Youths on HIV meds may episodically develop a significant risk of transmitting the virus. This is according to data that researchers analyzed about a group of 240 13- to 25-year-olds receiving HIV treatment at a Philadelphia clinic between 2002 and 2015. They categorized the youths as at high risk for transmitting the virus if at a single clinic visit they had a viral load greater than 1,500 and were diagnosed with gonorrhea, chlamydia or syphilis. (Sexually transmitted infections, or STIs, boost transmission risk when the viral load is detectable.) Twenty-one percent had a viral load above 1,500; 8 percent had a high viral load and an STI but not at the same time; and 17 percent had a considerable transmission risk, with a high viral load and STI diagnosis at the same clinic visit.