By Denise Chow - NBC News
A more contagious variant of the coronavirus, known as delta, which is spreading in the United States and around the world,
has led to an increase in cases in some countries and many nations to impose confinement orders
.
The delta variant, first detected in India, already accounts for 25% of new COVID-19 cases in the United States and is on its way to becoming the dominant version of the virus circulating in the country, according to the Centers for Disease Control and Prevention (CDC).
Dr. Anthony Fauci, an infectious disease expert in the country and director of the National Institute of Allergy and Infectious Diseases, called the delta variant the "greatest threat" to eliminate COVID-19 in the United States.
[Fauci insists that the vaccinated do not need a mask despite the delta variant]
This is what is known so far about the delta variant.
Why is it a concern?
The delta variant was designated in May as "worrisome" by the World Health Organization. The designation is used when there is more evidence that it is more communicable, causes more serious disease, or reduces the effectiveness of vaccines or treatments. In the United States, the CDC declared delta "concerning" on June 15.
The delta variant of COVID-19 already has a presence in all 50 states and Washington DC
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Research suggests that
delta (known as B.1.617.2) is the most contagious of all the variants known to date
, including the highly communicable alpha first identified in Britain.
Public health officials in the United Kingdom, where delta accounts for more than 95 percent of new COVID-19 cases, have said the variant could be 40 to 60 percent more transmissible than alpha, although it is they continue to carry out studies.
[Follow our coverage of the coronavirus pandemic]
One of the ways epidemiologists determine the transmissibility of a new variant is to examine what is known as the secondary attack rate.
This involves
tracking the close contacts of people who have been infected with different versions of the virus
and seeing how many others have tested positive.
"Suppose we have 10 people with 20 close contacts. With one variant, maybe we will see five of those close contacts get infected. If a second variant is 50 percent more transmissible, that number would be 50 percent higher." noted Dr. David Dowdy, associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.
"So in this case, I would expect 7.5 of those contacts to be infected, after taking into account vaccination status and if they had a previous infection," he added.
A passenger walks into one of the terminals at O'Hare International Airport in Chicago this Friday, July 2, 2021. AP
What is the 'delta plus' variant?
It's not unusual for a virus to mutate and evolve as it spreads, and scientists have long warned that
other worrisome variants could emerge with new outbreaks
.
In India, researchers looked at separate delta mutations in a sublineage of the virus they called delta plus.
While it has not yet been designated as a variant of concern by the WHO or the CDC, cases involving delta plus have been reported in 11 countries, including the United States.
It is not yet clear, however, whether this variant carries additional risks or is associated with increased transmissibility.
Does the delta variant cause more serious symptoms or illnesses?
More research is needed, but
there is evidence that the delta variant may cause more serious disease
.
A study published June 14 in
The Lancet
examined the impact of the delta variant in Scotland, where it had become the dominant strain.
The researchers found that the risk of hospitalization for COVID-19 sharply doubled for patients infected with the delta variant, compared to those infected with the alpha variant.
Pfizer studies the effectiveness of its vaccine against COVID-19 in children 5 years and older
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"If to compare we look at the original strain, the variant (alpha) from the United Kingdom and now the delta, we are noticing
that there is a difference in transmissibility, as well as the potential for more dangerous results
," said Dr. Alejandro Pérez -Trepichio, an internal medicine specialist in Naples, Florida.
Researchers in the UK have reported a change in symptoms that may be associated with the delta variant. Statistics from a mobile app downloaded by four million people in the UK to report symptoms, vaccination status and other daily demographic information, found that
the most common ailments from the coronavirus are now headache, sore throat, runny nose and fever
, similar to those experienced with a bad cold.
Some doctors in the United States have encountered a similar change, as shortness of breath, coughing and other lung problems remain the most common symptoms of COVID-19, first identified in Wuhan, China.
However, some doctors have noticed more upper respiratory problems, such as congestion, runny nose, and headaches, with recent infections.
[A new mutation of the delta variant of the coronavirus is detected in the United States]
It is
not yet clear why cold-like symptoms are increasingly being reported, or if there is a link to the delta variant
.
The implications of such a change, if it exists, are also not known.
A wide range of symptoms have been associated with the coronavirus, and the CDC includes congestion and a runny nose on its list of possible COVID-19 symptoms.
Where is it spreading?
The World Health Organization (WHO) reported that the delta variant has spread to more than 95 countries.
"In every country that he has entered so far, he has seen an escalation in the cases where he has neglected the variant that was dominant," Fauci said Tuesday in an interview with NBC's Nightly News.
[The CDC lists the delta variant of the coronavirus as "worrisome"]
Cases involving the delta variant have been confirmed in all 50 US states and it is especially dangerous in parts of the country with low vaccination rates.
Similarly, the variant is driving new outbreaks around the world.
Several cities in Australia, including Sydney and Brisbane, imposed restrictions
to slow the spread of the virus.
Delta variant of COVID-19 spreads rapidly in California
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Bangladesh imposed a nationwide home confinement order after an increase in infections and the highest number of deaths from the pandemic in a single day has been reported to date.
A night curfew is maintained in South Africa and new travel restrictions have been put in place in Germany, Hong Kong and Taiwan to limit flights from areas where the delta variant is widespread.
Are vaccines effective against this variant?
Vaccines in use appear to offer good protection against the delta variant, and most scientists agree that
people who are fully vaccinated are likely to be at little risk.
[Pfizer studies the effectiveness of its vaccine against COVID-19 in children 5 years and older]
Modern pharmaceutical company announced on Tuesday that its vaccine is effective against the delta variant.
The results were based on blood samples from fully vaccinated people and showed that these individuals produced protective antibodies against some of the circulating variants, including delta.
Although details of the results of all available vaccines have not been made public, equally promising results have been found with the Pfizer-BioNTech and AstraZeneca vaccines.
An analysis published June 14 by Public Health England found that two doses of the Pfizer-BioNTech vaccine were
96% effective
against hospitalization for the delta variant and that two doses of the AstraZeneca vaccine were
92% effective
.
The delta variant of the coronavirus is spreading in the states with the least vaccinated
June 28, 202101: 40
A previous analysis by the same agency found that a single dose of the vaccine was less effective against symptomatic disease caused by the delta variant compared to alpha, highlighting the importance of receiving both injections in a two-dose regimen.
And in the cases of the so-called progressive infections, when a fully vaccinated person is infected, the cases are usually mild.
In Israel, where about 60% of the population is fully vaccinated, a recent increase in coronavirus cases associated with the delta variant - including infections among vaccinated people -
also did not reflect an increase in hospitalizations
.
[Fauci insists that the vaccinated do not need a mask despite the delta variant]
A study in South Africa, which tracked more than 360,000 healthcare workers vaccinated with Johnson & Johnson's single-dose vaccine, found that
94% of new infections were mild
.
The results, while preliminary, suggest that the Johnson & Johnson vaccine offers good protection against delta and other so-called worrisome variants.
“The top-level message is that vaccines work,
two doses work better than one, and the more people vaccinated, the better,
” Dowdy emphasized.
While there is likely not much cause for concern among people who are fully vaccinated, public health officials are concerned about outbreaks in places with low vaccination rates.
In the United States, COVID-19 cases increased 10% or this week compared to the previous week, an increase that was likely driven by the spread of the delta variant and repeated vaccinations, according to the CDC.
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Sectors in the southeast and midwest of the country, where the vaccination process has been delayed, remain vulnerable, health sector officials reported.
This kind of uneven picture in vaccination
could result in surges locally
as the delta variant takes hold, Fauci said.
"That is what worries us. We do not want that to happen," he added.
Does everyone need to wear masks again?
In response to the spread of the delta variant, the
WHO warned that people, regardless of their vaccination status, should continue to wear face masks
.
Meanwhile, the CDC's advice guide has maintained that fully vaccinated people can stop wearing the masks, though the agency acknowledged that
regulations at the local level can change depending on the situation.
[The Supreme Court maintains the moratorium on evictions due to the coronavirus pandemic: the benefit will expire in July]
Earlier this week, Los Angeles County, one of the largest and most populous in the country, recommended that everyone, including those who are fully vaccinated, wear masks indoors.
People with and without masks in the Grand Central Market in Los Angeles, California, as the WHO urges those vaccinated to wear masks again due to the rapid spread of the delta variant.AFP via Getty Images
Fauci said the CDC's guidance on
mask use likely won't change unless new evidence emerges that warrants an update
.
"If there is any modification that induces a change in the recommendation, it will happen," he said.
"But for now, the CDC's recommendation is that if [the person] is fully vaccinated, they are protected and do not need to wear masks outdoors or indoors."
Fauci added, however, that some
older people or people with pre-existing conditions may feel more comfortable wearing masks
in places where there is an increase in infections.
For Dowdy, it ultimately comes down to comfort and common sense, but he added that people should have confidence that vaccines offer good protection.
“It makes sense to use caution, but I am concerned that by saying that everyone should wear masks again, we are sending the message that we do not believe these vaccines are working.
We would not be sending a good message,
”stressed Dowdy.