(CNN) An outbreak of a vaping-related illness in the United States has sickened hundreds and may be linked to the deaths of seven people , and an epidemic of youth vaping there has been called a "public health crisis."

President Donald Trump's administration moved to ban e-cigarette flavors and there are warnings to avoid vaping altogether, and

But in the UK, there doesn't appear to be an outbreak of vaping-related sickness. Neither has vaping's popularity soared among young people who never smoked. Rather, e-cigarettes have been embraced mostly as a way for adults to quit combustible cigarettes. Indeed, health authorities in the UK stand by their support for e-cigarettes as a cessation tool.

"If you don't smoke, don't vape," said John Newton, director of health improvement at Public Health England. "But if you smoke there is no situation where it would be better for your health to continue smoking rather than switching completely to vaping.

"PHE's advice remains that e-cigarettes are a fraction of the risk of smoking, and using one makes it much more likely you'll quit successfully than relying on willpower alone."

What's different? Regulation, especially on advertising and promotion, and the levels of nicotine in vaping products.

"In the UK the culture is that this is a replacement and not an initiation product," said Bonnie Halpern-Felsher, a professor of pediatrics in Stanford Medicine's Division of Adolescent Medicine.

The great vape debate

In a review last year, Public Health England found that vaping is 95% less harmful than smoking conventional cigarettes and was helping 20,000 people quit a year. The agency was concerned that more than half of smokers "falsely believed that vaping is as harmful as smoking."

"There is much public misunderstand about nicotine," the body said, with "less than 10% of adults understand that most of the harms to health from smoking are not caused by nicotine."

It also said that concern about e-cigarette use as a gateway to smoking among young people wasn't supported by evidence in the UK, where regular vaping among young people who've never smoked is less than 1%

"Similar choice of flavors exist in the US and UK and yet we do not have the same levels of youth vaping here. Our much lower rates are due to our much stricter advertising regulations and possibly our lower nicotine cap," a spokesperson for Public Health England said Thursday.

Halpern-Felsher noted those differences, too.

"In the UK, first of all, they are not allowing advertisements in the same way and so you don't get advertisements to young people," Halpern-Felsher said. Outdoor advertisements on buses, for example, are allowed, but "e-cigarette companies just don't have the presence on social media and in the TV or radio."

In the United States, more than a quarter of high school students were current e-cigarette users in 2019, according to preliminary numbers from the National Youth Tobacco Survey revealed last week.

The EU's Tobacco Products Directive, which took effect in 2016, lays down rules on the manufacture, presentation and sale of e-cigarettes in member countries. This includes restrictions on labeling, packaging and advertising. An EU report on the health and environmental risks of e-cigarettes is due by the end of 2020.

more potent. EU regulations also restrict e-cigarette liquids used in vaping devices to a nicotine strength of no more than 20mg/ml but in the US, some Juulpods contain 59 mg/ml , making themmore potent.

A 5% nicotine Juulpod contains "the amount of nicotine found in two packs of cigarettes -- one and a half to two packs," Halpern-Felsher said . "Whereas the UK would not allow that."

Juul says a 5% strength Juulpod is designed to replace one pack of cigarettes in terms of the number of puffs and the nicotine strength. The company says its studies "have consistently shown that use of JUUL products with 5% nicotine strength results in a nicotine uptake similar to, but lower in concentration than, a cigarette," and that Juul's "nicotine experience" was developed to help adult smokers transition from combustible cigarettes.

Regulatory differences

That's not to say there's no concern over the safety of e-cigarettes in the UK.

One 2018 study found that, among young people in Great Britain, those who had ever smoked were more likely to start vaping -- and those who had ever used an e-cigarette, even if they weren't smokers, were more likely to start smoking.

Public Health England said that vaping "is not completely without risks" and stressed that vapers should use "UK-regulated e-liquids and never risk vaping home-made or illicit e-liquids or adding substances, any of which could be harmful."

And the UK Medicines and Healthcare products Regulatory Agency said 62 reports of adverse reactions linked to e-cigarettes had been reported by the public and health professionals between May 20, 2016 and September 6, 2019.

It's a far cry from the United States, where illness and addiction have hoisted vaping into headlines.

The CDC says there are 380 confirmed and probable cases of lung disease associated with e-cigarette product use, or vaping. It's not clear what's causing the illnesses, although some of the patients vaped THC, the psychoactive ingredient in marijuana. The US Food and Drug Administration also said in August it was investigating 127 reports of seizures that might be linked to vaping.

The Trump administration's moves to ban e-cigarette flavors "will serve as a powerful tool that the FDA can use to combat the troubling trend of youth e-cigarette use. We must act swiftly against flavored e-cigarette products that are especially attractive to children," Acting FDA Commissioner Dr. Ned Sharpless said last week. "The tremendous progress we've made in reducing youth tobacco use in the US is jeopardized by this onslaught of e-cigarette use.

"Nobody wants to see children becoming addicted to nicotine, and we will continue to use the full scope of our regulatory authority thoughtfully and thoroughly to tackle this mounting public health crisis."

Some in the UK were critical of the Trump administration's plan.

Dan Marchant, the owner and founder of Vape Club in the United Kingdom and founding member of the UK Vaping Industry Association, warns that banning products could "create a black market" -- an argument that has been made by US vaping advocates , as well.

"We know prohibition doesn't work. Regulation does work," Marchant said. "From the UK perspective, we have a very highly regulated market ... The diseases that are being reported don't really correlate with the ingredients in professionally manufactured e-liquids."

Professor Linda Bauld, professor of public health at University of Edinburgh, said that it would be a mistake for the United States to ban flavored e-cigarettes.

"It is true that a rising number of American teenagers have tried or recently used flavored vapes and this has caused alarm. But by removing all these products from the market, the proposed US policy forgets that the flavors are an important part of the appeal to adult smokers trying to quit smoking," she said.

"In Europe, flavored e-cigarettes have contributed to recent declines in adult smoking and well-conducted randomized controlled trials show that these products do help people quit."

Views on vaping around the world

Some 35 million people around the world are believed to be using e-cigarettes or newer heat-not-burn products, according to data and research company Euromonitor.

They are popular among smokers in many places trying to kick the habit, as they satisfy the urge for nicotine while removing exposure to the tar and toxins of burned tobacco, but many worry they're creating new addictions to nicotine, particularly among young people.

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Dr. Vinayak Prasad, head of the World Health Organization tobacco control program , told CNN in an email on Thursday that WHO "was actively monitoring developments in the US and other countries and will update governments in due course," adding that its member states hadn't reported similar lung illnesses to those seen in the United States.

The organization also hasn't thrown its weight behind the use of e-cigarettes as a way to quit.

"The scientific evidence on e-cigarettes as cessation aids is inconclusive and there is a lack of clarity as to whether these products have any role to play in smoking cessation," the global health body said in a July report. "There are also real concerns about the risk they pose to non-smokers who start to use them, especially young people."