Delta plus variant: What it is and how it differs from other coronavirus strains

South Korea’s Disease Control and Prevention Agency (KDCA) announced on Tuesday that it had detected its first two cases of a new "delta plus" coronavirus variant, Reuters reported

So far, reports of the new variant are limited, but there have been some cases identified in multiple countries including the U.K., Portugal and India.

"The first case (in South Korea) was identified in a man in 40s who has no recent travel records," the KDCA told Reuters. 

What is the delta plus variant?

The delta plus variant differs from the primary delta variant that scientists believe is the most contagious coronavirus mutation so far in the ongoing global COVID-19 pandemic. 

New evidence from the U.S. Centers for Disease Control and Prevention released on July 29 revealed that the primary delta variant can be as contagious as chickenpox. The delta variant, first detected in India, has quickly become the dominant coronavirus strain wherever it has landed, including in the U.S.

RELATED: UK scientists say variant that can evade COVID-19 vaccines ‘almost certain’

The delta plus variant is unique in that it has acquired the spike protein mutation called K417N, which was first identified in the beta variant that originated in South Africa. 

Researchers worry that the additional spike mutation combined with other characteristics of the original delta variant could help the delta plus variant evade antibodies harnessed by vaccines to fight it. 

How many coronavirus variants are there?

The CDC says it is monitoring four variants of the novel coronavirus that have been detected in the U.S.:

  • B.1.1.7 (alpha): This variant was first detected in the United States in December 2020. It was initially detected in the United Kingdom.
  • B.1.351 (beta): This variant was first detected in the United States at the end of January 2021. It was initially detected in South Africa in December 2020.
  • P.1 (gamma): This variant was first detected in the United States in January 2021. P.1 was initially identified in travelers from Brazil, who were tested during routine screening at an airport in Japan, in early January.
  • B.1.617.2 (delta): This variant was first detected in the United States in March 2021. It was initially identified in India in December 2020.

"These variants seem to spread more easily and quickly than other variants, which may lead to more cases of COVID-19. An increase in the number of cases will put more strain on healthcare resources, lead to more hospitalizations, and potentially more deaths," according to the CDC.

Meanwhile, health officials are also keeping an eye on the lambda variant, which was first identified by the World Health Organization on June 14, 2020 involving a case in Peru that was documented in December 2020. 

RELATED: COVID-19 lambda variant: What to know about the coronavirus strain

WHO officials said not much is known about the projected impact of the lambda variant, but there is the potential of increased transmissibility or possible increased resistance to neutralizing antibodies compared to the original COVID-19 strain. Researchers said more studies are needed to understand the variant.

Early studies, including one from New York University published July 2, suggest lambda may be a bit resistant to antibodies produced by the mRNA vaccines from Pfizer-BioNTech and Moderna, but concluded it is not resistant enough "to cause a significant loss of protection against infection."

"So far we have seen no indication that the lambda variant is more aggressive," Jairo Mendez-Rico, a WHO virologist, told Deutsche Welle. "It is possible that it may exhibit higher infection rates, but we don't yet have enough reliable data to compare it to gamma or delta."

Should I be worried about the delta plus variant?

Viruses constantly mutate, and most changes aren’t concerning. But the worry is that unchecked spread could fuel mutations and produce a variant that’s even more contagious, causes more severe illness or evades the protection that vaccines provide.

It’s why experts say making vaccines accessible globally is so critical. And they note the importance of being fully vaccinated; getting just one dose of the two-dose vaccines isn’t as protective against the delta and now the new delta plus variant.

Studies so far seem to indicate that vaccines are still effective against most coronavirus variants, though less is directly known about the specific effect of current vaccines against the delta plus variant. 

A recent study from the Yale School of Public Health and the Commonwealth Fund estimates that rapid rollout of COVID-19 vaccines prevented nearly 300,000 additional deaths.

Researchers say without the current vaccination program in place, by the end of June 2021 there would have been an additional 1.25 million hospitalizations. 

"If the U.S. had achieved only half the actual pace of vaccination, there would have been nearly 121,000 additional deaths and more than 450,000 additional hospitalizations," study authors wrote. 

On July 28, Pfizer shared data about a third dose of its COVID-19 vaccine that suggests it "strongly" boosts protection against the more contagious delta variant of the coronavirus, which has driven a recent surge in U.S. cases and hospitalizations. 

A separate study published in the New England Journal of Medicine on July 21 revealed that two doses of the Pfizer vaccine are 88% effective against the delta variant. 

Researchers found with the Pfizer vaccine, the effectiveness of two doses was 93.7% among people with the alpha variant and 88% among those with the delta variant.

RELATED: Pfizer vaccine 88% effective against delta variant, study finds

"Overall, we found high levels of vaccine effectiveness against symptomatic disease with the delta variant after the receipt of two doses," the study authors wrote.

But effectiveness after only one dose of the vaccine was notably lower — only 30.7% effective against the delta variant — driving home previous suggestions by officials to obtain two doses of a vaccine.

"Our finding of reduced effectiveness after the first dose would support efforts to maximize vaccine uptake with two doses among vulnerable groups in the context of circulation of the delta variant," the authors continued.

Experts believe the delta variant spreads more easily because of mutations that make it better at latching onto cells in human bodies. On its website, the CDC notes "increased transmissibility" with the delta variant and the potential for it to make certain monoclonal antibody treatments less effective.

Even the ChAdOx1 nCoV-19 vaccine, which was manufactured in India and is less effective than the Pfizer or Moderna vaccines, is effective at preventing serious illness from the disease, according to a recent study. The study, published in the medical journal The Lancet on July 1, found that India’s vaccine offered 71% efficacy and protection against hospitalization from COVID-19.

But with current breakthrough infections happening in the U.S. and vaccination rates stalling, there are growing concerns that emerging mutations — including delta plus — could develop and overtake even the hyper-contagious delta variant. 

Scientists who are part of a government scientific advisory group from the United Kingdom said it is "almost certain" a new COVID-19 variant will emerge that will render current vaccines ineffective.

The advisory group published a research and analysis paper on the long-term evolution of COVID-19 on July 26. The paper explores several hypothetical, but highly likely, scenarios of what humanity can expect in the long-term from COVID-19 based on current trends and data.

Scientists wrote that since the eradication of the novel coronavirus is "unlikely," there are sure to be new variants that emerge and infect the population at large.

"For this purpose, we consider mutations in the ‘body’ of the virus (the viral genes that are expressed in infected cells and control replication and cell response), that might affect virus fitness and disease severity, separately from mutations in the spike glycoprotein that might affect virus transmission and antibody escape," according to the analysis.

Authors hypothesized that since COVID-19 is still prevalent among the larger population, there is a very high likelihood a new variant will emerge, creating a strain of the novel coronavirus that can evade current vaccines. The new variant will create a need for a modified vaccine, which could likely come in the form of a yearly booster shot, similar to the flu vaccine, the scientists said.

But it’s not yet clear if the delta plus variant poses a higher risk to people who are vaccinated. In India, where the primary delta variant originated, experts are keeping a close eye on the delta plus strain’s evolution.

Speaking to India Today, Dr. Rakesh Mishra, director of India’s Centre For Cellular And Molecular Biology said, "Delta is the most widespread variant in the country, we don't know if the new variant will overtake the parent. But we are keeping a watch on it to prevent another unprecedented surge," Mishra added. 

Is the delta plus variant more severe?

So far, there is no conclusive evidence to suggest that the delta variant or the delta plus variant are more deadly than the original coronavirus strain that was first detected during the onset of the pandemic. 

But in internal documents obtained by multiple news agencies on July 29, the CDC said it cannot rule out increased COVID-19 severity in those infected with the delta variant.

RELATED: CDC: New data suggests vaccinated people could transmit delta variant

A recent study published on July 7 and led by Chinese epidemiologist Jing Lu at the Guangdong Provincial Center for Disease Control and Prevention in Guangzhou, China shed light on why the delta variant is of grave concern to the world’s health care system and why it is more transmissible than other mutations. 

Study authors noted that one characteristic that makes the variant so worrisome is its high viral load.

Researchers found that the delta variant contains 1,000 times more viral material than that of the original novel coronavirus variant that infected much of the global population during the onset of the global pandemic last year.

RELATED: Delta variant viral load 1,000 times higher than original coronavirus strain

CDC Director Dr. Rochelle Walensky said that the agency has learned that even fully vaccinated people can transmit the delta variant to others, given the strain’s high viral load.

"We are actively conducting outbreak investigations of what’s occurring in places that are having clusters... What we’ve learned in that context, is when we examine the rare breakthrough infections and we look at the amount of virus in those people, it’s pretty similar to the amount of virus in unvaccinated people," Walensky said, speaking to reporters on July 27 when the health agency issued new recommendations that vaccinated people return to wearing masks indoors in parts of the U.S. where the virus is surging. 

RELATED: CDC: Less than 1% of breakthrough COVID-19 cases led to hospitalization or death

Walensky also said that most of the cases and hospitalizations related to COVID-19 are coming from people who are not yet vaccinated. She pleaded with Americans to get inoculated in hopes of not overwhelming the nation’s hospitals.

"Of the transmission that’s happening in the country right now, a vast majority of transmission is occurring through unvaccinated people. But on the exception that might have a vaccination breakthrough, (the CDC) thought it was important for people to know they could pass the disease onto someone else," Walensky said.

According to the latest data from the U.S. Centers for Disease Control and Prevention on breakthrough COVID-19 cases, less than 1% of people who have contracted the novel coronavirus despite being vaccinated have either been hospitalized or died.

Though hospitalizations and deaths from COVID-19 breakthrough infections can happen in rare cases, the data highlights just how uncommon such cases are.

Low vaccination rates prolong the pandemic

The United States on Monday finally reached President Joe Biden’s goal of getting at least one COVID-19 shot into the arms of 70% of American adults — a month late and amid a fierce surge by the delta variant that is swamping hospitals and leading to new mask rules and mandatory vaccinations around the country.

The U.S. still has not hit the administration's other goal of fully vaccinating 165 million American adults by July 4. It is about 8.5 million short.

New cases per day in the U.S. have increased sixfold over the past month to an average of nearly 80,000, a level not seen since mid-February. And deaths per day have climbed over the past two weeks from an average of 259 to 360.

The United States recorded more than 100,000 new daily COVID-19 cases on each of the past two days, according to data collected by Johns Hopkins University. 

On Aug. 3, the U.S. recorded 127,976 new daily cases and on Aug. 4, the country counted 106,557 new daily COVID-19 cases. Between Aug. 2 and Aug. 3, new daily cases jumped from 25,141 to a staggering 127,976 new daily cases.

RELATED: New COVID-19 cases in US surpassed 100K for past 2 days

The giant leap in new daily COVID-19 cases is a stark illustration of the delta variant-driven surge in the U.S. amid mostly stagnant vaccination rates. 

Those are still well below the 3,400 deaths and a quarter-million cases per day seen during the worst of the outbreak, in January. But some places around the country are watching caseloads reach their highest levels since the pandemic began. And nearly all deaths and serious illnesses now are in unvaccinated people.

The Associated Press, Catherine Park, Megan Ziegler and Chris Williams contributed to this report.