- Scientists believe the Delta variant is being transmitted up to 60 percent faster than the Alpha variant, which was thought to spread 50 percent quicker than the original strain that hit in 2019.
- Experts think the COVID-19 Delta variant is much more contagious than the flu and chickenpox, and on par with the measles.
- In a
recent paper, people with the Delta variant had much higher viral loads than those who had the original version of the coronavirus
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub and follow our live updates page for the most recent information on the COVID-19 pandemic.
Health officials recently labeled the COVID-19 Delta variant the fastest and fittest version of the coronavirus we’ve seen so far.
Now, the Centers for Disease Control and Prevention (CDC) is expected to release new evidence on Friday suggesting that the variant may be as transmissible as chickenpox.
A recently leaked document from the CDC also said the Delta variant is more transmissible than the common cold, 1918 Spanish flu, smallpox, Ebola, MERS, and SARS, according to the New York Times.
The document also suggests the Delta variant may cause more severe illness. However, there isn’t enough data to say that’s definitely the case.
The CDC also suspects that vaccinated people who get breakthrough cases may have the potential to transmit the virus to others.
People who get the Delta variant reportedly have higher viral loads compared to those with the original strain. Researchers are currently looking into how viral loads in vaccinated people translate to how transmissible it is.
The COVID-19 vaccines remain highly effective against severe illness and death from developing the disease.
If you’re unvaccinated, the best way to protect yourself from severe complications due to the Delta variant is to get vaccinated as soon as possible — and encourage those around you to do so, too.
The Delta variant, which was identified in December 2020, quickly moved across the globe, becoming the dominant strain in India, the United Kingdom, and now the United States.
Scientists believe the Delta variant is spreading up to 60 percent faster than the Alpha variant, which was believed to spread 50 percent faster than the original strain that hit in 2019.
According to Dr. Benjamin Neuman, the chief virologist at Texas A&M University’s Global Health Research Complex, there’s reason to believe it’s the most contagious virus we’ve seen in years.
“I believe every other communicable disease is down over the past year due to the precautions we have taken, but SARS-CoV-2 continues to grow. That seems like a clear indication that SARS-CoV-2 is the most infectious human [virus] currently in circulation,” Neuman told Healthline.
Dr. Sharon Nachman, a pediatric infectious diseases specialist and the chief of the Division of Pediatric Infectious Diseases at Stony Brook Children’s Hospital in Stony Brook, New York, said the Delta variant is estimated to be up to 60 percent more contagious than the original coronavirus that was detected in 2019.
Nachman suspects Delta is much more contagious than the flu and on par with measles.
The biggest clue that this variant is more infectious than the flu is
There was essentially no flu season this year, thanks to all the precautions we took to prevent COVID-19.
But, despite the precautions, the Alpha and Delta variants continued to be contracted, affecting millions of people.
“The fact that COVID-19 continues to spread in conditions where the flu is barely detectable shows how much more infectious SARS-CoV-2 is compared to influenza A and B viruses,” Neuman told Healthline.
The level of natural immunity in our population also affects how infectious a virus is.
With measles, there’s widespread immunity thanks to high vaccination rates and a very effective vaccine.
We’ve also got a lot of immunity against chickenpox and the flu.
But with COVID-19, unvaccinated people who haven’t had the disease remain vulnerable.
“If your cells see it, they will get infected. And as we have seen, infection (in unvaccinated individuals) means more will get hospitalized and more will die,” Nachman said.
According to Nachman, these differences can also be traced back to the viruses’ abilities to transmit from a distance.
Measles is infectious from 60 feet away, and simply walking into a room within an hour or two after someone with measles was there would give you measles.
According to the
Chickenpox is infectious from 20 feet, and the flu is predominantly spread from close contact.
The degree to which a virus is airborne depends on its size, said Nachman. The measles virus is very small and able to stay suspended in the air for longer and remain contagious.
SARS-CoV-2 is a larger particle, so it’s not able to stay suspended in the air for quite as long, according to Nachman.
However, there are other factors at play.
“When I think about a large closed room like a concert, where no one is wearing a mask and all are singing, the likelihood of spread is much higher since it’s an ongoing viral load that is getting aerosolized and circulating in the closed room,” Nachman said.
It’s not clear, said Neuman.
“There are two mutations at either end of the clamp-like region that the virus uses to grip our cells that may explain at least part of the spread of Delta, but there are many more mutations in other genes whose function is not clear, which could also be involved,” Neuman said.
According to Nachman, those mutations make it easier for the spike protein to enter our cells and infect them.
According to a preprint article, people with the Delta variant have much higher viral loads than those who had the original version of the coronavirus.
With higher viral loads, it’s believed that people who contract SARS-CoV-2 shed more virus, making it easier to transmit the virus to those around them.
“The individuals with Delta have higher viral loads, so the virus is not only more transmissible, but there is more of it in each cough or sneeze to try and get into your cells,” Nachman explained.
Neuman is concerned about how contagious the Delta variant is, but what worries him even more is how easily new variants have emerged and spread.
“The virus changes as it grows, so more cases mean more mutations,” Neuman said.
Evidence continues to show that the vaccines remain highly effective against severe disease, hospitalization, and death.
Vaccination, in addition to wearing masks, can only impact transmission at an individual level, though.
To reduce the spread of the Delta variant, the vaccination rate needs to increase dramatically so we can deny the coronavirus the opportunity to transmit to new people and grow.
That’s the only way we can beat COVID-19 in the long term, according to Neuman.
“We have all the tools we need to stop COVID-19, and it would be a tragedy if we did not use them,” Neuman said.
Health officials recently labeled the Delta variant the fastest and fittest version of the coronavirus we’ve seen so far. New information from the CDC reports that this variant may be as infectious as chickenpox.
The Delta variant is thought to be up to 60 percent more transmissible than the original version of the coronavirus.
It’s also believed to be more contagious than the flu and chickenpox, and likely on par with measles.
The COVID-19 vaccines have some protection against the Delta variant — but vaccination rates need to increase dramatically in order for us to deny the variant a place to grow.