When Pooja Mehta’s younger brother, Raj, died by suicide at age 19 in March 2020, she felt “blindsided”. Raj’s last text message was to his college lab partner about how to divide homework questions. “You don’t say you’re going to take questions one through 15 if you’re planning to be dead one hour later,” said Mehta, 29, a mental health and suicide prevention advocate in Arlington, Virginia.

She had been trained in Mental Health First Aid — a nationwide program that teaches how to identify, understand, and respond to signs of mental illness — yet she said her brother showed no signs of trouble. Mehta said some people blamed her for Raj’s death because the two were living together during the COVID-19 pandemic while Raj was attending classes online. Others said her training should have helped her recognise he was struggling.

But Mehta said: “We act like we know everything there is to know about suicide prevention. We’ve done a really good job at developing solutions for a part of the problem, but we really don’t know enough.” Raj’s death came in the midst of decades of unsuccessful attempts to tamp down suicide rates across the United States.

During the past two decades, federal officials have launched three national suicide prevention strategies, including one announced in April. The first strategy, announced in 2001, focused on addressing risk factors for suicide and leaned on a few common interventions. The next strategy called for developi.