Teen drug use is on the decline, with one notable exception: marijuana. Nearly 23 percent of high school seniors report using marijuana in the past month, according to new data from an annual survey funded by the NIH. The survey polls 8th, 10th, and 12th grade students across the country about their drug and alcohol consumption. “Now we have more teenagers smoking marijuana than cigarettes,” said Dr. Nora Volkow, the director of the National Institute on Drug Abuse. “If you ask if they smoke, they think you mean marijuana,” she told me. Other highlights from the report:

• In 1991 — the first year the survey collected data on cigarette smoking — nearly 11 percent of high school seniors smoked at least half a pack a day. In 2015, just 1.8 percent of high school seniors did.
• Heroin use remained relatively stable, with 0.3 percent of high school seniors reporting they’ve injected heroin in the past year.
• Just under 5 percent of high school seniors report having used opioid pain relievers for non-medical reasons, down from a peak rate of 9.4 percent in 2004.
• The rate of non-medical use of the ADHD drug Adderall — which 6 percent of high school seniors reported using in the past year — has remained fairly stable.

The FTC has settled charges against the makers of the Instant Blood Pressure app, which was touted as being as accurate as a traditional blood pressure cuff. The app asked users to put their right index finger over the rear camera lens and hold the base of the phone over their heart. But blood pressure readings from the app, created by AuraLabs, were much less accurate than a traditional blood pressure cuff. That could pose a threat to patients, the agency said. The FTC also alleged that the company's owner gave his product a five-star review in the app store without identifying his affiliation. The company was fined nearly $600,000, but the fine was suspended because of the company’s inability to pay.

Four major medical groups are also turning their attention to health apps, teaming up to tackle issues of safety, quality, and efficacy. The newly launched nonprofit collaboration — dubbed Xcertia — consists of the American Medical Association, the American Heart Association, the Healthcare Information and Management Systems Society, and DHX group. First up on their to-do list: Lay out the kind of clinical evidence that should guide design of mobile health apps and collect doctor and patient reviews of the hundreds of thousands of apps on the market.

Despite what the commercials of runners hitting the pavement may show, there isn’t any evidence that shock-absorbing shoe insoles actually prevent injuries or stress fractures according to a new review paper. Researchers culled data from 11 clinical trials on foot orthotics and another seven studies of shock-absorbing insoles. Insoles are designed to soften impact, while foot orthotics are intended to even out pressure on the foot. Shock-absorbing insoles didn’t reduce the risk of any type of injury, including tendon or muscle problems, knee pain, or back troubles. The silver lining for your sore feet? Foot orthotics were associated with a 41 percent lower risk of stress fracture in the legs or feet.

I keep track of negative trial findings that affect human health from head to toe in this newsletter. If you see one, send it my way at newsletter@statnews.com.

At one point in time, SARS, Ebola, and Zika each existed as unknown viruses lurking in nature. Each came to threaten global health, leaving scientists to scramble to identify the microbe and develop a plan of attack to stop its spread. And in each case, health officials concluded those countermeasures weren’t ready in time to stop the outbreak. "Always too late," said Jonna Mazet, a scientist keen to break the bugs’ winning streak. "We need to think about something different." Now, Mazet and other researchers are throwing their weight behind a lofty endeavor known as the Global Virome project. They’re working to catalogue those unknown viruses lurking in nature to find threats to human health before they find us. STAT’s Helen Branswell has the story here. 

The proportion of the at-risk population in sub-saharan africa with access to a mosquito net. (WHO)

The WHO reports this morning that 43 percent of people in sub-Saharan Africa still aren’t protected by two main methods of malaria control, insect nets and insecticide use indoors. But there has been other progress. In sub-Saharan Africa — home to 90 percent of malaria cases and 92 percent of malaria deaths last year —  pregnant women and children are receiving better care, the agency reports. In 2015, half of kids who showed up at a public health facility with a fever received a malaria test, compared to 29 percent in 2010. And the proportion of women getting a preventive treatment known as ITPp increased fivefold in the past five years — 31 percent of pregnant women in 20 high-risk African countries now receive the treatment, which reduces both maternal and infant complications from malaria.

The proportion of infants born with neonatal abstinence syndrome is on the rise in rural regions of America. Newborns whose mothers used opioids during pregnancy can experience withdrawal-like symptoms — seizures, trouble feeding, and excessive crying — after birth. A new analysis published in JAMA Pediatrics finds that the proportion of infants diagnosed with NAS who were from rural counties jumped to 21 percent in 2013, up from 13 percent a decade prior. It’s possible that the increase could be due, in part, to greater awareness in those hospitals about opioid-related conditions such as NAS. But the study’s authors say there’s still a geographic disparity when it comes to opioid prevention and treatment efforts, and that it's impacting infants as well as adults.

Good news from HHS — a national push to make health care safer seems to be making a dent in hospital-acquired infections. Hospital-acquired infections can crop up in patients who are being treated for another condition, and in some cases, can be life-threatening. Obamacare included incentives to help health care facilities cut down on hospital-acquired infections. In the years since those kicked in, the number of infections has fallen. Last year, 87,000 fewer patients died due to hospital-acquired infections. Between 2010 and 2014, that falling infection rate translated to $20 billion in health care cost savings.