Enormous death tolls could occur if the U.S. allowed the coronavirus to spread unchecked in an attempt to try to achieve so-called herd immunity, Dr. Anthony Fauci, the top U.S. infectious diseases expert, warned in a live Instagram session last Thursday.

File photo: CFP

Herd immunity, also known as community immunity, occurs when a sufficient portion of a population is immune to a specific disease (usually through vaccination and/or prior illness), so that it can make the spread from person to person unlikely.

"If everyone contracted it, even with the relatively high percentage of people without symptoms ... a lot of people are going to die," he said.

Fauci noted that with the number of people with diabetes and obesity in the U.S., "the death toll would be enormous and totally unacceptable" if everyone got infected.

The World Health Organization has also warned that relying on herd immunity to combat COVID-19 is a "dangerous" idea.

An ensemble forecast released by the U.S. Centers for Disease Control and Prevention on August 13 projects nearly 189,000 coronavirus deaths in the U.S. by September 5.

According to Johns Hopkins University, the U.S. has seen over 5.4 million infections and more than 170,000 deaths as of Sunday – both numbers are the highest in the world.