Understanding COVID-19’s Deadly Delta Variant – Part I: What It Is—and Why It’s So Dangerous

October 7, 2021

By Mike DuBose

As we moved into the summer of 2021, I, like many others, had high hopes that the US was winning its fight against the novel coronavirus. Although there were some holdouts, many Americans have gotten inoculated against the virus (as of September 12, 2021, nearly 63% of Americans over the age of 12 were fully vaccinated, and nearly 74% have received at least one shot), and infection rates seemed to be on a downward slope. As a researcher who has been intently monitoring COVID studies and news since the outbreak’s beginning, I was excited to see CDC data showing that the 7-day moving average for new cases had dipped down to about 11,500 by mid-June—a low that we hadn’t seen since March 2020.

Unfortunately, this trend was not to last. Thanks to the arrival and spread of the Delta variant of COVID-19 (as well as other factors like people relaxing precautions and increasing summer travel), an average of 136,500 new cases per day are occurring as of September 10, 2021, according to the most recent Centers for Disease Control and Prevention (CDC) data available. The Delta variant is now responsible for the vast majority (more than 90%) of new US COVID-19 cases, according to the CDC. Scientists are very concerned about how quickly the variant has spread through the nation, how much sicker it seems to make people than the original strain, and its apparent ability to infect even vaccinated people and children, who were thought to be safe from the previous version of COVID.

Because the Delta variant has not existed for very long, researchers and scientists have only been able to gather information on it for a short period of time. There is still a lot of confusion and speculation out there about the variant and why it is so potent; however, some of the world’s brightest minds are hard at work studying it—and moving toward figuring out how to stop it. Because understanding a danger is the first step toward protecting oneself from it, I have reviewed the most up-to-date research from reputable sources that is available at this time and have compiled key findings into this two-part series. Although this information may change somewhat over time as we learn more about the Delta variant of COVID-19, here’s what we know right now.

What is a variant? Each virus has its own DNA. When a virus replicates or spreads, errors or mutations occur in this genetic material. In the case of the Delta variant, it produced a stronger form of the coronavirus. Earlier, weaker variants killed more than 600,000 Americans, and Delta is far more dangerous and infectious. Researchers believe that, with more and more Americans becoming infected with Delta, this may set the stage for even stronger variants to appear in the future.

What is the Delta variant? COVID variants are named based on the Greek alphabet. Scientists have identified the Alpha variant, which was discovered in England; Beta, in South Africa; Gamma, in Brazil; and Lambda, in South America. The Delta variant of COVID-19 was first identified in India in December 2020. Since then, Delta has spread to more than 130 countries, including the United States, where it is now the dominant variant.

What is the impact of the Delta variant? Using my home state of South Carolina as an example, we can see how COVID infection rates have experienced a resurgence as the Delta variant has taken over as the dominant strain. Below are the COVID-related hospitalization and death statistics from the SC Department of Health and Environmental Control (SCDHEC) for the 4-week time period of July 16, 2021-August 15, 2021:

  • Number of COVID cases reported: 21,990 (86% were not fully vaccinated)
  • Number of COVID hospitalizations: 1088 (72% were not fully vaccinated)
  • Number of COVID deaths: 384 (78% were not fully vaccinated)

As I noted previously, cases appeared to be declining in June. Indeed, the numbers listed above reflect massive increases from SCDHEC’s statistics for June 2021:

  • Number of COVID cases reported: 5,344 (93% were not fully vaccinated)
  • Number of COVID hospitalizations: 243 (86% were not fully vaccinated)
  • Number of COVID deaths: 39 (90% were not fully vaccinated)

Examining the data for these two time periods highlights how, as the Delta variant has become the dominant type of COVID in South Carolina and the US, COVID cases have gone back on the upswing (as well as the importance of getting vaccinated to prevent death or hospitalization!). Comparing the two 4-week time periods, we can see that reported SC COVID cases and hospitalizations both quadrupled, and there were 10 times more COVID deaths from July 16-August 15 than there were from June 1-30!

Why is the Delta variant moving so quickly? In a recent Yale School of Medicine article by Kathy Katella, epidemiologist Dr. Perry Wilson noted that the Delta variant was spreading 50% faster than Alpha variant, which was 50% more contagious than the original strain of coronavirus. Similarly, an internal CDC report obtained by the New York Times called the Delta variant as contagious as chickenpox! The CDC document, which was created by analyzing numerous studies on COVID, also noted that the Delta variant is more transmissible than the viruses that cause SARS, the 1918 Spanish flu, Ebola, smallpox, common colds, and the seasonal flu.

But why does it spread so quickly and easily? A study comparing those infected in the initial COVID-19 outbreak with those who contracted the Delta variant found that the mutation “grows more rapidly inside people’s respiratory tracts and to much higher levels,” Michaeleen Doucleff of NPR reported. This study found that Delta variant sufferers had 1000 times more copies of the virus in their respiratory tracts than those with the original COVID strain—meaning that those infected with the Delta variant release much more of the virus into the air when they cough, sing, laugh, shout, talk, and breathe…and others around them can inhale this viral material, especially if they’re unmasked. The same study also noted that people carrying the Delta variant become infectious sooner: the original form of the virus takes about 6 days to become detectable within a person, but the Delta variant incubates in just 4 days.

Due to these factors, those who have the Delta variant have the potential to spread it far and wide. In fact, research has shown that the average person infected with the original virus spreads it to one to three people, whereas someone with the Delta variant spreads to five to eight people. From there (unless the newly infected individuals take care not to transmit it further by masking and self-isolating until they are no longer contagious) the variant spreads like wildfire!

Is the Delta variant more dangerous to your health? Compared to those with the original virus, people who contract the Delta variant are more likely to get very sick and require hospitalization, according to studies conducted in Canada and Scotland. In fact, the Scottish study, which was published in The Lancet, suggests that the risk of hospitalization with the Delta variant is double that of the Alpha variant.

Why do vaccinated people seem to be getting sick with COVID now? Although most vaccines drastically reduce your chances of becoming sick, no vaccine is 100% effective. The likelihood differs by vaccine, but there’s always some chance that inoculated people can still get sick, whether it comes to COVID-19 or other illnesses like the flu.

All of the COVID vaccinations that have been approved by the American FDA are highly effective; however, “breakthrough” cases of COVID—which occur when a vaccinated person still contracts the virus—seem to be occurring at a higher rate for the Delta variant than the original strain of COVID. Given that the Delta variant is now the dominant strain, more and more breakthrough cases are popping up (although we cannot know exactly how many because the CDC no longer monitors overall COVID vaccine breakthrough cases, only those resulting in hospitalization and/or death). However, an article in the August 18, 2021 Wall Street Journal drew upon data from 44 state health departments to estimate that there were nearly 200,000 breakthrough cases between January 1, 2021 and early August 2021.

When COVID breakthrough cases occur in vaccinated individuals, they are typically much less likely to get seriously ill, be hospitalized, or die than those who are unvaccinated. The vaccines are about 90% effective in preventing serious illness, i.e., hospitalization or death, as a result of COVID-19 infection, according to current research. This is partially because most vaccinated folks gain immune defenses from their shots that typically destroy the virus before it reaches the lungs, preventing it from causing serious breathing issues. Nationwide, on average, more than 95% of hospitalized COVID patients are unvaccinated. (Read my recent article about COVID vaccines at www.mikedubose.com/blog/should-i-take-the-covid-19-vaccine for more information.)

Although breakthrough cases can end in hospitalization or death, it is rare. As of September 7, 2021, the CDC is aware of about 14,000 breakthrough COVID cases resulting in hospitalization and approximately 2,675 deaths. Unfortunately, one of these rare cases struck close to home. My former neighbor, Dr. Cary Washington, became ill from the coronavirus and died, 30 days after being “fully inoculated.” WIS-TV and USA Today have both reported in detail on Dr. Washington and his story.

Data is also now emerging that suggests that COVID vaccines’ effectiveness decreases over time, which, when coupled with the strength and transmissibility of the Delta variant, could explain the rise in breakthrough cases. Recent reports from Israel, which began inoculating its population in January 2020, suggest that the Pfizer vaccine takes a dip in effectiveness about 6 months after an individual receives their second shot. There is no clear consensus yet amongst scientists, but some researchers who analyzed health statistics collected by the Israeli government estimated that the Pfizer shot was only about 40% percent effective against preventing infection in late June and early July 2021. (Likewise, some Americans began getting COVID vaccinations starting in February and March 2021 and are coming up on six months since their second shot.) A new Israeli study, published at the end of August 2021, suggests that a third COVID shot significantly lowers the risk of infection, even from the Delta variant. Israeli health officials are now offering these “booster shots” to all vaccinated people in the country over the age of 12. In mid-August, the CDC and US Department of Health and Human Services (HHS) announced a plan to provide Americans with free COVID booster shots in fall 2021, so those should be coming soon, starting with high-risk individuals.

Can vaccinated people also spread the Delta variant? Researchers believe that less than 1% of fully vaccinated people contract COVID. However, these breakthrough cases may be hard to recognize because many vaccinated people who get COVID may not even know they have it—they are asymptomatic (have no symptoms) or have symptoms so mild that they think it’s just a cold or allergies. Unfortunately, this may lead them to forgo safety precautions that they would follow if they knew of their infection (such as masking and quarantining), but fully vaccinated individuals who are infected with the Delta variant carry just as much of the virus in their respiratory tracts as unvaccinated individuals. As Apoorva Mandavilli wrote when reporting on the internal CDC document obtained by the New York Times, “Detailed analysis of the spread of cases showed that people infected with Delta carry enormous amounts of virus in their nose and throat, regardless of vaccination status.”

I have already had COVID-19. Can I be reinfected? Studies show that individuals who have previously had COVID can be reinfected with the Delta variant! Even worse, reinfected people are more likely to experience mild or no symptoms—which increases the chance they will unknowingly spread the virus to others. Those who have already had COVID, therefore, should still get vaccinated in order to cut down their likelihood of contracting the virus again. If previously infected individuals get even one vaccine shot after they have recovered, they can significantly increase their antibodies. According to an August 2021 USA article by Adrianna Rodriguez, “Although antibodies from natural infection may provide some protection against the virus, evidence shows nothing protects against COVID-19 better than vaccines.”

Are children safe from the Delta variant? In the early stages of the COVID pandemic, some people claimed that children were immune to the virus. Although it does seem that children were somewhat resistant to the original strain, they appear to be considerably more susceptible to the Delta variant. Children under the age of 12 are not yet eligible to receive COVID vaccinations, and because the Delta variant now causes nearly all US COVID infections, we have seen concerning increases in the number of children infected with COVID in recent weeks.

According to the American Academy of Pediatrics, over 5 million children have tested positive for COVID since the beginning of the pandemic. About 750,000 (or 15%!) of those cases were reported between August 2 and September 5, 2021 alone, and over 250,000 child COVID cases were reported in only one week! Sadly, more children are getting seriously ill and being hospitalized due to the Delta variant as well. CDC data shows that, from August 28, 2021 to September 3, 2021, an average of 367 children aged 0-17 were admitted to US hospitals each day due to COVID. Fortunately, child death rates due to COVID have remained fairly consistent at .01%, but some medical professionals are concerned that these numbers could rise as the Delta variant continues to spread. According to current research, less than 500 children in the US have died thus far. This may seem like positive news, but it’s important to remember that even that “small” number represents entire families that were devastated by their child’s unexpected and tragic passing!

The beginning of the school year has also brought challenges—and the potential for more COVID infections amongst young people. Unfortunately, many South Carolina school districts started the new school year without requiring masks or social distancing in in-person classes, and COVID has spread throughout schools to staff and students as a result. Although it is still early in the school year, some schools and even entire districts have already been forced to temporarily go back to virtual schooling because positive cases required students and employees to quarantine! South Carolina Education Superintendent Molly Spearman, State Epidemiologist Linda Bell, pediatricians, and teachers’ unions have all expressed concerns about the danger of COVID to children if more schools do not take serious precautions to prevent its spread.

If my child contracts a mild or moderate case of COVID, will there be any long-term complications? Many individuals who are infected with COVID-19 recover completely…but some (up to 30%, according to some studies) experience a condition called “long-haul COVID” or “long COVID,” where symptoms can last for months or even years. This can happen to children as well as adults. Research has also suggested that significant numbers of adults and children had lingering heart-related and other issues after their recovery, including headaches, fatigue, and even psychiatric problems. (Read more about the long-term effects of COVID in my earlier articles at www.mikedubose.com/blog/coronavirus and www.mikedubose.com/blog/is-it-safe-to-return-to-churches-gyms-and-restaurants.)

The Bottom Line: COVID-19 is truly a “novel,” or new, virus. This means that we are all learning it about it as we go along, and some of the lessons have been hard ones! The more we research and understand the virus, however, the better we can protect ourselves and others from serious illness and death. I hope this article has helped you to feel more informed. Stay tuned for the second segment of this two-part series, where I will discuss ways to keep your mind and body healthy during this difficult time!

Mike DuBose has been an instructor for USC’s graduate school since 1985, when he began his family of companies, and is the author of The Art of Building a Great Business. Visit his nonprofit website www.mikedubose.com for a free copy of his book and additional published business, travel, and personal articles, as well as health articles written with Surb Guram, MD.