A new and increasingly dangerous variant of the SARS-CoV-2 virus is rapidly sweeping across the globe. This new variant appears to spread faster, cause more severe disease and is more likely to result in hospitalization.

Also, younger people appear to be more susceptible to the new strain, known as the Delta variant, according to the Centers for Disease Control and Prevention (CDC).

But the good news is that the existing vaccines now available to everyone over the age of 12 have proven to be highly effective in preventing the Delta variant as well as other versions of COVID-19.

"We know that vaccines work," said Dr. Margaret Ryan, medical director of the Defense Health Agency's Immunization Healthcare Division.

Currently, there are three vaccines authorized for use by the Food and Drug Administration for COVID-19: The Pfizer and Moderna mRNA vaccines require two doses, and J&J/Janssen is a one-dose vaccine.

The Delta variant is spreading quickly and will likely soon become the dominant strain within the United States.

It's a wake-up call for those people who think that they don't need to get a vaccine because they've successfully avoided the COVID-19 disease so far. It may be very difficult to escape the new Delta variant in the coming months without getting the shot, doctors say.

The Delta variant currently accounts for 20.6 percent of sequenced cases in the U.S., and that number is expected to multiply, especially in regions and among populations with low COVID-19 vaccination rates.

The number of sequenced cases of the Delta variant has roughly doubled every two weeks, Dr. Anthony Fauci, chief medical advisor to President Joe Biden, told a June 22 White House media briefing. Fauci is director of the National Institute of Allergy and Infectious Disease at the National Institutes of Health.

The mRNA vaccines made by Pfizer and Moderna have been described as having at least 88 percent efficacy against the Delta variant of SARS-CoV-2, Ryan said.

"But we should not focus too hard on efficacy numbers," she suggested. "All available COVID-19 vaccines have shown strong real-world effectiveness at preventing severe disease by all COVID-19 variants. The most important message is that vaccination saves lives."

Vaccination is also important to prevent new, possibly worse, variants of the virus from appearing, Ryan said. "Every person who gets infected with SARS-CoV-2 allows the virus to replicate, or copy itself, up to one billion times. Every time the virus copies itself, there is a chance for a new variant to appear. We prevent variants from appearing by preventing human infections. We prevent human infections by vaccination," she said.

Because of the Delta variant, “Everyone in the U.S. who is at least 12 years old should be fully vaccinated with a COVID-19 vaccine as soon as possible," Ryan said.

More than half of the U.S. population has received at least one dose of a COVID-19 vaccine; and 150.4 million, or 45.3 percent are fully vaccinated. For those over the age of 65, 87.3 percent have had at least one dose; 77.2 percent are fully vaccinated.