WASHINGTON >> A week of public health reversals from the White House and the Centers for Disease Control and Prevention has left Americans with pandemic whiplash, sowing confusion about coronavirus vaccines and mask-wearing as the delta variant upends what people thought they knew about how to stay safe.

Vaccines remain effective and highly protective against hospitalization and death, even among those infected with the extremely infectious delta variant. Mask-wearing prevents transmission of the virus to those most at risk.

But the crisis President Joe Biden once thought he had under control is changing shape faster than the country can adapt. An evolving virus, new scientific discoveries, deep ideological divides and 18 months of ever-changing pandemic messaging have left Americans skeptical of public health advice. So although the White House had promised a “summer of joy,” the nation is instead caught in a summer of confusion.

“While we desperately want to be done with this pandemic, COVID-19 is clearly not done with us, and so our battle must last a little longer,” Dr. Rochelle P. Walensky, the director of the CDC, told reporters today. “This is hard. This is heavy. But we are in this together.”

Today was another day that underscored the crosscurrents for the nation’s leaders as their efforts at a disciplined public health campaign collided yet again with the chaotic nature of the pandemic. Instead of a consistent message, the result was another dizzying jumble of news stories and divergent announcements.

In Louisiana, a state with one of the lowest vaccination rates, Gov. John Bel Edwards reinstated an indoor mask mandate, as did health officials in San Francisco and six other Bay Area counties. But in New York City, Mayor Bill de Blasio declined to do so, even though such a move would have been in line with CDC guidelines.

The virus continued to scramble traditional politics. In left-leaning Chicago, city officials announced that more than 385,000 people had attended the four-day Lollapalooza music festival — and Mayor Lori Lightfoot defended it. In Washington, Sen. Lindsey Graham, R-S.C., a longtime supporter of former President Donald Trump, announced that he had tested positive for the coronavirus, but said his symptoms have been mild, which he attributed to having received the vaccine.

“I feel like I have a sinus infection,” Graham wrote on Twitter. “Without vaccination I am certain I would not feel as well as I do now. My symptoms would be far worse.”

Nationally, caseloads continued to climb. The country reported a daily average of nearly 80,000 new infections on Sunday, up from about 12,000 in early July, according to a New York Times database. A spate of scary news stories about unvaccinated people dying from COVID-19 appears to have accomplished what Biden could not: The nation finally reached the White House’s target, initially set for July 4, of having 70% of American adults at least partially vaccinated.

Some experts say the CDC is to blame for some of the confusion. After saying in May that vaccinated people could go maskless both indoors and outdoors, the agency did an about-face last week, once again recommending indoor masking for everyone — vaccinated or not — in places where the virus is spreading rapidly.

Only days later did a leaked document deliver the grim reasoning: Delta is as contagious as chickenpox and spreading even among the fully vaccinated, which puts unvaccinated people at risk and poses the threat of yet another viral mutation that could evade vaccines.

“The delta variant is different from prior strains,” Walensky said. “I understand this is all frustrating news, and I share this frustration.”

A senior administration official, who spoke on the condition of anonymity to discuss the administration’s thinking, conceded on Monday that many Americans remained perplexed after the flurry of sometimes difficult and seemingly contradictory information.

Another administration official said Biden would address the nation later this week — the second time in less than a week — to reiterate and clarify his main takeaway points: The vaccines are safe and effective. The reason even vaccinated people have to mask up again is that so many people are unvaccinated. So go get your shots and tell your friends and neighbors to do the same.

“The thing that hasn’t changed is the need to get vaccinated; the thing that hasn’t changed is that masks do work and they protect you,” said Dr. Carlos del Rio, an infectious disease specialist at Emory University who lectures on crisis communications.

But del Rio said the CDC made a misstep in May when it told vaccinated Americans they did not need to wear masks — not because the science behind the recommendation was wrong, but because the move led everyone to doff their masks and prompted states, localities and retail businesses to abandon their mask requirements, which enabled the delta variant to flourish.

“That was scientifically correct from a virology standpoint,” del Rio said of the earlier recommendation. “It was wrong from a behavioral science standpoint.”

Across the country, the questions are piling up again: Can I eat inside at a restaurant or bar? What about a sporting event? Should kids be wearing masks when they go to school in September? Will a vaccine for children be available by then and will it be required? What — exactly — are people supposed to be scared of? And what should they do about it?

There is no single answer. The risk is different for different people, depending on whether they are vaccinated and the level of virus in their community. At the same time, the pandemic is fast-moving and ever-changing, which is part of the CDC’s challenge.

“They are in a bit of a no-win situation — this is very challenging to message on,” said Jen Kates, a senior vice president of the Kaiser Family Foundation. “What’s happening is this is real-time public health messaging in a pandemic around data that is just emerging. That is just the reality, and that doesn’t necessarily provide comfort or always the kind of answers that people understand.”

This article originally appeared in The New York Times.

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