing hopeful that we’re nearing the end of the COVID-19 pandemic, and restrictions continue to be relaxed, experts warn that virus mutations could easily cause serious setbacks. 

A current top concern is the Delta variant, a strain of the SARS-CoV-2 virus that is highly contagious and may possibly cause more severe symptoms than previously seen. Here’s what we know about it so far.

The Delta Variant is More Contagious

The Delta variant was first identified in India in December 2020, then spread to Great Britain and the United States. Cases of infection have multiplied rapidly. That the virus has mutated into several different strains is no surprise to immunologists. The flu has done the same thing. 

“All viruses evolve over time and undergo changes as they spread and replicate,” said Inci Yildririm, a pediatric infectious disease specialist at Yale Medicine. What makes the Delta variant unusual is that it is 75% more contagious than the original SARS-CoV-2 virus. Each new strain of the virus has spread more quickly than the last. 

According to F. Perry Wilson, a Yale Medicine epidemiologist, Delta is spreading 50% faster than Alpha, which was 50% more contagious than the original. “Where no one is vaccinated or wearing masks, it’s estimated that the average person infected with the original coronavirus strain will infect 2.5 other people,” he explained. “In the same environment, Delta would spread from one person to maybe 3.5 or 4 other people.”

Unvaccinated People Are at Higher Risk

People who have not received a COVID-19 vaccine are most at risk. Children and young people are of particular concern, especially in states such as Alabama, Arkansas, Georgia, Mississippi, Missouri, and West Virginia, where vaccination rates are low and the infection rate is on the rise.

“As older age groups get vaccinated, those who are younger and unvaccinated will be at higher risk of getting COVID-19 with any variant,” says Yildirim. “But Delta seems to be impacting younger age groups more than previous variants.” The U.S. has not yet approved any COVID-19 vaccines for children aged 5-12, but is considering the idea.

Health Experts Fear Hyperlocal Outbreaks

According to Wilson, how many people will get the Delta variant and how fast it will spread may depend on where you live and how many people in your location have been fully vaccinated. “I call it ‘patchwork vaccination,’ where you have these pockets that are highly vaccinated that are adjacent to places that have 20% vaccination,” he said. “The problem is that this allows the virus to hop, skip, and jump from one poorly vaccinated area to another.”

A low-vaccination town surrounded by high vaccination towns could find the virus contained within its borders, warned Wilson. Too many people infected at the same time in a given area could overwhelm local health care systems and result in more deaths. “That’s something we have to worry about a lot.”

Does Delta Cause More Severe Symptoms?

While information about the severity of Delta is limited, a study from Scotland showed that the Delta variant was about twice as likely as the Alpha strain to result in hospitalization in unvaccinated individuals. Vaccines significantly reduced that risk. 

Reports have documented some different symptoms than those associated with the original coronavirus strain. “It seems like cough and loss of smell are less common,” said Yildiririm. “And headache, sore throat, runny nose, and fever are present, based on the most recent surveys in the UK, where more than 90% of the cases are due to the Delta strain.”

Do the COVID vaccines protect against the Delta variant?

Although research is ongoing, a recent Public Health England analysis of fully vaccinated participants found that at least two of the current vaccines are effective against Delta. 

• The Pfizer-BioNTech mRNA vaccine was:
  • 88% effective against symptomatic disease, and 
  • 96% effective against hospitalization from Delta

• Oxford-AstraZeneca (not an mRNA vaccine) was:
  • 60% effective against symptomatic disease, and 
  • 93% effective against hospitalization. 

Hard data on the effectiveness of other vaccines against the Delta strain is not yet available.

What the experts recommend

The doctors urge everyone who is eligible to get fully vaccinated, if at all possible, and add that it’s also important to follow CDC prevention guidelines, which are available for both vaccinated and unvaccinated people.

“Like everything in life, this is an ongoing risk assessment,” Yildirim said. “If it is sunny and you’ll be outdoors, you put on sunscreen. If you are in a crowded gathering, potentially with unvaccinated people, you put your mask on and keep social distancing. If you are unvaccinated and eligible for the vaccine, the best thing you can do is to get vaccinated.”

*Katella, K. (2021, July 5). The Delta Variant: What You Need to Know. Science Alert. http://www.sciencealert.com/the-delta-variant-has-experts-worried-here-s-what-you-should-know-about-it 

Much about the novel coronavirus, i.e., COVID-19, is still not fully understood. As research progresses and our knowledge of the virus increases, information can change rapidly. We strive to update all of our articles as quickly as possible, but there may occasionally be some lag between scientific developments and our revisions.