Share on Pinterest
The delta variant was first identified in India. DIBYANGSHU SARKAR/AFP via Getty Images
  • The delta variant is spreading globally.
  • Experts think that this version is more infectious than earlier variants of the virus.
  • While some vaccinated people have developed COVID-19 from the delta variant, they appear to have less severe symptoms than unvaccinated people.

The delta variant of the novel coronavirus is quickly spreading globally, leading to lockdowns in some countries that previously had few reported COVID-19 cases. This variant first identified in India is said to be even more contagious than the British variant (now known as alpha).

“At this point, the delta variant comprises roughly 25 percent of new infections [in the United States],” said Dr. David Hirschwerk, an attending infectious diseases specialist at Northwell Health in Manhasset, N.Y. “In some regions of the country, the percentage is higher, and over the coming weeks, it will very likely be the dominant strain in the U.S.”

So what exactly is the delta variant of COVID-19 and what do we need to know about it right now? We reached out to experts to help shed some light on the subject.

The delta variant is a version of the coronavirus that has been found in more than 80 countries since it first was detected in India. The delta variant is now potentially responsible for over 90 percent of all new cases in the United Kingdom, according to data from Public Health England.

In the United States, the variant is believed to be responsible for roughly 25 percent of all new cases, but that percentage is quickly growing.

In the United States, the delta variant is affecting mostly people who are unvaccinated or only partially vaccinated.

According to the Centers for Disease Control and Prevention (CDC), nearly 78 percent of the population older than 65 years old is vaccinated. Since many older people and those with underlying conditions are already vaccinated, the virus is spreading predominantly among those who are not — patients in their 20s, 30s, and 40s who are either unvaccinated or partially vaccinated.

“It is extraordinarily contagious,” said Dr. William Schaffner, professor of preventive medicine and health policy, Division of Infectious Diseases, Vanderbilt University School of Medicine in Tennessee. “Given that it is so very contagious, remember, the virus’ only job is to infect someone else so it can keep reproducing. Here in Nashville, essentially 90 percent of people hospitalized today are unvaccinated or incompletely vaccinated.”

If you’ve heard of the delta variant, chances are you’ve likely heard of the delta plus variant. It is the latest version of the coronavirus, announced by Indian health officials in late June. As of June 24, there were about 40 cases of the delta plus infections, according to NPR. Indian authorities are on alert given the contagiousness of the original delta variant.

The mutations don’t seem to be great enough for there to be any significant distinction between the delta variant and the delta plus.

“Many mutations have no notable effects on the virus or only modest effects,” said Schaffner. “So it would appear that this delta plus variant is interesting to the virologists, but with no substantial immediate public health implications because it does not appear more contagious or more severe than delta itself.”

Do fully vaccinated people have to worry about the delta and delta plus variants? News out of Israel may suggest yes. Still, it is important to note it’s not confirmed whether these “breakthrough” patients are fully or partially vaccinated.

According to the Wall Street Journal, about half of new COVID-19 cases were vaccinated people in Israel. Preliminary findings have found that the delta variant accounts for about 90 percent of new COVID-19 cases in Israel.

According to a Public Health England study published in May, a single dose of either AstraZeneca (not currently approved in the United States) or Pfizer’s vaccines reduced the risk of developing symptoms due to the delta variant by 33 percent. After two doses, the Pfizer/BioNTech vaccine was 88 percent effective against symptomatic disease from the delta variant.

“The tragedy is that the vaccines work. Essentially every hospitalization, death, or admission to the intensive care unit is preventable if people would get vaccinated. And we have plenty of it,” said Schaffner. “If we look at the age distribution among people now becoming infected and winding up in the hospital, they are much younger than they were initially. That is because so many older people are vaccinated. The unvaccinated part of our population is concentrated in the young adult age group.”

What makes the delta and delta plus variants even more concerning, aside from their increased transmission rates, is that they may put patients at risk for developing other long-term health problems, though the data on that is still preliminary.

“The question is not only is it more contagious, but might it produce more severe diseases? Are you more likely to have a severe infection? The data are less certain, but there are some suggestions that that is the case,” said Schaffner.

Overwhelmingly, the hard data shows that getting vaccinated is still the most reliable way to avoid acquiring or transmitting any strain of COVID-19, the delta variants included.

“The current vaccines are effective at providing protection against the delta variant,” added Hirschwerk. “There will continue to be some breakthrough infections in people who are vaccinated, regardless of the strain. However, it remains the case that in vaccinated individuals who have breakthrough infections, the symptoms are very mild or the patients are asymptomatic and only detected by screening.”

He added that of all individuals admitted to hospitals in the past month with COVID-19, less than 1 percent were fully vaccinated.