Amid a cluster of good news, such as ample vaccinations for American adults by the end of May, a plunge in coronavirus cases and planned reopenings, health experts such as the Centers for Disease Control and Prevention remain concerned and have pleaded with the public to stay vigilant.

On one hand, both virus-contraction and COVID-19 fatality rates in the US have continued to drop in the past two weeks, signaling that the pandemic that has claimed more than 510,000 American lives has weakened.

Over the last week, roughly 65,422 new cases were recorded daily, compared with the peak of nearly 250,000 daily cases in January, according to data by Johns Hopkins University.

Adding to the optimism, President Joe Biden told Americans on Tuesday that "this country will have enough vaccine supply, I'll say it again, for every adult in America by the end of May", at the White House.

Joining the jubilant chorus on the same day were Texas Governor Greg Abbott and Mississippi Governor Tate Reeves: Both states rescinded mask mandates and allowed businesses of any type to fully open — Mississippi this Wednesday and Texas next week.

In San Francisco, Mayor London Breed gave the green light to restaurants for indoor dining to restart on Wednesday at 25 percent capacity and a maximum of 100 people.

On the other hand, CDC experts warned the nation that a highly contagious variant, first identified in the UK and known as B.1.1.7, "looms ready to hijack" progress against the virus.

The US is at a "critical nexus", said Rochelle Walensky, the CDC director, on Wednesday at a White House daily briefing, adding that the number of daily new infections is still above the rate last summer. In 14 states, coronavirus cases grew by more than 5 percent, up from only two states a week ago.

According to January CDC research, the B.1.1.7 strain would become predominant in the US by mid- to late March, could reverse the current downward trajectory in infections, and ultimately postpone an overall recovery. "Now more than ever, we must do all we can to stop the spread of the virus," Walensky said.

Bombarded by conflicting messages and directives, the general public is baffled — whether or not to wear a mask, to return to work, to send children back to school, to vaccinate — all leading to moments of indecision.

Some call moves by state governments "blunt and radical", the Texas practice in particular.

"There were over 7,200 new cases on March 2. Seven-day average is above 7,000. How could Governor Abbott ignore the harsh reality but push for reopening?" said Jackie Zhou, a Texas mom of two young children. "This is an act with utter disregard for human life."

San Francisco resident David Tsu, 72, said the "time is not ripe yet" for the city to reopen indoor dining. Given the city is still averaging 67 new coronavirus cases a day, "Mayor Breed needs to think twice, especially (because) the variants also were reported in the Bay Area," he said. "We can't afford another round of shutdown and stay-in-place."

For those parents who have school-age children, to choose between on-site teaching and distance learning is a headache. Worse, public figures in the government and public education system are sending contradictory messages.

For example, Berkeley Federation of Teachers President Matt Meyer was caught on camera recently dropping his daughter off for in-person learning at a private school. However, Meyer, as the head of a Northern California teachers union, is the mastermind behind the "Gold Standard" campaign, which advocates for continuing closure of local public schools until all staff members are vaccinated.

"He's been saying it is unsafe for ‘your kid' to be back at school, all the while dropping his kid off at private school," a parent vented on Twitter.

In his defense, Meyer issued a statement on Monday saying, "There are major differences in running a small preschool and a 10,000-student public school district in terms of size, facilities, public health guidance and services that legally have to be provided. "We all want a safe return to school."

In California, students in kindergarten through second grade are scheduled to return to class by the end of March.

The question remains, how safe is safe enough? Listen to President Biden, he warned: "It's not over yet. Stay vigilant."