Delta is spreading in SC. What you should know about the most-contagious COVID variant

The highly contagious delta variant, also known as B.1.617.2, is a “big concern” for South Carolina, state health officials said.

The variant, first detected in India last year, has spread rapidly across the globe and now accounts for more than half of all new COVID-19 cases in the United States.

Because the delta strain is so transmissible, states with low vaccination rates, like South Carolina, are particularly vulnerable, S.C. Department of Health and Environmental Control officials said.

As of Thursday, only 43.5% of eligible South Carolina residents had been inoculated, according to DHEC data.

While only a small number of delta cases have been identified in South Carolina to date, DHEC officials fear the variant, which is driving COVID-19 spikes in other parts of the country with comparable vaccination rates, could soon spark an outbreak in the Palmetto State.

“Missouri is having a frightening surge in COVID-19 cases, overwhelming some of their hospital systems, and 96% of those new cases are delta variant,” assistant state epidemiologist Jane Kelly said during a media briefing last week. “We don’t want that happening here. We need to increase our statewide vaccination rates.”

Here’s what you need to know about the delta variant in South Carolina.

Why is delta more concerning than other COVID-19 variants?

Delta has multiple mutations that make it more contagious and better able to evade the body’s immune defenses, giving it an advantage over other strains.

“This particular delta variant is faster, it is fitter, it will pick off the more vulnerable more efficiently than previous variants, and therefore if there are people left without vaccination, they remain even at further risk,” Mike Ryan, executive director of the World Health Organization’s health emergencies program, said last month.

Scientists estimate the delta variant is between 40% and 60% more transmissible than the alpha variant, which itself is 50% more transmissible than the original coronavirus strain identified in Wuhan, China.

Delta also appears to sidestep part of the body’s vaccine-induced immune response, leading to lower efficacy rates for the COVID-19 shots currently on the market.

More research is needed to determine whether delta causes more severe illness than other coronavirus strains, but experts regard it as more dangerous because it can burn through unvaccinated populations quickly due to its hyper-transmissibility.

“The most important thing that’s different about the delta variant is how much easier it is to spread,” Kelly said. “It’s got a better spike protein adhesion factor, so it’s just better to adhere and get into cells.”

Does the delta variant cause different symptoms?

Some evidence suggests delta variant symptoms differ somewhat from the symptoms most commonly associated with COVID-19, such as fever, cough and loss of taste or smell.

Headaches, sore throats and runny noses are more common in delta cases, according to data collected in Britain, where the variant comprises nearly all new cases.

Overall, however, the symptoms remain similar.

Kelly, the DHEC epidemiologist, said she believed the difference in delta’s reported symptoms was likely the result of ascertainment bias, which occurs when the data sampled is not representative of the target population.

“There’s nothing about the delta variant that makes me think from a biological point of view or from a medical point of view that it should cause different symptoms or a different presentation,” she said.

Robert Bollinger, an infectious disease doctor at the Johns Hopkins University School of Medicine, surmised that the variation in symptoms may have more to do with the people being infected than the virus itself.

“People getting infected now are a lot younger than they were with the earlier variants, because the older people are vaccinated at a much higher rate,” he told the LA Times. “So are some of the differences that are being reported related to the virus, or just the fact that it’s younger people getting infected? I don’t think we really know that yet.”

How many delta cases are there in South Carolina?

As of July 7, DHEC had confirmed 12 delta cases in South Carolina, two more than the week prior. (DHEC updates the number of variants identified in the state every Friday).

Seven of the 12 confirmed delta cases were in the Lowcountry, four were in the Midlands and one was found in the Pee Dee region. No delta cases have been identified in the Upstate, according to DHEC.

Because COVID-19 cases must be genomically sequenced to identify their characteristics, and the state sequences only a tiny fraction of its cases, the true number of delta cases in South Carolina is undoubtedly greater than 12.

“We know that there are more instances of the delta variant in our state than what we’ve identified since not every COVID-positive sample is sequenced for variants,” Kelly said last week. “We know delta variant is here. We’re concerned it’s going to spread quickly just as it has done in other states with low vaccination rates.”

Of the 195 samples sequenced at DHEC’s public health laboratory in June, 78% were identified as variants of concern, a designation the CDC uses to describe strains that show evidence of increased transmissibility, more severe disease or resistance to vaccines or medical treatments.

Just over 5% of the variants of concern DHEC identified were of the delta variety.

State health officials could not immediately provide the percentage of delta samples sequenced this month, but it is believed to have increased.

“We are at 10% (delta), but are starting to see that we’re going regionally significantly higher,” Dr. Helmut Albrecht, medical director of the Center for Infectious Diseases Research and Policy at Prisma Health and the University of South Carolina, said Wednesday. “It will be the predominant strain in South Carolina, as well, within the next couple weeks.”

How effective are vaccines against the delta variant?

All three coronavirus vaccines on the market in the United States are highly protective against delta.

A series of recent studies conducted in Britain, Scotland and Canada found that two doses of the Pfizer-BioNTech vaccine were between 79% and 88% effective against the variant.

Moderna and Johnson & Johnson also have announced that their vaccines remain protective against delta, albeit with slight drops in potency.

A single shot of the Pfizer vaccine, however, was only 33% effective against symptomatic delta cases, the Public Health England study found. That’s down from a 50% one-dose efficacy against the alpha variant, the health agency reported.

A study published last month in the journal Nature also found significant differences in the immune responses of people who had received just one vaccine dose compared to two. Only 13% of people effectively neutralized the delta variant after a single dose of the Pfizer vaccine, but 94% were able to do so after two doses, researchers found.

When it comes to the delta variant, “It’s very clear that one shot of the mRNA vaccines — the Pfizers and the Modernas — is not enough,” Albrecht said.

Will booster shots be needed to combat the delta variant?

The short answer is not at this time, but possibly in the future.

Israel recently began offering COVID-19 booster shots to its most vulnerable citizens after its Ministry of Health released data showing that the Pfizer vaccine was only 64% effective at preventing all coronavirus infections, down from 95% in May, before delta became widespread.

Pfizer, which said its own studies are consistent with Israel’s findings, last week announced plans to seek U.S. authorization for a third COVID-19 vaccine dose to boost immunity and protect against the delta variant.

Federal health officials responded to the company’s announcement by reiterating that booster shots for fully vaccinated Americans were not currently necessary.

“We continue to review any new data as it becomes available and will keep the public informed,” the U.S. Centers for Disease Control and Prevention and the U.S. Food and Drug Administration said last week in a joint statement. “We are prepared for booster doses if and when the science demonstrates that they are needed.”

DHEC has echoed federal health experts on the issue of booster shots.

“Some individuals who have severe immunocompromise, for example people who are organ transplant recipients, have benefited from getting a third shot to increase their immune response,” Kelly said last week. “But for the general public, there’s no need for booster shots at this time.”

What are DHEC recommendations for protecting against delta?

The public health recommendations for protection against the delta variant are the same as for any coronavirus strain, Kelly said.

“Wear a mask, avoid crowded public settings, keep your distance, wash your hands,” she said. “But the most-effective thing you can do, by far, is get vaccinated.”

While the World Health Organization last month recommended that fully vaccinated people wear face masks and practice social distancing due to the delta variant’s spread, neither the CDC nor DHEC has adopted similar masking guidance for vaccinated individuals.

Michael Sweat, director of the COVID-19 Epidemiology Intelligence Project at the Medical University of South Carolina in Charleston, said he agrees with the CDC’s decision on masks.

“The vaccine really does work well against this variant,” he said. “There is a risk you’re going to catch it and get sick, but you’re not likely to get a very serious infection.”

This story will be updated.