Even as the nation reopens and many people shed their face masks, COVID-19 continues to threaten, this time as a new variant more easily spread with different and more dangerous symptoms.

The Delta variant – widespread in China – is already in the United States, accounting for about 10 percent of current COVID-19 infections, according to Dr. Ulysses Wu, Hartford HealthCare’s System Director of Infection Disease and Chief Epidemiologist.

“The variant is similar to the original strain but appears to be more infectious, which could lead to more cases and, therefore, complications if there are more cases,” Dr. Wu said.

Chinese officials have reported that patients with the Delta variant, labeled a “variant of concern” by the World Health Organization, tend to become sicker faster, with about 12 percent of patients becoming severely ill within four days of the onset of symptoms. The majority also exhibit higher concentrations of the virus in their bodies than noted with previous strains, and the virus levels decline much more slowly.

Complicating the matter: The existing COVID-19 vaccine and medications used to help treat patients severely ill with previous variants may have reduced effect against the Delta variant, Dr. Wu said.

“The vaccine should protect people to some extent but not to the extent that it should,” he said, although he added that “the vaccine still fulfills its primary purpose, which is to reduce the amount of hospitalizations and deaths associated with the virus. Data from the (United Kingdom) shows that even though cases may be increasing, deaths have actually stayed the same as the U.K. has a high vaccination rate.”

He said he expects more COVID-19 deaths attributed to the newest variant, especially among people who remain unvaccinated. He urged those who have not yet been vaccinated to consider taking the protective step. Other preventive measures that can help include continuing to practice physical distancing and hand washing guidelines.

“People should also still be wearing face masks to protect themselves when they are indoors with other people of unknown vaccine status,” Dr. Wu said, adding that masks are not necessary when people are outdoors unless they are in large crowds.