It appears that the mysterious vaping-related illness sweeping the United States has started to slow down. On Friday, the Centers for Disease Control and Prevention announced that the casualty rate for the as-yet-unexplained health condition is “leveling off or even declining.”

The most recent victim count — calculated last Tuesday — stands at 1,604 individuals who have shown signs of the condition. 125 cases were diagnosed over the last week, and 34 people have died from the illness.

“It’s serious and potentially fatal, but it is preventable,” said CDC principal deputy director Anne Schuchat to reporters. “There could be more than one cause.”

She said that the dip in cases might be due to the measures that authorities have taken to regulate the products. There has also been a wave of high profile arrests made of illegal vaporizing product manufacturers, and busts of brands found to be making dangerous vape products.

Schuchat also presented a hypothesis that e-cigarette use led teenagers to use “risky products” that cause the lung condition. Some authorities have blamed the spate of lung injuries on additives in vaping products, like the vitamin E acetate that is sometimes used as a thickening agent. The official also raised her concern over how winter-time flus and other respiratory illnesses could affect the people who have been stricken with the vape-related sickness.

Earlier this month, a Mayo Clinic surgical pathologist released a report based on findings from examining 17 victims. The investigation found that the lung condition showed similarities with chemical burns, as when individuals inhale mustard gas.

Vape-Related Illness Now Has a Name

Officials have started calling the lung condition EVALI, which stands for “e-cigarette or vaping product use associated lung injury.” Concern over the illness has led many states and city governments to put temporary bans on e-cigarette and vaping products. In Massachusetts, Governor Charlie Baker’s ban on all vapes has faced legal challenges, but was recently ruled as acceptable by a state judge.

In Michigan, Governor Gretchen Whitmer has vowed to fight the state’s Supreme Court decision to block her ban of flavored e-cigs. The prohibition had been in effect for two weeks, after a month-long delay in implementation. Whitmer likened the urgency of the ban to the concern over her state’s water quality. “After seeing how the Flint water crisis was mishandled, it’s more important than ever that we listen to our public health officials when they make recommendations to protect our citizens,” she said.

Those are far from the only challenges to new vaping restrictions. In Utah, retailers sued the state’s Department of Health over creating the ban without public comment, claiming that the prohibition would severely harm their businesses.

Earlier this month, a group of governors from Northeastern states came together to discuss tactics for standardizing the regulation of vaping. One potential measure for the region was banning flavored e-cigarette products across the board, in hopes of slowing down the popularity of vaping among teenagers.