(CNN) — US Surgeon General Dr. Vivek Murthy warned in a new advisory that health misinformation is “a serious threat to public health,” as administration officials grow increasingly concerned about misleading claims about coronavirus vaccines.

“I am urging all Americans to help slow the spread of health misinformation during the COVID-19 pandemic and beyond,” Murthy wrote in a 22-page advisory released Thursday. “Health misinformation is a serious threat to public health. It can cause confusion, sow mistrust, harm people’s health, and undermine public health efforts. Limiting the spread of health misinformation is a moral and civic imperative that will require a whole-of-society effort.”

The stark statement from the surgeon general comes as dangerous falsehoods about Covid-19 vaccines are swirling and as health experts warn of the Delta variant’s increasing spread among unvaccinated Americans.

Nationwide vaccination rates are dropping, while in 46 states, the rates of new Covid cases this past week are at least 10% higher than the rates of new cases the previous week, according to data from Johns Hopkins University.

At Thursday’s White House press briefing, Murthy blamed misinformation for the slowing pace of vaccinations.

“It’s one of several reasons why people are not getting vaccinated, but it’s a very important one, because what we know from polls … is that two-thirds of people who are not vaccinate either believe common myths about the COvid-19 vaccine or think some of those myths might be true,” Murthy said.

Asked whether he believed public figures and companies that are helping spread misinformation should be held accountable, Murthy suggested that everyone, but especially those with large platforms, shares accountability.

“All of us have to ask how we can be more accountable and responsible for the information that we share,” he said, adding that those with larger platforms “bear a greater responsibility to think about that.”

In the memo, Murthy said that misinformation “has also led to harassment of and violence against public health workers, health professionals, airline staff, and other frontline workers tasked with communicating evolving public health measures.”

Murthy noted there is a historical context to his warning, referencing how false beliefs that the measles, mumps and rubella vaccine caused autism caused vaccine levels to drop and the denial that HIV causes AIDS reduced access to treatment in the past. He also highlights how the “rapidly changing information environment” — social media platforms and new publications — has made it easier for misinformation to spread, citing a study that false news stories “were 70 percent more likely to be shared on social media than true stories.”

The advisory lays out recommendations for families, health professionals, researchers, educators, media, funders, government and technology platforms, and urges individuals to take responsibility to limit the spread of misinformation.

“Before posting or sharing an item on social media, for example, we can take a moment to verify whether the information is accurate and whether the original source is trustworthy,” it reads. “If we’re not sure, we can choose not to share.”

CNN previously reported the White House is preparing to push back more aggressively on vaccine disinformation as vaccinations have dropped. This advisory is not part of that effort but will be used by officials as they call attention to the dangers of vaccine misinformation, according to an official.

The divide between vaccinated and unvaccinated has begun to break along political lines, with Democratic-leaning areas ahead of Republican ones in vaccination rates. Officials attribute part of the reason for the discrepancies to messages repeated in conservative media that question why people need the vaccine and that President Joe Biden’s attempts to get the country vaccinated amount to government overreach.

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