WASHINGTON - Key indicators of COVID-19 transmission in the United States continue to fall, but health experts warn the public not to let down guard as the country sees uptick in coronavirus variants infections.

Weekly new cases have fallen from 1.7 million at the national peak in early January to fewer than 600,000 this week, and cases have declined in every state, according to The COVID Tracking project.

Cases have been falling sharply for five weeks, hospitalizations for four, and deaths for two, according to the tracking project.

The current 7-day average increase of cases is 77,385, a 68.9 percent decline from the highest 7-day average of 249,048 on Jan 11, data from the U.S. Centers for Disease Control and Prevention (CDC) show.

The numbers of new hospital admissions of patients with confirmed COVID-19 decreased from the national peak of 18,006 on Jan 5 to 6,841 admissions on Feb. 16, a 62 percent decrease, according to the CDC.

The average number of daily admissions fell by 21.8 percent compared to the previous week.

The 7-day average number of new COVID-19 deaths also decreased by 9 percent to 2,708 per day compared to the previous 7-day period, CDC data show.

The drop of cases, hospitalizations and deaths are encouraging, said Stanley Perlman, professor of microbiology and immunology at the University of Iowa.

"It may mean that we are over the holiday bump," he told Xinhua in an interview on Saturday.

"It is too early to know if this is a turning point because new, more contagious variants are circulating in the United States," Perlman noted.

A total of 1,549 infection cases of coronavirus variants had been reported in the United States as of Thursday, according to the CDC.

The vast majority of these cases, 1,523, were caused by the variant known as B.1.1.7, which was originally detected in Britain.

There were 21 cases of a new strain initially discovered in South Africa, called B.1.351, and five cases of the P.1 strain first discovered in Brazil.

Modeling data suggest that B.1.1.7 could become the predominant variant in the United States in March.

"We hope that the vaccine rollout will outweigh the variants spread," Perlman told Xinhua.