Differing strains of the coronavirus continue to appear around the world and a new COVID-19 variant, the so-called "Delta" variant, has health experts concerned.
The variant, otherwise known as B.1617.2, was first detected in India and is highly transmissible, and may be associated with more severe disease and a higher risk of hospitalization, experts say.
The variant now accounts for nearly 10 percent of new cases in the United States, the Centers for Disease Control and Prevention said Tuesday. The change in classification "is based on mounting evidence that the Delta variant spreads more easily and causes more severe cases when compared to other variants, including B.1.1.7 (Alpha)," the CDC said in a statement to NBC News.
The variant has ravaged India and is rapidly spreading in the United Kingdom, becoming the dominant strain there and accounting for 60% of all new cases, CNBC reports.
Dr. Anthony Fauci warned Tuesday that "we cannot let that happen in the United States," noting the the Delta variant currently accounts for more than 6% of cases scientists have been able to sequence in the U.S. In some states, however, the Delta variant accounts for over 18% of sampled coronavirus cases, according to the CDC.
Fauci, along with other top health experts, are urging Americans to get vaccinated to prevent the proliferation of the variant in the U.S. But just how effective are vaccines against the variant, and how do symptoms differ from COVID-19?
What is the COVID-19 "Delta" variant?
First documented in India in October 2020, the strain was named the "Delta variant" by the WHO after the global health agency implemented a new naming system based on letters of the Greek alphabet. The World Health Organization reported the Delta variant has been detected in more than 60 countries.
Global health agencies have classified this specific strain as a "variant of concern" because its highly transmissible and could potentially lead to increased hospitalizations, more strain on health care resources and ultimately, more deaths, according to the Centers for Disease Control and Prevention.
What are the symptoms of the COVID-19 Delta variant?
Symptoms of the variant are similar to that of the original virus, just more severe. It could also be less responsive to treatments and vaccines, according to The Associated Press.
The symptoms include stomach pain, loss of appetite, vomiting, nausea, joint pain and hearing loss.
Dr. Bhakti Hansoti, an associate professor of emergency medicine and international health at Johns Hopkins University, told USA TODAY that doctors have seen an increased likelihood of hearing loss, severe stomach pains and nausea in patients infected with the new variant. In most cases, patients are more likely to be hospitalized, require oxygen treatments and endure other complications.
Doctors in India say the prevalence of digestive issues and other symptoms as a result of the Delta variant appear to be greater than those brought on by the original strain of COVID-19. However, more clinical research needs to be done to confirm the link.
“We need more scientific research to analyze if these newer clinical presentations are linked to B.1.617 or not,” Abdul Ghafur, an infectious disease physician at the Apollo Hospital in Chennai, told Bloomberg.
Are vaccines effective against the new COVID-19 Delta variant?
Scientists think so but are still waiting for definitive answers.
A recent study from Public Health England showed that two doses of the Pfizer-BioNTech vaccine were 88% effective against symptomatic disease from the B.1.617.2 variant two weeks after the second shot. However, the study also showed that one dose of the Pfizer vaccine proved only 33% effective.
The AstraZeneca vaccine, which has not been approved for use in the U.S., was also effective against symptomatic disease for the Delta variant. The study found that two doses of the AstraZeneca vaccine were 60% effective against symptomatic disease.
Marco Cavaleri, head of vaccines at the European Medicines Agency, said last month the data appeared “rather reassuring” that vaccines made by Johnson & Johnson and Moderna would protect against the Delta variant.
In the areas of the U.K. worst hit by the Delta variant, Britain’s health secretary Matt Hancock said most people hospitalized had “chosen not to have the jab.”
Generally speaking, however, the Pfizer, Moderna and Johnson & Johnson vaccines have been shown to be highly effective against COVID-19.
Booster shots will likely be needed to contain spread of the virus as variants continue to propagate throughout the world and the U.S.