There are multiple coronavirus variants circulating around the globe since COVID-19 first emerged as a threat some 18 months ago. The latest one to garner attention is the delta variant, first detected December 2020 in India. Considered more transmissible than other lineages, delta has spread to at least 62 countries, including the United States, and is now the U.K.'s most dominant strain, responsible for 91 percent of new cases.
Designated by the World Health Organization (WHO) as a global "variant of concern" (VOC), delta is being blamed for a second deadly wave of infections in India, a country that on June 9, reached a world record daily high of more than 6,000 deaths in one day.
"It potentially could be one of the more difficult viruses to date," says Dr. Paul Goepfert, a professor of medicine at the University of Alabama at Birmingham and an expert in vaccine design. "We'll just have to see if it's more problematic."
Advertisement
What Is the Delta Variant?
Coronavirus disease, or COVID-19, is caused by a single species of virus known as SARS-CoV-2. When the original virus, also called "normal," or "wild type," replicates, or copies itself, the sequence of its molecules, called nucleotides, sometimes changes a little from the original virus. These changes are called mutations. Most of the time, these variations don't work or make the virus weaker.
But sometimes they can make the virus stronger, more contagious or more resistant to the immune system. These variations of the wild-type virus, or variants, catch the eye of health officials in the global SARS-CoV-2 laboratory network at the WHO's Virus Evolution Working Group. The group is tasked with quickly detecting variants and assessing their possible impact.
Delta is the fourth global variant of concern WHO has identified since the pandemic began. The three others — alpha, beta and gamma — were first identified in the United Kingdom, South Africa and Brazil, respectively. Scientifically, the delta variant is known as B.1.617.2.
The delta variant has become a VOC due to some mutations in the spike protein, says Mehul Suthar, assistant professor of pediatrics at Emory Vaccine Center and Yerkes National Primate Research Center.
If you recall the images of coronavirus from the CDC, the spike proteins are those red protrusions rising up from the main "ball," or lipid bilayer membrane, of the virus. Spike proteins are responsible for penetrating host cells and causing infection. At least four mutations in the delta variant have been associated with faster spread and/or higher infectivity based on previous variants with similar mutations.
Advertisement
What Are the Symptoms of the Delta Variant?
With most coronaviruses, you can expect the some of the same symptoms:
- Fever or chills
- Cough
- Shortness of breath or difficulty breathing
- Fatigue
- Muscle or body aches
- Headache
- New loss of taste or smell
- Sore throat
- Congestion or runny nose
- Nausea or vomiting
- Diarrhea
Delta infections carry similar symptoms. But doctors treating patients in India told Bloomberg News that COVID patients they have treated have also reported hearing loss, swelling around the neck and tonsillitis.
Blood clots are a concerning complication of COVID-19. But Dr. Ganesh Manudhane, a cardiologist in Mumbai, India, said he has seen a surprising number and type of blood clots in recent COVID patients across age groups with no past history of abnormal clotting. Several patients have developed micro thrombi, or small blood clots, so severe that some have developed gangrene and required amputations of fingers or a foot. "We suspect it could be because of the new virus variant," he told Bloomberg.
However, it is important to note that these observations are anecdotal and not based on scientific research at this time.
Advertisement
Could Delta Become Widespread in the U.S.?
The vaccines are proving their worth in countries where shots are more readily available. Ironically, India is home to the world's largest vaccine manufacturer, but is struggling with a major internal shortage of shots. Only 3.35 percent of the population is fully vaccinated against the virus and, as a result, the country is engulfed in a deadly second wave.
Comparatively, just over half (51.66 percent) of the U.S. population is fully vaccinated, and both new cases of COVID and related deaths have been trending downward.
The delta variant accounts for about 6 percent of new COVID cases in the U.S., the Biden administration said June 8, 2021. But health officials say the percentage is likely higher as the country's system for tracking coronavirus variants is lacking.
The dominant strain here is currently the alpha, known by the scientific name B.1.1.7. But Dr. Anthony Fauci, chief medical advisor to the president, warned that delta — which scientists say appears to be 40 percent to 60 percent more transmissible than alpha — could soon become the dominant strain in the U.S. as well.
And one age group where cases are climbing the most is among the 12- to 20-year-olds, Fauci says. One reason may be because this age group is among the last to get vaccinated, Goepfert adds.
"Initially we try to vaccinate our older population and rightfully so and we're seeing the benefits of that in decreased hospitalizations," he says. "But now we're seeing [infections] that are mainly in younger people and we're focusing on the fact it's not a completely benign infection in younger people. They're not as at-risk but they have problems too with this and some of them get really, really sick."
Advertisement
Do COVID Vaccines Protect Against the Delta Variant?
It's too early to say for sure whether approved COVID vaccines protect against the delta variant, Goepfert says, but early data is promising.
According to a preprint study conducted in the U.K., one dose of the two-dose Pfizer vaccine provided about 33 percent protection against the delta variant. Two doses were 88 percent effective.
No data has been published, to date, on the efficacy of the two other vaccines approved by the Food and Drug Administration (FDA) for emergency use in the U.S. — the two-shot Moderna vaccine or the one-shot Johnson & Johnson vaccine — against the delta variant. But Dr. Fauci told the Washington Post that he believes Moderna's vaccine would be as effective as Pfizer's shot.
Both Moderna and Pfizer's COVID vaccines are made using mRNA technology. Previous studies have shown that a full double-dose of Pfizer's or Moderna's vaccine provides 95 percent and 94 percent protection against the original virus, respectively. Johnson & Johnson's one-shot vaccine, which uses a modified adenovirus, was found 72 percent effective against the wild-type virus.
"We really got lucky especially with the mRNA vaccines that we achieved such a high protective efficacy. This is something that was not expected when these vaccines were first generated," Suthar says. "I think 50 percent is great but when you start hitting 90 percent, that's even better."
"These vaccines are remarkable," Goepfert agrees. "Even in older adults, it works really, really well which is unusual for most any vaccine that we have. So that's just remarkable."
Advertisement
Comments
Post a Comment