More than two years into the coronavirus pandemic, Anthony Fauci, the nation's top infectious diseases expert, said he understands people are exhausted, but is urging those who are not up to date on the vaccines to get the shots - this time, as the latest omicron subvariant, BA.5, has become the dominant strain in the United States.

Fauci told Los Angeles radio station KNX News earlier this week that although people who are unvaccinated and those with underlying conditions are at the greatest risk of complications from COVID-19, others are not exempt.

"If they don't get vaccinated or they don't get boosted, they're going to get into trouble," he said.

BA.5, which has been called "the worst version of the virus," accounts for more than 85% of cases of COVID-19, with more than 41% of U.S. counties experiencing a high COVID-19 community level, according to the most recent data from the Centers for Disease Control and Prevention. Some health experts have expressed concern that not enough people are vaccinated, particularly as the nation has fallen away from restrictions and mandates, such as masking, to help control the spread of the disease.

In fact, the majority of the U.S. population is not up to date on the vaccines - defined by the CDC as having completed the primary series and all booster doses recommended for that individual. CDC data shows that 67% of the U.S. population is fully vaccinated but only 48% has received the first booster shot. Only 32% of people 50 and older - who are eligible for a second booster - have received that extra dose.

Fauci said it's important to get as many people vaccinated and boosted as possible so the virus does not have "ample opportunity to freely circulate." When the virus is given that opportunity, he said, it can continue to mutate.

"It is about you as an individual, but it's also about the communal responsibility to get this outbreak under control," he told the radio station.

That said, it is not uncommon for people who are vaccinated to become infected. President Joe Biden, who is vaccinated and double-boosted, recently tested positive for the virus - and then got a rebound infection - though he experienced "very mild symptoms."

Health experts, including Fauci, have repeatedly pointed out that research shows the shots still protect against severe complications, including hospitalization and death. As of July 27, there were more than 126,000 new cases reported daily, with 6,340 hospitalizations and 364 deaths, according to CDC data.

"Right now we have boosters that are very effective in diminishing any aspect of the infection," Fauci told KNX News. "A virus like BA.5, which is the most prevalent circulating virus, is so transmissible that it often breaks through the protection of vaccine. But the vaccines and the boosters still do a very good job at preventing you from progressing to severe disease."

Additionally, a booster designed to target the omicron variant is likely to be rolled out in the fall with the intent to broaden immunity.

"You don't want COVID to dominate the lives of people in this country or throughout the world, but you don't want to, by wishing it's behind us and it's in the rearview mirror, not do things that would be prudent," Fauci said.