Delta Plus Variant

This post was last updated on September 2, 2021.

Viruses mutate a lot, and SARS-CoV-2 is no exception. © NIAID-RML Viruses mutate a lot, and SARS-CoV-2 is no exception.

If there’s one thing we can count on in life, it’s change, and viruses are no exception. Variants of the original SARS-CoV-2 virus have popped up in different corners of the world and while that might sound a bit scary, it’s actually perfectly normal, or even “humdrum” as one Nature study puts it.

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While virologists predicted all along that the virus that causes COVID-19 would mutate, what scientists still don’t know exactly is what these variations might mean for how infectious or deadly the virus is. And while we know a handful of COVID-19 variants have circulated throughout the US, pretty much unnoticed by the general public, some variants—particularly the alpha and beta variants, which originated in the UK and South Africa, respectively, and now the delta variant—share some more atypical characteristics that seem to make them more infectious. Currently, delta is making headlines due to its extra-transmissibility and recent upticks in cases across the US.

Here’s what you need to know about mutated versions and COVID-19.

The variant of most recent concern is the delta variant, a spin-off of the B.1.617 lineage which also includes the Kappa variant, which was first identified in India in October 2020, and has since spread to Britain, the US, and Israel. Delta is currently the most common variant in the US and has been shown to be incredibly transmissible—even more so than the common cold. Scientists have estimated that the original strain of the novel coronavirus had a reproductive number (R0) of about 1.5 to 3.5, meaning each sick person infects, on average, another one to four people. The delta variant, though, seems to be even more infectious than that. Researchers estimate that each sick person will infect about seven people. That makes it twice as infectious as the original strain and almost as contagious as the chickenpox.

Experts are still determining whether or not delta makes people sicker than other variants, but almost all hospitalizations and deaths due to the variant are in unvaccinated populations.

“As older age groups get vaccinated, those who are younger and unvaccinated will be at higher risk of getting COVID-19 with any variant,” Inci Yildirim, a Yale Medicine pediatric infectious diseases specialist and vaccinologist, said in a press release. “But delta seems to be impacting younger age groups more than previous variants.”

The lineage that includes delta and kappa is known for two major mutations—E484Q and L452R, the first of which may help the virus evade antibodies, according to The New York Times. 

The delta variant in particular has traveled to over 60 countries and triggered a spike in infections in places like the UK. In Singapore, the mutation accounted for 95 percent of variant local COVID samples, Bloomberg reports. Additionally, COVID patients in India, where the variant is especially prevalent, are experiencing rarer symptoms from COVID-19 like stomach pain, nausea, vomiting, loss of appetite, hearing loss, and joint pain. Ganesh Manudhane, a Mumbai cardiologist, told Bloomberg in June that he has seen increasing cases of microthrombi, which are clots in small blood vessels, so severe that gangrene develops, which can be life-threatening. 

“I saw three to four cases the whole of last year, and now it’s one patient a week,” Manudhane told Bloomberg.

There are also concerns about the current vaccines’ efficacy against the delta variant. One study showed that two Pfizer doses were 88 percent effective against delta, compared to 93 percent effective against the UK-originated alpha strain. One study found that the J&J vaccine may be less effective at fighting off delta, too.

"It is by far the most contagious variant of this virus that we have seen throughout the whole pandemic," Ashish Jha, dean of the Brown University School of Public Health, told the TODAY show on June 9. "It is what has caused huge spikes in India, and it's causing a serious increase in cases in the UK despite the fact they're very vaccinated. So it really is a problem."

Researchers have also been looking into how much of the virus people who become infected with delta have in their respiratory system—what's known as viral load. Some studies suggest that people infected with delta can have as much as 1,000 times the amount of the virus as an infection with another variant would provide, according to The New York Times. That sounds scary, but what researchers are still trying to figure out is how that translates to how infectious that person is. The data on that is still not entirely clear.

But to stay safe, continuing with tried and true methods to prevent transmission—even if you are vaccinated—such as wearing masks, frequently washing your hands, social distancing, and of course getting vaccinated, will help prevent delta's spread.

[Related: Why you should recommit to hand-washing to help prevent COVID]

The Mu variant was added to the WHO list of "variants of interest" on August 30 after being spotted in 39 countries—including 2,065 cases in the US. The WHO bulletin reads that this new variant “has a constellation of mutations that indicate potential properties of immune escape," meaning that it has the potential to evade immunity of even vaccinated or recovered people. Right now, the variant only makes up 0.1 percent of the sequenced cases of COVID across the globe, but has seen continuous upticks in Colombia and Ecuador.

The variant was first discovered back in January, and luckily hasn't had the same power as delta when it comes to infecting people all over the world. "If mu was truly a really bad variant, we would have expected to have started to see indications of this, and we haven’t yet," writes Paul Griffin, an associate professor of infectious diseases and microbiology at Australia's University of Queensland, in The Conversation. If mu becomes more of a problem, it will join the ranks of "variant of concern" alongside alpha, beta, gamma, and delta. The WHO reports that it is "unlikely" that mu has higher transmissibility than delta, but they state that Mu shows reduced vaccine efficacy similar to Beta.

As of September 8, mu has now been detected in just about every state in the United States, with the exception of Nebraska. Some states have more cases than others; according to Newsweek, California has the highest number of cases of the mu variant, and Maine, Connecticut, and Florida also have a higher number of mu variant cases than other states. However, the overall rate of COVID infections from the mu variant is extremely low. Even in California, mu makes up just 0.2 percent of sequenced COVID cases.

This week, scientists in South Africa have identified a new variant they've called C.1.2. Not much is known yet about this variant, though. On August 24, researchers reported their findings in a pre-print (not yet peer-reviewed) study online, detailing that the new variant had first been identified in May of 2021 and has "since been detected across the majority of the provinces in South Africa and in seven other countries spanning Africa, Europe, Asia and Oceania."

 The good news is that as of right now, C.1.2 is not circulating widely. The delta variant is still dominant in many parts of the world, including the United States as well as in South Africa, where C.1.2 was first found. However, scientists are keeping tabs on this new variant, particularly because it has many mutations in its genome that are similar to those found in other variants that researchers are worried about, such as the delta variant.


Video: Contact tracing needed amid delta variant surge, expert says (WBAL TV Baltimore)

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